BIDIRECTIONAL METAL SHEET SYSTEM FOR TOWED MARINE CABLE ARRANGEMENT

Abstract

A sheet metal system is used with a towed marine cable assembly to provide downward, upward, or lateral lift to the assembly. The sheet metal system can be coupled with the cable and configured to deflect the submerged payload to a target position. The sheet system may include a group of sheet sections, each with a leading edge that collectively defines an angle of attack, and a group of through cables that support the group of sheet sections within the sheet system. A subset of through cables from the through cable group is arranged across the leading halves of the sheet section group.This subset of through cables can be selectively tensioned and manipulated to define a tensioned through cable from the subset as offset from a chord defined between the leading and trailing edges of any of the blade sections. The blade system can thus induce one or more angles of attack for the group of blade sections, based on a rotational constraint defined by the tensioned through cable of the through cables.

Description

This application claims the benefit of U.S. Provisional Application No. 62 / 955,851 filed December 31, 2019, which is incorporated herein by reference in its entirety and to which priority is claimed. Field of Invention The described embodiments relate generally to towed marine cable assemblies. More specifically, the present embodiments relate to the hydrodynamic orientation control of sheets in the marine cable assembly or arrangement. Background of the Invention In towed marine seismic exploration, a hydrophone array is typically towed behind a marine vessel near the sea surface. The hydrophones are mounted on multiple sensor cables, commonly referred to as transmission cables or streamers. The transmission cables serve as platforms or supports for the hydrophones, which are distributed along each transmission cable in the array. A set of seismic sources, also towed near the sea surface, are put into operation to periodically emit acoustic energy. The acoustic energy of interest MA / IZ / ZUZZ / U0 / 40Z propagates downward through seawater (or other water column), penetrates the ocean floor, is reflected from submarine strata and other underlying structures, and returns upward through the water column to the hydrophone array. The reflected seismic energy (or acoustic wave energy) arrives at receiver points on the towed hydrophone array. The array includes many of these receiver points, distributed along each streamer, with sensors configured to generate data records that characterize the upward-moving acoustic waves (or seismic waves) received from subsurface structures beneath the seafloor at each of the receiver points. The hydrophone data recordings are subsequently processed to generate seismic images of the underlying structure. In the field of underwater seismic exploration, there has recently been a demand from seismic equipment operators to conduct their surveys with the seismic equipment submerged below the depths at which most seismic surveys have been conducted in the past. These new, deeper operational targets can now be well below the depth referenced to the surface by the equipment (i.e., the vessel and paravanes) used for towing and lateral extension. MA / E / ZUZZ / U0z40Z seismic sensors. Typical sheet- or foil-shaped marine depressors for maintaining gear at a substantially constant submerged depth tend to be quite small with very poor aspect ratios, resulting in low lift. Aspect ratio is defined as the spread of the depressor divided by the length of its rope line. Depressors with high aspect ratios generate large downward lift forces for minimal drag (such that lift-to-drag ratios as high as 10:1 or more are possible), while depressors with aspect ratios as low as 1 or 2 (i.e., where the spread and rope are roughly the same scale) will typically have lift-to-drag ratios as low as 2:1 or even lower.Conventional depressors often also provide payload bays that can be used to contain additional ballast to supplement the downforce generated by the depressor. The problem with using deadweight to generate downforce is that it does not increase with towing speed; it provides a constant downforce regardless of the speed at which the depressor moves through the water. This is often a disadvantage for applications where a range of operating speeds is expected, with the requirement that the towed equipment maintain a stable depth over that speed range. Consequently, there is no easy, economical, or ideal way to submerge and operate seismic equipment, such as towed streamers, at the desired shallower depths. The information included in this background of the invention section, including references cited herein and any description or discussion thereof, is included for technical reference purposes only and should not be construed as subject matter by which the scope of the invention as defined in the claims is to be limited. Brief Description of the Invention Embodiments of the present invention relate to angle of attack control for submerged sheets or foils secured to a towed marine cable assembly or array. The foil sections may be coupled to one another by a group of through-wires. A subset of the group of through-wires is disposed across front halves of the foil sections. One or more actuators may generally manipulate the subset of through-wires to induce a first angle of attack, a second angle of attack, and / or maintain the foils at a substantially neutral angle of attack. As described in greater detail herein, this may include having three through-wires (e.g., a subset of through-wires) disposed in front halves. MA / IZ / ZUZZ / U0 / 40Z of substantially symmetrical foil sections and a fourth disposed in rear halves of the foil sections. Selection of one taut through-wire from the three through-wires can define a rotational restraint above, below, and / or in line with a foil chord to induce the respective angle of attack. In some cases, selective tensioning can occur in this manner while at least a portion of the arrangement is submerged in a marine environment, allowing for on-the-fly adjustments to the foil system during operation. While several embodiments are disclosed, an exemplary embodiment of a towed marine cable assembly is disclosed. The towed marine cable assembly includes a cable configured to be towed by a vessel and transport a submerged payload through a marine environment. The towed marine cable assembly further includes a foil system coupled to the cable and configured to deflect the submerged payload toward a target position. The foil system includes a group of foil sections, each of which has a leading edge that collectively defines an angle of attack. The foil system further includes a group of through cables that support the group of foil sections within the foil system. A subset of through cables of the group of through cables is disposed across front halves of the group of foil sections.The subset of through-wires in the group of through-wires can be selectively tensioned. The subset of through-wires in the group of through-wires can be manipulated to define a taut through-wire of the subset of through-wires as offset from a chord defined between the leading edge and the trailing edge of any of the sheet sections. In another embodiment, the towed marine cable assembly may further include an actuator operatively coupled to the through-cable subassembly and configured to alter the tension in one or more through-cable subassembly of the through-cable subassembly. Additionally or alternatively, the actuator may be a first actuator. In this regard, the towed marine cable assembly may further include a second actuator operatively coupled to the through-cable subassembly and configured to manipulate the tensioned through-cable into a position that rotationally restrains the front halves relative to the rear halves of the group of sheet sections. In another embodiment, the feed-through lead subassembly may include a group of leading edge feed-through leads, each of which extends through the front halves of the group of sheet sections and along the leading edge. The feed-through lead subassembly may further include a trailing edge feed-through lead disposed across the front halves of the group of sheet sections and along the leading edge. MA / E / ZUZZ / U0z40Z of rear halves of the group of sheet sections and along the rear edge. A first leading edge through-wire of the group of leading edge through-wires and the trailing edge through-wire may also be arranged substantially along the chord. In another embodiment, a second leading edge through-wire can be arranged above the chord. Furthermore, a third leading edge through-wire can be arranged below the chord. In this regard, in a first configuration, the tensioned through-wire is the second leading edge through-wire. Furthermore, in a second configuration, the tensioned through-wire is the third leading edge through-wire. In another embodiment, each sheet section of the group of sheet sections may be substantially symmetrical along the chord. The group of sheet sections may exhibit a substantially neutral angle of attack, for example, such as when the tensioned through-wire is a cable disposed along the sheet chord line and the second and third through-wires are both in a relaxed state. Alternatively, a non-zero angle of attack may be obtained by transferring tension from the through-wire disposed along the sheet chord line to the through-wire disposed above the chord line (to induce a negative angle of attack) or to the through-wire below the chord line (to induce a positive angle of attack).In this regard, when the tensioned through-wire is displaced from the chord, the tensioned through-wire may rotationally restrain the front halves relative to the rear halves of the sheet section group to define the angle of attack as a positive or negative angle of attack. In another embodiment, the sheet system may be a first modular sheet system. The towed marine cable assembly may further include a second modular sheet system, as described herein. The first and second modular sheet systems may be connected to one another within the towed marine cable assembly. In some cases, the group of through cables of each of the first and second modular sheet systems converge toward a connection point disposed substantially between the first and second modular sheet systems. In another embodiment, the cable may be an upper cable. The towed marine cable assembly may further include a lower cable. The second modular sheet system may be connected to the lower cable. The upper cable and the lower cable may cooperate to form a mouth of a fishing net. The first modular sheet system and the second modular sheet system may be configured to increase the separation distance between the upper cable and the lower cable at the mouth of the trawl. In some cases, the towed marine cable assembly may further include a port cable and a starboard cable that further form the mouth of the fishing net. In this regard, the towed marine cable assembly may further include a third modular sheet system, as described herein, attached to the port cable. In addition, the towed marine cable assembly may also include a fourth modular sheet system, as described herein, attached to the starboard cable. The third modular sheet system and the fourth modular sheet system may be configured to laterally space the port cable and the starboard cable. In another embodiment, the cable may be a component of a seismic receiver array. In this regard, in some cases, the submerged payload may include seismic sources. The seismic sources can be configured to emit energy into the marine environment. In another embodiment, the cable may be a spreader cable. The towed marine cable assembly may further include transmission cables configured to be towed behind the spreader cable. The submerged payload may include seismic receivers carried by the seismic cables. The angle of attack can be configured to maintain the seismic receivers at a desired depth. In another embodiment, the cable may be a side cable of the towed marine cable assembly under tension. The side cable may include an end portion located along an edge of the towed marine cable assembly. The sheet system may be coupled to the side cable adjacent to the end portion. In some cases, the towed marine cable assembly may further include a branch line connected to the end portion of the side cable. The sheet system may be connected to the branch line opposite the side cable. In another embodiment, a foil system is disclosed for deflecting a cable in a towed marine cable assembly. The foil system includes a foil defining a foil shape having a leading edge and a trailing edge. The foil system further includes a first through-wire extending through the foil along the leading edge. The foil system further includes a second through-wire extending through the foil along the trailing edge. The foil system further includes a first actuator configured to tension the first through-wire. The foil system further includes a second actuator configured to move the tensioned first through-wire from an unselected configuration to a selected configuration. When in the unselected configuration, the tensioned first through-wire cooperates with the second through-wire to maintain the foil at a substantially neutral belay angle.When in the selected configuration, the first tensioned through wire cooperates with the second through wire to maintain the foil at a positive or negative angle of attack. In another embodiment, the sheet may be substantially symmetrical and define a chord extending between the leading and trailing edges. The first tensioned through-wire may be arranged offset from the chord in the selected configuration. The second actuator may be coupled to the sheet and the first tensioned through-wire. The second actuator may be configured to move the first tensioned through-wire from a arrangement substantially along the chord in the unselected configuration to the offset from the chord arrangement in the selected configuration. In another embodiment, the first through-wire may be a first leading edge through-wire of a group of leading edge through-wires extending through a front half of the sheet and along the leading edge. The second actuator may be configured to define one of the group of leading edge through-wires as the first tensioned through-wire. In some cases, the second actuator may include a thumbwheel. Each of the leading edge through-wire cables may be attached to the thumbwheel at circumferentially spaced positions. One position MA / E / ZUZZ / U0z40Z The rotating selector wheel can determine which of the leading edge lead-through cables is the first tensioned lead-through cable. The rotation position of the selector wheel can be adjusted while the foil system is submerged in a marine environment. In another embodiment, the front half of the sheet includes a first conduit, a second conduit, and a third conduit. Each of the first conduit, the second conduit, and the third conduit may be configured to receive a respective leading edge through-wire of the group of leading edge through-wires. The sheet may further define a rear half having a fourth conduit configured to receive the second through-wire. Each of the first conduit, the second conduit, the third conduit, and the fourth conduit may extend the full width of the sheet and be disposed substantially parallel to one another. In another embodiment, the first feedthrough cable and the second feedthrough cable may converge to connection points adjacent to opposite ends of the sheet. In some cases, each of the connection points may be configured to couple a pair of feedthrough cables from another sheet system of the towed marine cable assembly to the first and second feedthrough cables. In another embodiment, a method is described for positioning a sheet system on a towed marine cable assembly. The method includes launching an array or assembly into a marine environment. The array may include a cable configured to carry a submerged payload and a foil system coupled to the cable. The foil system may include a group of foil sections defining front and rear halves and connected to each other by a group of through-cables extending therethrough. The method further includes tensioning the first of one or more through-cables of the group of through-cables to define a first rotational restraint of the front halves relative to the rear halves, thereby inducing a first angle of attack. The method optionally further includes tensioning a second of one or more through-cables of the group of through-cables to define a second rotational restraint of the front halves relative to the rear halves, thereby inducing a second angle of attack.A tensioned through-wire of the through-wire group during any of the tensioning operations is displaced from a chord defined between a leading edge and a trailing edge of any of the sheet sections. In another embodiment, the method may further include acquiring submerged positional data associated with the foil system. The method may further include determining a tuning parameter for the foil system by comparing the submerged positional data to an operational target. In some cases, the operation of inducing the first angle of attack or the operation of inducing the second angle of attack may be based on the tuning parameter. In another embodiment, the foil system may further include a dynamic actuator configured to cause any of the tensioning operations while the array is submerged in the marine environment using the adjustment parameter. In another embodiment, one of the first or second angles of attack may be a substantially neutral angle of attack. Each of the group of sheet sections may include a substantially symmetrical sheet. In another embodiment, the group of through-leads may include a group of leading edge through-leads. Each of the group of through-leads may be spaced apart from one another and extend through the first halves of the group of sheet sections along leading edges of the group of sheet sections. In some cases, one of the tensioning operations may define a first leading edge through-lead of the group of leading edge through-leads as the taut through-lead of the group of leading edge through-leads. In this regard, another of the tensioning operations may define a second leading edge through-lead of the group of leading edge through-leads as the taut through-lead of the group of cables. MA / IZ / ZUZZ / U0 / 40Z leading edge through-holes. In another embodiment, the method may further include tensioning a third of one or more lead wires, wherein the third leading edge lead wire is disposed substantially along the string. The array may be a seismic array, one or more components of a fishing net, or other suitable marine system. Accordingly, the seismic array may include seismic sources and seismic receivers that cooperate with each other to produce geological data. In this regard, the methods described herein may be used to induce the first or second angle of attack for components associated with one or both of the seismic sources or seismic receivers, as appropriate for a given application. This brief description of the invention is provided to present a selection of concepts in a simplified form that are described later in the Detailed Description. This brief description of the invention is not intended to identify key features or essential characteristics of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities and advantages of the present invention as defined in the claims is provided in the following written description of various embodiments and implementations and is illustrated in the drawings. MA / IZ / ZUZZ / U0 / 40Z adj unts. Brief Description of the Drawings The description will be easily understood by means of the following detailed description together with the accompanying drawings, in which similar reference numerals designate similar structural elements. Figure 1A represents a top plan view of a schematic illustration of a first example of a towed marine cable assembly. Figure IB represents a rear elevation view of a schematic illustration of the towed marine cable assembly of Figure 1A. Figure 2 represents an enlarged partial rear elevation view of a schematic illustration of one embodiment of the towed marine cable assembly of Figure 1A. Figure 3 shows an enlarged partial rear elevation view of a schematic illustration of the port side of a towed seismic array with a sheet depressor system provided in the branch line and connected to the port paraban flange. Figure 4 shows a schematic illustration of a cable adjustment mechanism for a foil system. Figure 5A represents a schematic illustration of one embodiment of a sheet system of the present invention. MA / IZ / ZUZZ / U0 / 40Z description . Figure 5B represents a schematic illustration of another embodiment of a sheet system of the present disclosure. Figure 6 represents a schematic illustration of another embodiment of a sheet system of the present disclosure. Figure 7A represents an embodiment of an enlarged view of the sheet system having an actuator in a first configuration. Figure 7B depicts an embodiment of an enlarged view of the sheet system having an actuator in a second configuration. Figure 7C depicts an embodiment of an enlarged view of the sheet system having an actuator in a third configuration. Figure 8 represents a schematic illustration of another embodiment of a sheet system of the present disclosure. Figure 9 depicts a sample asymmetric sheet for use with one or more sheet systems of the present disclosure. Figure 10 represents a schematic illustration of another embodiment of a sheet system of the present disclosure. Figure 11 represents a flow diagram for a method of positioning a sheet system in an array. MA / IZ / ZUZZ / U0 / 40Z sailor. Figure 12 represents another embodiment of a towed marine cable assembly. The use of hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements, for example, when shown in cross-section, and also to facilitate the legibility of the figures. Accordingly, neither the presence nor the absence of hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property of any element illustrated in the accompanying figures. Furthermore, it should be understood that the proportions and dimensions (whether relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations and positional relationships presented between them, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale and are not intended to indicate any preference or requirement for any illustrated embodiment to the exclusion of the embodiments described with reference thereto. Detailed Description The following description includes examples of systems, methods, and apparatus that incorporate various elements of the present disclosure. However, it should be understood that the provided description may be practiced in a variety of ways besides those described herein. The present disclosure provides systems, devices, and techniques related to controlling the orientation of one or more sheet systems of a towed marine cable assembly. Such sheet systems may be used to control the movements and / or maintain a position of various instruments, devices, assemblies, etc., of the towed marine cable assembly. For example, a sheet system may include a group of sheet sections that cooperate to define a sheet shape having a leading edge and a trailing edge. The group of sheet sections may be coupled to instruments of the array. When towed, the group of sheet sections may generate lift or lift (e.g., including lateral lift, upward lift, downward lift, etc.), due in part to an orientation or angle of attack of the sheet shape.In turn, this lift can be used to correspondingly move ropes, cables, and instruments attached to the foil system. The foil sections that define the foil shape can be coupled to each other by a through cable and / or other mechanism that allows the foil sections to move relative to each other in a dynamic marine environment. It may be desirable to manipulate the angle of attack defined by the foil group, for example, to adjust the lift generated by the system in response to marine, operational, and / or other conditions or circumstances. The sheet system of the present disclosure may allow the group of sheet sections to be arranged in a variety of orientations. Broadly, a group of through-wires may be used to support a group of sheets or sheet sections within the system. The through-wires may be specifically arranged to define rotational restraints to induce a target angle of attack for the sheet sections. For example, a generally trailing edge through-wire may extend through the rear half of each of the sheet sections, and one or more through-wires may extend through the front half of each of the sheet sections. Each of the through-wires (e.g., a subset of the group of through-wires) may be selectively tensioned and / or manipulated to control the angle of attack of the sheet. As an illustration, the subset of feedthrough cables can be tensioned and moved from a first selected configuration to a second selected configuration. In each selected configuration, one of the feedthrough cables can be tensioned to MA / IZ / ZUZZ / U0 / 40Z define a rotational restraint of the front half of the blade relative to the trailing half of the blade. The rotational restraint may be adapted to induce a given angle of attack based on a configuration or position of the selected and tensioned through-wire relative to the trailing edge through-wire. For example, the trailing edge through-wire may be disposed along the chord of the blade defined between the leading edge and the trailing edge of the blade. When the selected and tensioned through-wire of the subset of wires in the front half of the blade is disposed along the chord, the blade may exhibit a substantially neutral angle of attack, similar to the case of substantially symmetrical blade shapes. When the selected and tensioned through-wire of the subset is disposed below or above the chord, the blade may exhibit a non-zero angle of attack. In one embodiment, the subset of feedthrough wires may include three feedthrough wires, a first leading edge feedthrough wire, a second leading edge feedthrough wire, and a third leading edge feedthrough wire, which may generally be disposed in a front half of the sheet or group of sheet sections. For a substantially symmetrical sheet cross-section, the first leading edge feedthrough wire may be positioned generally along the chord of the sheet, the second leading edge feedthrough wire may be positioned generally along the chord of the sheet, and the third leading edge feedthrough wire may be positioned generally along the chord of the sheet. MA / IZ / ZUZZ / U0 / 40Z can generally be placed above the chord, and the third leading edge through-wire can generally be placed below the chord. Furthermore, as stated above, the trailing edge through-wire can be placed along the chord and across the rear half of the sheet. In this regard, the sheet can be supported within the arrangement by four cables. The sheet system may include one or more actuators to facilitate selective tensioning and manipulation of the subset of through-leads disposed in the front half. For example, the sheet system may include a first actuator coupled to one or more of the subset of through-leads. The first actuator may be configured to induce tension in some or all of the subsets of through-leads. Imposing a tension distribution across the subset of through-leads in the front half of the sheets that is symmetrical with respect to the sheet chord line may cause the sheets to assume a zero or neutral angle of attack. Alternatively, imposing a tension distribution that is asymmetrical with respect to the sheet chord line may cause the sheets to assume an asymmetric (or non-zero) angle of attack.In this way, the tensions of the subset of through wires can be manipulated or selected to define a rotational constraint that obtains a desired angle of attack. MA / IZ / ZUZZ / U0 / 40Z As such, the sheet system may also include dedicated actuators for each through-wire in the front half of the sheet section. In general, a set of three actuators may be configured to manipulate the subset of through-wires to define the rotational restraint of the front half relative to the rear half of the sheet. For example, the set of actuators may be configured to concentrate tension across a selected one of the subset of through-wires, such that the selected through-wire is used to define the rotational restraint of the front half of the sheet relative to the rear half of the sheet.For example, when the first actuator applies tension to the first leading edge through-cable, the orientation of the foil may be defined by the first leading edge through-cable and the trailing edge through-cable, each of which is disposed along the chord, and therefore, the foil may assume a substantially neutral angle of attack. As another example, when the second actuator applies tension to the second leading edge through-cable, the orientation of the foil may be defined by the second leading edge through-cable and the trailing edge through-cable. When the second leading edge through-cable is positioned above the chord, the foil may assume a negative angle of attack, generating lift in a vertically downward or negative direction.As another example, when the third actuator applies tension to the third leading edge through-cable, the foil's orientation can be defined by the third leading edge through-cable and the trailing edge through-cable. When the third leading edge through-cable is positioned below the chord, the foil can assume a positive angle of attack, generating lift in a positive or vertically upward direction. In other configurations, other angles of attack can be generated and / or maintained. It will be appreciated that the embodiments described herein are not limited to a sheet system having four through-cables. For example, the provided disclosure also encompasses sheets that are supported by two through-cables within a towed marine cable assembly. In this arrangement, one or more actuators may operate to define one or more rotational restraints of the front half of the sheet relative to the rear half of the sheet section. As an illustration, the subset of through-cables extending across the front half of the sheet may be a single leading edge through-cable. The single leading edge through-cable may be disposed within the sheet such that the cable may rotate or move relative to the chord of the sheet. For example, the single leading edge through-cable may be disposed in a guide or cam member that facilitates movement of the through-cable within the sheet.In this manner, the second actuator may engage or at least partially define the cam and cause the single leading edge through-wire to be positioned, when tensioned, along, above, and / or below the chord. As stated above, the trailing edge through-wire may be positioned along the chord and across the trailing half of the foil section. In this regard, an actuator may be used to induce or maintain a neutral, positive, and / or negative angle of attack based on the position of the single leading edge through-wire. In other embodiments, other arrangements are possible, including those with three, five, six, or more cables, and thus, the discussion of embodiments having two or four through-wires should not be construed as limiting. Furthermore, asymmetric foils may also be used in certain applications and as described herein. Reference will now be made to the accompanying drawings, which help illustrate various features of the present disclosure. The following description is presented for purposes of illustration and description. Furthermore, the description is not intended to limit the inventive aspects to the forms disclosed herein. Accordingly, variations and modifications consistent with the following teachings and the skill and knowledge of the relevant art are within the scope of the present inventive aspects. One embodiment of a towed three-dimensional marine seismic array 100 is depicted in Figures 1A and 1B. The array 100 may be adapted to use one or more of the foil systems, such as those discussed generally above and described in greater detail below (for example, including the foil system 500 of Figure 5A, below). Referring to Figure 1, the array 100 is towed by a marine vessel 102. Various cables, ropes, or other lines may be attached to the marine vessel 102. For example, an umbilical cable 104 with acoustic signal source generators (e.g., air guns) may be trailed directly behind the marine vessel 102. A pair of tow ropes 106 or cables may extend port and starboard from the stern of the marine vessel 102.A cross cable 108 may extend between and connect to tow cables 106 adjacent to the aft ends of the tow cables 106. A plurality of drive cables 110 may be connected to the cross cable 108 at various locations along the length of the cross cable 108 between the tow cables 106. In some embodiments, the drive cables 110 may be evenly spaced from adjacent drive cables 110 along the cross cable 108. In a typical embodiment, there may be up to 18 drive cables 110 and they may be spaced anywhere between 10 m to 100 m or more apart. Respective tail buoys 111 may be attached to the ends of each of the drive cables 110, which may assist in maintaining the position of the drive cables 110, providing a visual marker for the arrangement and so forth. The cross cable 108 may extend beyond the port-most and starboard-most cables 110 to join the tow ropes 106. These lateral sections of the cross cable 108 may be referred to as drop lines 114. In some embodiments, the drop lines 114 may be separate ropes or cables that connect to and extend between the lateral ends of the cross cable 108 and the tow ropes 106. The paravanes 112 may be further attached to the tow ropes 106 at or adjacent the connection between the tow ropes 106 and the drop lines 114 on each of the port and starboard sides. The paravanes 112 are hydrofoils or winged hydrofoils that move outward in the water in a direction oblique to the direction of travel of the marine vessel 102, thereby providing lateral extension to the cross cable 106 and the drive cables 110 attached thereto. In other configurations, alternative extension devices may be employed to maintain separation of the drive cables 110, including aluminum fins, as described in U.S. Patent No. 10,254,422. A signal cable 116 may extend from the marine vessel 102 on one side of the array 100 to connect to the cross cable 108 and return signals received by the sensors 111 onto the transmission cables 110. On an opposite side of the array 100, a recovery rope 118 may extend from the marine vessel 102 and connect to the cross cable 108 adjacent to the last transmission cable 110. Surface floats 117 may be attached to the cross cable 108 at or adjacent the side ends thereof via a cable with a length corresponding to a desired depth of the transmission cables 110. The surface floats 117 act to ensure that the cross cable 108, and therefore the transmission cables 110, do not become too submerged when the array or assembly 100 is towed. Unfortunately, the port and starboard ends of the cross cable 108 and thus the transmission cables 110 attached to them, may not reach the desired depth below the surface due to the pull of the paravanes 112 on the branch lines 114. The paravanes 112 remain at the surface of the water and thus pull the lateral ends of the cross cable 108 upward as well as laterally outward. MA / IZ / ZUZZ / U0 / 40Z To counteract the effect of the fairings 212 on the cross cable 208, a positioning or depressing device 220 designed to provide downward elevation can be attached to the cross cable 208, the lead line 214, or both, as shown in FIG. 2. The depressor 220 can be composed of a series of laminas pivotally attached to the cross cable 208 or the lead line 214. The set of laminas that form the depressor 220 is herein referred to as the modular lamina depressor. As shown in FIG. 2, the modular lamina depressors 220 can fill the entire length of the lead line 214. Alternatively, the modular lamina depressor 220 can only fill a portion of the lead line 214 and can be located laterally outward closer to the fairings 212 or more inward closer to the transmission or seismic cables 210.As indicated above, the modular foil depressor 220 may also be positioned on the cross cable 208, within the port-most and starboard-most cables 210. The location of the modular foil depressor 220 may be selected based on a number of factors, including the amount of downward lift generated by the modular foil depressor 220; the standoff distance of the drive cables 210; the mass of the array sensors, the drive cables 210, and the cross cable 208; and the lift force generated by the paravanes 212, among other factors. In addition to the depth control discussed, as shown in Figure 3, a modular sheet depressor 320 deployed on the shunt line 314 may also provide lift assistance to the paravanes 312 attached by a flange 313 to the intersection of the tow lines 304 and the shunt line 314. While the modular sheet depressor 320 induces a catenary downward to the shunt line 314, as shown in Figure 3, a first component 362 of the lift force 360 ​​acts downward as discussed above, but a second component 364 of the lift force 360 ​​also acts horizontally (i.e., outward). This horizontal lift assistance of the second component 364 provided by the modular sheet depressor 320 means that the existing standard paravanes 312 will now be able to expand the seismic array further than was previously possible.Alternatively, the configuration including the modular foil depressor 320 on the bypass line 314 can achieve the same span, but with a shorter offset behind the marine vessel towing the arrangement. In another implementation, the same span and offset can be achieved, but a more efficient configuration can be used for the bridle 313 securing the paravanes 312, thereby reducing the marine vessel's fuel consumption. Additionally, a plurality of modular foil depressor sections can be used on the. MA / IZ / ZUZZ / U0 / 40Z shunt lines to obtain depression forces to submerge transmission cable heads to the desired depths for seismic arrays. The modular sheet depressor can provide a number of other features and advantages. The modular sheet depressor can be easily installed on existing waterborne equipment, such as by screwing individual depressor sections into existing branch lines between paravanes and external transmission cable headers. Modular sheet depressors can also be installed on many other existing cables. The modular foil depressor can be deployed over the side of the marine vessel or down the gun duct, then automatically orient itself and generate lift without operator intervention. Handling, deployment, and recovery operations are essentially hands-free, with no special davits, winches, or cranes required. The modular foil depressor is also compact and can be easily and efficiently stowed on the vessel when onboard. In other embodiments, a foil system may be used to generate lift along a lateral direction. This may allow a foil system to steer or position a component of the towed marine cable assembly. For illustrative purposes, a foil system is shown in Figure 4. MA / IZ / ZUZZ / U0 / 40Z schematic illustration of a dynamic fin foil system 420, comprised of a number of adjacent foil sections 430. The dynamic fin foil system 420 may generally extend vertically in a marine environment and generate lift that is used to steer the components of the array. To facilitate the foregoing, the dynamic fin foil system 420 is shown in Figure 4 including a representative trim mechanism 450. The trim mechanism 450 may include various components that may be used to manipulate the fin foil system 420, such as manipulating the orientation of the fin foil system 420 to generate a target lift when towed through the marine environment. In one embodiment, the trim mechanisms may include turnbuckles 452 and sheaves 454, ratchets, winches, cable fairleads, and feed mechanisms that may be mounted on the flotation apparatus 418, for example, between one or more of the control feedthrough cables 438 and a rear anchor point 458 on the rear or aft section of the flotation apparatus 418 (in the direction of the trailing edge of the foil sections 430).In some designs, a single control cable 438 may be used, extending from the front cable anchor 456 down along a section of front cable 436, then passing through a cable return or wrapping or folding around it. MA / IZ / ZUZZ / U0 / 40Z of a cable connector 429 connected to a submerged cable 444 and returns upward along a section of stern cable 434 to the after anchor 458 via pulley 454. Alternatively, separate forward and rear control cables 436, 434 may be provided, for example, individually connected to submerged cable connector 429. A separate forward feed-through cable 436 may extend between a termination point 456 on surface float 418 and a termination point 457 at cable connector 459. A rear feed-through cable 434 may extend through foil sections 430 from a termination point 457 at foil connector 429 to a rear termination point 458 on surface float 418. The adjustment mechanism 450 may be configured to adjust either the forward cable 436 or the rear cable 438; both of which embodiments are encompassed. Another option is to use an adjustment mechanism 450 that provides differential adjustments to the forward and rear cables 436, 434; for example, by shortening one cable and lengthening the other at the same time.In some instances, the forward control cable 436 may be a set of forward control cables, such as including three or more forward feedthrough cables, as shown in the embodiment of Figure 5A. In this regard, it will be appreciated that the fin foil system 420 may be manipulated in a manner similar to that described in the embodiment of Figure 5A. The submerged cable 444 may be provided as a towline for a transmission cable 448 or as an umbilical for a fountain gun arrangement. A control device 459 for the trim mechanisms 450 may be located at the upper or lower end of the foil fin system 420, for example, within the flotation apparatus 418 or connected adjacent to the lower rigging hardware 429. Appropriate control devices 459 include processor, memory components, and software configured to direct the trim mechanisms 450 to selectively vary the length and / or tension in any or all of the through cables 438 to regulate the lift and steering forces generated by the foil fin system 420 by changing the angle of attack along individual foil sections 430.For example, the control device 459 may be configured to control electric motors or similar drive devices to actuate the combination trim mechanism 450, providing automatic steering by adjusting the relative lengths and tensions in the front and rear control cables 436, 434. Other control options include, but are not limited to, hydraulically and pneumatically controlled ram or piston mechanisms, electric winch drives, and motor-driven rack and pinion arrangements. For example, in some instances, control systems and configurations such as those described may be employed. MA / IZ / ZUZZ / U0 / 40Z in U.S. Patent Application Publication No. US20170106946A1 to facilitate tensioning of the cables described with respect to Figure 4. In the context of a seismic survey as described above, several seismic energy source devices and / or sensor nodes may be connected along the length of cables deployed and towed behind the marine vessel. Each cable, or seismic equipment attached to the cables, may have an associated steering device to adjust the position of the cable or seismic devices within the water. In some implementations, it may be very important that towed marine equipment, such as cables with seismic equipment, closely follow a predetermined course (e.g., to accurately map a subsurface formation). Additionally, if multiple cables are deployed behind a marine vessel, it may be important to maintain a constant separation distance between the cables.To meet these needs, steering mechanisms can be connected to each cable and additionally or alternatively to the equipment towed by the cable. The 420 foil fin systems are just one exemplary implementation of a steering mechanism that can be employed to direct and position cables, seismic energy sources, sensor nodes, buoys and floats in the seismic array, etc. Other steering mechanisms exist for MA / IZ / ZUZZ / U0 / 40Z attachment to such sensor array components. These may include paravanes, hydrofoils or hydrofoils, rudders, fins, elevators, and various other devices. The orientations of each of these devices while being towed through the water can be adjusted for steering. Such adjustments can be made by increasing or decreasing the tension on the control cables (i.e., making them tauter or slacker), activating actuators to physically move a steering element, activating motors to drive rotating elements, etc. In each case, the steering mechanisms are controlled by signals with calculated instructions to alter the orientation of the steering mechanisms appropriately to maintain a proper heading for the elements of the seismic array or set within the water.These signals are determined by sophisticated navigation and control systems that work in conjunction with the marine vessel's navigation to ensure that the seismic array elements remain on course and maintain appropriate separation distances between adjacent elements. Figures 5A and 5B depict sample illustrations of embodiments of a sheet system of the present disclosure. In particular, Figures 5A and 5B depict sheet systems in which the feed-through wires can be selectively tensioned and manipulated to define various rotational restraints that can induce an angle of MA / IZ / ZUZZ / U0 / 40Z target attack. As described herein, this may include inducing a positive, negative, and / or neutral angle of attack, as appropriate for a given configuration. In general terms, embodiments herein show that one or more through-wires disposed in the front section of the blade can be tensioned and manipulated to a selected configuration in which the given through-wire can define the rotational restraint. In this regard, when the tensioned and selected through-wire is disposed along the chord, the blade can assume a substantially neutral angle of attack. And further, when the selected through-wire is disposed above and / or below the chord, the blade can assume a substantially negative or positive angle of attack, respectively. It will be appreciated that the blade systems described with respect to Figures 5A and 5B can be used with a towed marine cable assembly. The towed marine cable assembly can be one of many towed marine cable assemblies adapted for particular applications, such as seismic surveys. Therefore, the blade systems can be adapted for use in a variety of marine contexts. In one modality, the towed marine cable assembly can be a seismic assembly and the blade system can be used to influence a direction or position of components of the seismic assembly. This can be beneficial when the position of selective components of the array can be used to determine geological data.To illustrate, the seismic array may include components for a source array or set (e.g., components associated with emitting energy in a marine environment) and a receiver array (e.g., components associated with receiving reflected energy from geophysical structures in response to emitted energy from the sources). The foil systems may be associated with one or both of the source or receiver sets to influence the position of the respective components of each set. In other examples, such as that described in greater detail below with respect to Figure 12, the towed marine cable assembly may include components of a trawl, and the foil system may influence the position of the trawl components. Accordingly, the foil system described herein may be adapted to these and other array applications. Referring to Figure 5A, a sheet system 500 is shown. The sheet system 500 generally may include a sheet section 504 and a group of through cables 550. The group of through cables 550 is configured to support the sheet section 504 (and / or other sheet sections) in a towed marine cable assembly. In addition, as described herein, the group of through cables 550 may be tensioned. MA / IZ / ZUZZ / U0 / 40Z and manipulate to induce one or more angles of attack of the sheet section 504. To facilitate the above, the sheet section 504 may be scaled to accommodate a wide range of lifting requirements while offering very high aspect ratios and avoiding any additional ballast requirements. The sheet section 504 may have a sheet-shaped body 505 having a leading edge 512 and a trailing edge 516. The line connecting the leading edge 512 and the trailing edge 516 that passes through the middle of the thickness of the body 505 is referred to as the chord line of the sheet shape, indicated as chord 510 in dashed lines in Figure 5A. When viewed from a top plan perspective, the sheet section 504 may appear rectangular in shape. The surfaces extending between the leading edge 512 and the trailing edge 516 may be symmetrically cambered to define a substantially symmetrical cross-section of the body 505.In other cases, such as that shown in Figure 9, one surface may be more or less curved than the opposite one and thus define a substantially asymmetrical sheet body. The body 505 may be fabricated from solid cast polyurethane for near-neutral buoyancy and high abrasion resistance and durability. However, the body 505 may still have slightly negative or positive buoyancy, such that the body 505 may influence the equilibrium angle of attack when towed horizontally through the water, especially at low towing speeds. Thus, the downforce obtained by the foil section 504 may be influenced by selecting the composition of the body 505. The foil body may also include internal voids that can be filled with positively or negatively buoyant materials to further influence the equilibrium angle of attack of the foil body when towed through the water in a horizontal orientation. A collection of leading edge tubular conduits or ducts may be defined within body 505 and extend laterally through body 505 adjacent leading edge 512 and open to each of the first and second lateral sides of the sheet. For example, Figure 5A shows a first conduit 520a, a second conduit 520b, and a third conduit 520c. Each of the first conduit 520a, the second conduit 520b, and the third conduit 520c are disposed adjacent leading edge 512 and within and through a front half 506 of body 505. The first conduit 520a, the second conduit 520b, and the third conduit 520c may be sized to receive pass-through cables, strings, or cables (such as standoff strings and / or drop lines) of a seismic array therethrough. Another tubular conduit or duct may be defined within the body 505 forward of the trailing edge 516 and extending laterally in the same parallel to the collection of tubular conduits or ducts that are along the leading edge 512 and open to each of the first and second lateral sides of the sheet body 505. For example, Figure 5A shows a fourth conduit 520d, which may be positioned within the trailing 50 percent of the chord length of the sheet section 504, as if it were within the trailing half 508 of the sheet body 505. The fourth conduit 520d may be similarly sized to receive a pass-through cable, string, or other cable therethrough. Figure 5A also shows the sheet system 500 including the group of through-leads 550, as described above. The group of through-leads 550 may include a subset of through-leads 554 disposed substantially within the front half 506 of the sheet body 505. While many configurations are possible, the subset of through-leads 554 may include a first leading edge through-lead 554a, a second leading edge through-lead 554b, and a third leading edge through-lead 554c. The group of through-leads 550 may also further include a trailing edge through-lead 558 disposed within the trailing half 508 of the body 505. The group of through-leads 550 is shown extending through the sheet section 504 through several conduits defined through the body 505.For example, the first leading edge feed-through cable 554a may be disposed within the first conduit 520a, the second leading edge feed-through cable 554b may be disposed within the second conduit 520b, the third leading edge feed-through cable 554c may be disposed within the third conduit 520c, and the trailing edge feed-through cable 558 may be disposed within the fourth conduit 520d. As shown in Figure 5A, the first conduit 520a and the fourth conduit 520d are disposed substantially along the chord 510. The second conduit 520b is disposed above the chord 510. The third conduit 520c is disposed below the chord 510. It will be appreciated that other arrangements of the conduits are possible and are contemplated within the scope of the present disclosure. As described herein, the feed-through cable subassembly 554 may be selectively tensioned and manipulated to define a rotational restraint of the first half 506 of the body 505 to the second half 508 of the body 505. For example, one or more first actuators (e.g., first actuator 670 of FIG. 6 ) may operate to tension the feed-through cable subassembly 554. This may include inducing an initial baseline of tension in each of the feed-through cable subassemblies 554, thereby allowing the feed-through cable subassembly 554 to be further manipulated to define the various rotational restraints herein. Continuing with the illustration, one or more second actuators (e.g., second actuator 680) may operate to manipulate the subassembly of through-wires 554 such that a given wire of the subassembly is used to define a rotational restraint of the front half 506 relative to the rear half 508. For example, the second actuator may effectively apply tension to the subassembly of through-wires 554 through a particular through-wire of the subassembly 554, thereby defining the rotational restraint based upon the positional disposition of the particular through-wire relative to the chord 510. To illustrate, in one configuration, tension may be applied to the first leading edge through-wire 554a of the subassembly 554, and as such, the position of the sheet section 504 may be defined by the cooperative effect of the first leading edge through-wire 554a and the trailing edge through-wire 558 on the sheet section. 504.Since both the first leading edge through wire 554a and the trailing edge through wire 558 are positioned along the chord 510 and the sheet body 505 is substantially symmetrical, applying tension to the subassembly 554 through the first leading edge through wire 554a may direct the sheet section 504 to assume a substantially neutral angle of attack. In another configuration, tension may be applied to the second leading edge through-wire 554b of the sub-assembly 554 and as such the position of the sheet section 504 may be defined by the cooperative effect of the second leading edge through-wire 554b and the trailing edge through-wire 558 on the sheet section 504. Since the second leading edge through-wire 554b is positioned above the chord 510 and the trailing edge through-wire 558 is positioned along the chord 510 and the sheet body 505 is substantially symmetrical, applying tension to the sub-assembly via the second leading edge through-wire 554b may direct the sheet section 504 to assume a substantially negative angle of attack. In another configuration, tension may be applied to the third leading edge through-wire 554c of the subassembly 554 and as such the position of the sheet section 504 may be defined by the cooperative effect of the third leading edge through-wire 554c and the trailing edge through-wire 558 on the sheet section 504. Since the third leading edge through-wire 554c is positioned below the chord 510 and the trailing edge through-wire 558 is positioned along the chord 510 and the sheet body 505 is substantially symmetrical, applying tension to the subassembly 554 through the third leading edge through-wire 554c may direct the sheet section 504 to assume a substantially positive angle of attack. Referring to Figure 5B, the foil system 500 of Figure 5A is shown with multiple foil sections 504 (e.g., foil sections 504a, 504b, 504c). Generally speaking, the number of foil sections 504 in the foil system 500 is scalable to accommodate a wide range of lift requirements, while offering very high aspect ratios and avoiding any additional ballast requirements. The foil sections 504 are capable of rotating in a flow field. The angle of attack at which the foil system 500 can reach equilibrium may be a function of the moment coefficient of the particular cross section of foil 504 used in conjunction with the relative comparative tensions and positions of the chord 512 established in the cable subassembly 554 with respect to the trailing edge through-cable 558.Accordingly, the magnitude of lift (positive or negative) generated by the sheet system 500 formed by the sheet sections 504 can also be controlled by several factors, including the following: Adjust the total length of the foil system 500 (e.g., the number of foil sections 504 threaded onto the various through-wires); Varying the chord length 512 of the sheet sections 504 (e.g., customizing the size of the sheet sections 504 at the time of manufacture to suit the required end application) and Choice of curvature for the foil profile of the 504 foil sections (smaller or larger 504 sections of the bulged foil depressor generate lower or higher lift coefficients, which includes adapting the profile to exhibit a substantially symmetrical or asymmetrical contour). In some cases, the foil system 500 may be a modular foil system. For example, multiple groups of foil sections may be connected together and optionally, may have separately controllable and manipulable angles of attack relative to other groups of foil sections in the system. The modular foil system offers a high degree of flexibility in the number of available options, including pivot location, pitch, chord length, and tail fin size and angle, to selectively adjust lift to suit operational specifications and requirements. Lift may also be adjusted by adjusting the tension in the cables passing through the foils. Modular foil systems applied to umbilicals or other similar type cables can also be scaled according to the quantity being deployed, for example by daisy-chaining foil systems at intervals. MA / IZ / ZUZZ / U0 / 40Z along the cable. As described herein, modular sheet systems, including various combinations of sheet sections, shapes, systems, etc., can be used to generate negative or positive lift (e.g., along a vertical direction) that depresses or maintains the components of a towed marine cable assembly at a submerged depth. Turning to Figure 6, another embodiment of the foil system 600 is shown. The foil system 600 may be substantially analogous to the foil system 500 described above with respect to Figures 5A and 5B. For example, the foil system 600 may be supported on a towed marine cable assembly by a group of through-cables. One or more actuators may be configured to selectively tension and manipulate a subset of through-cables disposed on front halves of the foil sections. This may define a rotational restraint of the front halves relative to the aft halves that may induce one or more of a positive, negative, and / or neutral angle of attack.In this regard, the sheet system may include sheet sections 604, a front half 606, a rear half 608, a leading edge 612, a trailing edge 616, a subset of through-leads 654, and a trailing edge through-lead 658, the redundant discussion of which is omitted here for clarity. Figure 6 shows the sheet system 600 in context MA / IZ / ZUZZ / U0 / 40Z schematic of a sample towed marine cable arrangement. For example, the trailing edge through-cable 658 may extend through each of the sheet sections 604 along the trailing edge 616. The trailing edge through-cable 658 may be connected to the towed marine cable assembly at a first connection 626a and at a second connection 626b, opposite the first connection 626a. For illustrative purposes, the connections 626a, 626b are shown as fixed connections. It will be appreciated that the connections 626a, 626b may be representative of substantially any appropriate component of a towed marine cable assembly, for securing the trailing halves of the sheet section 604 within the towed marine cable assembly.In some instances, the trailing edge through cable 658 may be coupled with an actuator and / or other device to adjust tension or otherwise manipulate the trailing edge through cable 658, however, this is not required. Figure 6 also shows the sheet system 600 held within the schematic context of the sample towed marine cable arrangement via the through-cable subassembly 654. The through-cable subassembly 654 extends generally adjacent the leading edge 612 of the sheet sections 604. The through-cable subassembly 654 is coupleable with a first actuator 670 at a first end of the sheet sections 604. The first actuator 670 may couple the through-cable subassembly 654 to the towed marine cable assembly via a first connection 624a. As further shown in Figure 6, the pass-through cable subassembly 654 may be coupled with a second actuator 680, opposite the first actuator 670. The second actuator 680 may couple the pass-through cable subassembly 654 to the towed marine cable assembly via a second connection 624b.Connections 624a, 624b may be representative of substantially any appropriate component of a towed marine cable assembly, for securing the rear halves of the sheet section 604 within the towed marine cable assembly. As described herein, the feed-through wire subset 654 may be manipulated to define a rotational restraint of the sheet sections 604 and induce an angle of attack. To facilitate this functionality, the first actuator 670 may be configured to increase or decrease the feed-through wire lengths within the forward feed-through wire subset 654, thereby inducing an initial tension distribution across the feed-through wire assembly 654 and 658. This initial tension distribution then defines a reference angle of attack for the sheet system 600 that may be further manipulated to change the rotational restraint to achieve a desired angle of attack. MA / IZ / ZUZZ / U0 / 40Z In this regard, the second actuator 680 may further manipulate the subset of through-wires 654 to define the rotational restraint. As further demonstrated by the exploded views of Figures 7A-7C below, the second actuator 680 may operate to channel and / or otherwise cause a selected through-wire from the subset of through-wires 654 to carry some, most, or substantially all of the tension initially applied by the first actuator 670 in the forward subset of through-wires 654, which in turn may cause the tension in the rearward through-wire 658 to increase or decrease as well. By applying tension to the selected one of the forward through-wires, a rotational restraint of the front halves 606 of the sheet sections 604 relative to the rearward halves 608 may be defined.And depending on the positional arrangement of the selected through-wires under the greatest tension, the sheet sections 604 may thus assume a positive, negative and / or neutral angle of attack, as described herein. Figures 7A-7C show sample enlarged schematic views of a sheet system 700. The sheet system 700 may be substantially analogous to the sheet system 600 of Figure 6 and thus include a sheet section 704, a leading edge 712, a trailing edge 716, a subset of through wires 754, a trailing edge through cable 758 and a second actuator 780. The redundant explanation of such features is omitted here for clarity. As illustrated in Figures 7A-7C, the dashed lines representing the feed-through wire subset 754 may correspond to three feed-through wires: a first leading edge feed-through wire 754a, a second leading edge feed-through wire 754b, and a third leading edge feed-through wire 754c. The first leading edge feed-through wire 754a, the second leading edge feed-through wire 754b, and the third leading edge feed-through wire 754c, may be substantially analogous to the first leading edge feed-through wire 554a, the second leading edge feed-through wire 554b, and the third leading edge feed-through wire 554c of Figure 5, and redundant discussion thereof is omitted herein for clarity. As shown in Figures 7A-7C, the second actuator 780 may be configured to manipulate the subset of through-wires 754 to define one or more of the first leading edge through-wire 754a, the second leading edge through-wire 754b, and the third leading edge through-wire 754c as the selected tensioned wire of the subset 754 defining the rotational restraint. In the embodiment of Figures 7A-7C, the second actuator 780 is schematically shown as a thumbwheel. The first cable MA / IZ / ZUZZ / U0 / 40Z leading edge through-wire 754a may be connected to the thumbwheel at a first connection 784a, the second leading edge through-wire 754b may be connected to the thumbwheel at a second connection 784b, and the third leading edge through-wire 754b may be connected to the thumbwheel at a third connection 784c. The thumbwheel may be configured to rotate, for example, in directions rl and r2 as shown in Figures 7A-7C. The thumbwheel 780 may rotate to define one of the first connection 784a, the second connection 784b, or the third connection 784c at a thumbwheel position most distal of the side edge 714 of the sheet section 704. More broadly, the thumbwheel may rotate to define one of the first connection 784a, the second connection 784b, or the third connection 784c as being furthest from the sheet section 704 at a distal point 786. In this regard, whichever feedthrough wire is connected via the most distal point 786 will carry all of the tension in the subset of the feedthrough wires.For example, because the distal point 786 is farther from the blade section 704, the end of the pass-through cable connected to the distal point 786 will be taut, while the other pass-through cables connected to the other connections (closer to the blade section 704) on the second actuator 780 may be slack or under less tension than the pass-through cable that is connected to the distal point 786 farther from the blade section 704. To illustrate the foregoing, Figure 7A shows the second actuator 780 in a configuration in which the thumbwheel is rotated to position the first connection 784a at the distal point 786. The first leading edge through-wire 754a is connected to the first connection 784a and, as such, in this configuration may define a rotational restraint of the blade section 704. As described above, the first leading edge through-wire 754a and the trailing edge through-wire 758 may be positioned along the chord of a substantially symmetrical blade shape. In this regard, in the configuration shown in Figure 7A, the blade section 704 may assume and / or maintain a substantially neutral angle of attack. Referring to Figure 7B, the second actuator 780 is shown in a configuration in which the selector wheel is rotated to position the second connection 784b at the distal point 786. The second leading-edge through-cable 754b is connected to the second connection 784b and, as such, in this configuration can define a rotational restraint of the blade section 704. As described above, the second leading-edge through-cable 754b is placed above the chord of a substantially symmetric blade shape, with the trailing-edge through-cable 758 positioned along the chord. In this configuration that MA / IZ / ZUZZ / U0 / 40Z shown in Figure 7B, the blade section 704 can assume and / or maintain a substantially negative angle of attack. Referring to Figure 7C, the second actuator 780 is shown in a configuration in which the thumbwheel is rotated to position the third connection 784c at the distal point 786. The third leading edge through-wire 754c is connected to the third connection 784c and as such, in this configuration may define a rotational restraint of the blade section 704. As described above, the third leading edge through-wire 754c is positioned below the chord of a substantially symmetrical blade shape, with the trailing edge through-wire 758 being positioned along the chord. In this configuration shown in Figure 7C, the blade section 704 may assume and / or maintain a substantially positive angle of attack. Turning to Figure 8, another embodiment of a sheet system 800 is shown. The sheet system 800 may be substantially analogous to the various sheet systems described herein and thus include a sheet section 804, a sheet body 805, a front half 806, a rear half 808, a chord 810, a leading edge 812, a trailing edge 816, a conduit 820a, a conduit 820b, a group of through cables 850, a leading edge through cable 854, and a trailing edge through cable 858. MA / IZ / ZUZZ / U0 / 40Z In this case, redundant explanation of these characteristics is omitted for clarity. In the embodiment of Figure 8, the wire harness 850 includes two wire harnesses: the leading edge wire harness 854 and the trailing edge wire harness 858. The leading edge wire harness 854 may be considered a subset of the wire harness 850. The leading edge wire harness 854 may be selectively tensioned and manipulated to define a rotational restraint of the front half 806 relative to the trailing half 808 of the sheet section 804. In some embodiments, a first actuator, such as the first actuator 670 of Figure 6 (not shown in Figure 8), may be used to apply tension to the leading edge wire harness 854. In conjunction with the tensioning of the leading edge through cable 854, a second actuator 880 may operate to move the leading edge through cable 854 relative to the chord 810. In this regard, the second actuator 880 may be a portion of a cam or cam assembly, operable to move the leading edge through cable 854 positionally within the sheet section 804. In some instances, the cam or cam feature may extend completely through the sheet section 804, between the lateral sides defining the cross section and defining a tube or guide within the body 805 of the sheet section 804. The ... MA / t / ZUZZ / UO / ^OZ cam feature can move the tube or guide in a rotatable manner, such as along a direction di and d2, as shown in Figure 8. The leading edge through wire 854 is positioned within the guide via conduit 820a. Therefore, when the guide moves, the leading edge through wire 854 can also move, such as to positions P1 and P2, as shown in Figure 8. The movement of the leading edge through wire 854 caused by the second actuator 880 may assist in inducing one or more angles of attack for the sheet section 804. For example, when the leading edge through wire 854 is positioned along the chord 810, as shown in FIG. 8 , the sheet section 804 may maintain a substantially neutral angle of attack, as described herein. Furthermore, when the leading edge through wire 854 is positioned above the chord 810, such as at substantially position P1 , the sheet section 804 may maintain a substantially negative angle of attack. Furthermore, when the leading edge through wire 854 is positioned below the chord 810, such as at substantially position P2 , the sheet section 804 may maintain a substantially positive angle of attack. The above embodiments are foil systems having foil sections with substantially symmetrical foil shapes. However, it will be appreciated that the present disclosure may be adapted to foil sections having a variety of different shapes, including foil sections that may be asymmetrical. For example, it may be desirable in certain circumstances to have a foil section with a preset or predetermined positive or negative lift, based on the application of the foil section in the towed marine cable assembly. This generally asymmetrical foil may be manipulated by a group of pass-through cables to maintain the foil at a positive, negative, and / or neutral angle of attack, using the techniques described herein. For illustrative purposes, Figure 9 depicts a sample asymmetric sheet 904 for use with one or more sheet systems of the present disclosure. The asymmetric sheet 904 may be substantially analogous to the sheet sections described herein, for example, and include a sheet body 905, a chord 910, a leading edge 912, a trailing edge 916, a first conduit 920a, a second conduit 920b, a third conduit 920c, and a fourth conduit 920d. Despite the foregoing similarities, the conduits 920a and 920d may be arranged through the sheet body 905 in a manner that takes into account the unique shape of the sheet section 904. In the sample illustration of Figure 9, the first conduit 920a and the fourth conduit 920d may be arranged substantially along the chord 910. The MA / IZ / ZUZZ / U0 / 40Z second conduit 920b may be disposed above chord 910 and third conduit 920d may be disposed below chord 910. To facilitate manipulation of sheet body 905, second conduit 920b and third conduit 920c may be separated by a lateral offset 913. The lateral offset may allow a sheet system to define a rotational restraint of the front half of the sheet section 904 relative to the rear half of the sheet section 904 in positions that account for the substantially asymmetric shape of the sheet body 905. In other instances, other configurations may be possible, including those in which the second conduit 920b and third conduit 920c are substantially aligned with each other, as well as other embodiments in which the second conduit 920b is closer to the leading edge 912 than the third conduit 920c. Figure 10 depicts a schematic illustration of another embodiment of a foil system of the present disclosure. The foil system 1000 may include a number of foil sections 1004. Each foil section 1004 has a span, a chord, and a foil cross-section, which may be a standard hydrofoil cross-section, such as those described above with respect to Figures 5A and 5B, or may be any other desired foil cross-section, such as those defined by NACA, Eppler, or Gottingen standards, or any other custom foil cross-section appropriate for the desired application, including substantially asymmetric foil shapes as described above with respect to Figure 9. The sheet sections 1004 may be arranged or stacked adjacent to one another. In this regard, the sheet sections 1004 may be a group of sheet sections that collectively define a sheet shape. The sheet shape may have a leading edge 1012 and a trailing edge 1008. The sheet shape of the sheet system 1000 may be arranged in a variety of orientations or angles of attack with respect to a fluid flow direction. This may cause the sheet system 1000 to generate lift that is used to manipulate components of a towed marine cable assembly (e.g., streamers, receivers, etc.) to steer, move, position, and / or depress the components, as may be appropriate for a particular application. In the embodiments of Figure 10, the sheet sections 1004 are coupled together using a pair of feed-through cables, such as a first feed-through cable 1026a and a second feed-through cable 1026b. The first feed-through cable 1026a and the second feed-through cable 1026b may extend through the sheet sections 1004, thereby supporting the sheet sections 1004 within the sheet system 1000. As an example, the sheet sections 1004 may define ducts or conduits that extend through the sheet sections 1004. Any number of ducts may extend along the length of the sheet sections within the front half of the sheet profile, with one or more ducts lying above the sheet chord line, above the chord line, or below the chord line. The stern duct is generally located on the foil chord line, just forward of the foil's trailing edge.In this embodiment, the position of the first feed-through cable 1026a may be selected prior to deployment to effect a particular set curvature for the sheet system 1000. The curvature for the sheet system 1000 may be changed prior to any particular deployment by changing the selection of the conduit in the front half of the sheet sections 1004 into which the first feed-through cable 1026a is threaded. Thus, the first through-cable 1026a may be positioned within and threaded through either of the forward conduits and the second through-cable 1026b may therefore be positioned within and threaded through the rear conduit of the sheet section 1004. In turn, the first through-cable 1026a and the second through-cable 1026b may be coupled to another component or assembly of a towed marine cable assembly and thereby assist in supporting the sheet sections 1004 with the assembly. In the embodiment of Figure 10, the first through-cable 1026a and the second through-cable 1026b may couple the sheet sections 1004 to connection points within a towed marine cable assembly. For example, Figure 10 shows a first connection point 1050 and a second connection point 1052. The first connection point 1050 and / or the second connection point 1052 may be a hook, a stay, a sheave, a fixed connection, and so forth of the towed marine cable arrangement, however, other configurations are possible. The connection points 1050, 1052 may generally define a module of a modular sheet system, and as such, other groups of sheet sections 1004 may be connected to one another at the connection points 1050, 1052. Each of the connection points 1050, 1052 may be coupled to various connecting cables. This may allow the sheet system to be coupled to substantially any other cable, rope, assembly, and so forth of the towed marine cable assembly, including seismic assembly components, a fishing net, and so forth. For example, Figure 10 shows a first connecting cable 1054 and a second connecting cable 1056 being coupled to respective connection points 1050, 1052. In turn, the first connecting cable 1054 and the second connecting cable 1056 may be coupled to other components of the towed marine cable assembly, in accordance with the embodiments described herein. In the embodiment shown in Figure 10, the feedthrough wires may converge at connection points adjacent opposite ends of the sheet sections 1004. For example, the first feedthrough wire 1026a and the second feedthrough wire 1026b may converge toward the first connection 1050. In addition, the first feedthrough wire 1026a and the second feedthrough wire 1026b may converge toward the second connection 1052. This may allow for more precise or accurate control of the orientation of the sheet sections 1004. For example, the first pass-through cable 1026a may extend from the first connection point 1050 to the second connection point 1052. Between the first connection point 1050 and the second connection point 1052, the first pass-through cable 1026a may extend through a conduit of the sheet sections 1004 (e.g., a conduit defined along and just behind the leading edge 1012). The second pass-through cable 1026b may extend from the first connection point 1050 to the second connection point 1052. Between the first connection point 1050 and the second connection point 1052, the second pass-through cable 1026b may extend through a conduit of the sheet sections 1004 (e.g., a conduit defined along and just forward of the trailing edge 1008). The position or orientation or catenary of the sheet assembly is defined by (or restricted by) the through cables 1026a, 1026b. For example, the foil assembly (composed of all of the individual foil sections 1004) may be subjected to hydrodynamic forces and will therefore respond and move to find an equilibrium profile, and a catenary can be articulated from one foil section to the next so that not all foil sections need to assume the same angle of attack. However, by acting in unison, the foil assembly will generate a certain amount of lift and drag according to the hydrodynamic characteristics of the foil. By altering the tension in one or both of the cables 1026a, 1026b, the cables 1026a, 1026b will allow the foil assembly to find a new equilibrium profile which may also alter (increase or decrease) the total amount of lift being generated. In certain embodiments, tension may be increased in one or both of the through-wires 1026a, 1026b to adjust the angle of attack of the foil shape. As one possibility, an increase in tension in the through-wire closest to the leading edge will result in a net decrease in the angle of attack, which, in turn, will result in a decrease in the total amount of lift produced by the foil assembly as a whole. Alternatively, a decrease in tension in the forward through-wire will result in an increase in the overall angle of attack of the foil assembly. The increased overall angle of attack may result in MA / IZ / ZUZZ / U0 / 40Z that the foil system 1000 generates additional lift. As such, the tension of one or both of the through cables 1026a, 1026b (or any other cables or strings supporting the foil sections 1004 within the arrangement) can be adjusted to manipulate the lift generated by the foil system 1000. The total amount of lift generated by the foil assembly will depend on the cross-sectional profile of the foil, as well as the tension and location of the front through cable which is positioned within the front half of the foil section. To facilitate the foregoing, Figure 10 represents embodiments in which the first and second feedthrough cables 1026a, 1026b converge at connection points 1050, 1052, which are adjacent to opposite ends of the sheet system 1000. The convergence of the feedthrough cables 1026a, 1026b to common connection points 1050, 1052, may allow an actuator to control the tension in one or both of the feedthrough cables 1026a, 1026b in a precise, accurate, and potentially dynamic manner. In this regard, Figure 10 shows the sheet system 1000 including an actuator 1024. The actuator 1024 can be used to adjust the tension in one or both of the first through wire 1026a or the second through wire 1026b, which, in turn, can adjust the angle of attack of a sheet shape defined by the sheet section 1004. The actuator 1024 is MA / IZ / ZUZZ / U0 / 40Z is shown in Figure 10 coupled or positioned on the first through cable 1026a at a first end 1016 of the sheet system 1000. Positioning the actuator 1024 on the first through cable 1026a may help orient the leading edge 1012 in one or more directions to generate a target lift for the sheet system 1000. In other cases, the actuators may be arranged in various other positions of the sheet system 1000, including positioning on the second through cable 1026b, for example, as shown with another actuator 1024 (shown in dashed lines). The actuator 1024 may be substantially any appropriate component used to adjust the tension in a cable, including the first actuator 670 and 680 of Figure 6 and variations thereof, as described herein. Additionally or alternatively, the actuator may be a mechanical component, such as a tensioner. The tensioner may be manually adjusted, for example, prior to deployment of the array, to establish the desired angle of attack of the foils. Additionally or alternatively, the foil system may include various dynamic actuators, such as a pneumatic or electromechanical controller that is used to modify the tension in the through-cable pair, for example, as described in U.S. Patent Application Publication No. 20170106946A1. However, it will be appreciated that other actuators are possible and are contemplated within the scope of the invention. MA / IZ / ZUZZ / U0 / 40Z present description. In some cases, the actuator can be configured to adjust the tension of the cable while the array is deployed in a marine environment. For example, the actuator can be configured to receive a signal from another source, such as a vessel towing the array or another remote source. The actuator can use the signal to adjust the tension in the cable. For example, in a first configuration, the signal can be indicative of a first desired orientation, and the actuator can adjust the tension in the through-cable so that the foil section matches the first desired orientation. Likewise, in another configuration, the signal can be indicative of a second desired orientation, and the actuator can adjust the tension in the through-cable so that the foil section matches the second desired orientation.In this regard, the actuator 1024 may be, more broadly, a component of the adjustment mechanism (e.g., adjustment mechanism 450 of Figure 4) or other steering or positioning system described herein. To facilitate the reader's understanding of the various functionalities of the embodiments discussed herein, reference is now made to the flowchart in Figure 11, which illustrates process 1100. While specific steps (and orders of steps) of the methods presented here have been illustrated and will be discussed, other methods (including more, MA / IZ / ZUZZ / U0 / 40Z less or different steps than those illustrated) consistent with the teachings disclosed herein are also contemplated and encompassed by the present disclosure. In this regard, with reference to Figure 11, process 1100 may be used with any of the sheet systems and towed marine cable assemblies described herein. In operation 1103, prior to launch, a foil assembly is manipulated and configured for deployment with the marine array. The lengths of the through-conduits are adjusted using best engineering judgment to achieve eventual target positions once deployed. In operation 1104, an array is launched into a marine environment. The array may include a cable configured to carry a submerged payload and a foil system coupled to the cable. The foil system includes a group of foil sections that may each define front and rear halves and are connected together by a group of through-cables extending therethrough. For example, and referring to Figures 5A and 5B, each of the foil sections 504 may have front halves 506 and rear halves 508. The foil section 504 may be connected together via the group of through-cables 550. In operation 1105, measurements are acquired to determine whether the array is positioned in the marine environment in accordance with operational objectives, specifications and tolerances. If all positions are within specified tolerances, then execution proceeds to operation 1106 where an appropriate wait time is assigned before returning to operation 1105 for an updated evaluation. If the array position is not within specified tolerances, then the logic flow proceeds to operation 1107 where algorithms are used to determine which through-wire(s) need adjustment and how much tension adjustment will be required to bring the array position back within the specified tolerance. Moving on to operation 1108, the necessary tension adjustments are implemented to the first of one or more through-wires in the group of through-wires. This tensioning in operation 1108 may define a first rotational restraint of the front halves relative to the rear halves, thereby inducing a first angle of attack.For example, and referring to Figures 5A, 5B and 6, a first through-wire of the through-wire subset 554 may be tensioned. One or more actuators, such as the second actuator 680, may apply tension across the first of the through-wires to define a rotational restraint of the front halves 606 relative to the rear halves 608. This may induce a particular angle of attack. For example, when the tensioned through-wire is the first through-wire 554a, the sheet section 504 may assume a substantially neutral angle of attack. Furthermore, when the tensioned through-wire is the tensioned through-wire 554b, the sheet section 504 may assume a substantially negative angle of attack. Furthermore, when the tensioned through-wire is the third through-wire 554c, the sheet section 504 may assume a substantially positive angle of attack. Operation 1108 includes a time-out interval to allow the array sufficient time to reach a new equilibrium position. It should be understood that each cycle through operations 1107 and 1108 may include one or more actuators controlling one or more feed-through cables in one or more modular sheet systems. For example, and with reference to Figures 5A, 5B and 6, a second feed-through cable of the feed-through cable subset 554 may be tensioned. One or more actuators, such as second actuator 680, may apply tension across the second of the feed-through cables to define a rotational restraint of the front halves 606 of the sheet sections 604 relative to the rear halves 608. This may induce a given angle of attack. For example, when the tensioned feed-through cable is the first feed-through cable 554a, the sheet section 504 may assume a substantially neutral angle of attack.Furthermore, when the tensioned through-wire is tensioned through-wire 554b, the sheet section 504 may assume a substantially negative angle of attack. Furthermore, when the tensioned through-wire is the third through-wire 554c, the sheet section 504 may assume a substantially positive angle of attack. With respect to operations 1107 and 1108, a tensioned cable of the group of through cables may be offset from a chord defined between a leading edge and a trailing edge of either of the sheet sections (e.g., second and / or third through cables 554b, 554). Additionally or alternatively, the tensioning of the group of through cables may be substantially in line with the chord (e.g., first through cable 554a), as described herein. Figure 12 depicts another embodiment of a towed marine cable assembly. In particular, Figure 12 shows a towed marine cable array 1200. The towed marine cable array 1200, as within any of the towed marine cable assemblies described herein, may be or be associated with a seismic array, a fishing trawl, a military application, an oceanographic survey, and / or substantially any other maritime application. The embodiment of Figure 12 shows the towed marine cable assembly having a towed cable and a payload that is steered or positioned within a marine environment by a sheet system offset to starboard and port. To facilitate the above, the towed marine cable assembly 1200 includes a vessel 1202. The vessel 1202 is shown positioned along the surface of a MA / IZ / ZUZZ / U0 / 40Z marine environment 1204. Attached to the vessel 1202 is a tow cable 1206. The tow cable 1206 can be towed through the marine environment 1204 by the vessel 1202. The tow cable 1206 can carry or pull a towed body or other payload 1208 through the marine environment 1204. In some instances, the towed body 1208 can pull a transmission cable 1214 through the marine environment 1204. It may be desirable to steer, position, stabilize, etc., the towed body 1208 and associated components within the marine environment 1204. In this regard, Figure 12 shows the towed marine cable assembly 1200 including a first foil system 1210 and a second foil system 1212 coupled with the towed cable 1206. The first foil system 1210 and the second foil system 1212 may be substantially analogous to any of the foil systems described herein. As such, the first foil system 1210 and the second foil system 1212 may each include a group of foil sections that collectively define an angle of attack and, therefore, may be configured to generate lift. In one embodiment, the first foil system 1210 may have an angle of attack that causes the first foil system 1210 to generate lift that deflects the towed cable 1206 toward a starboard direction. In addition, the second foil system 1212 may have an angle of attack that causes the second foil system 1212 to generate lift that deflects the towed cable 1206 toward a port direction. In this regard, the first foil system 1210 and the second foil system 1212 may counteract each other and thereby help stabilize or otherwise control the position of the towed body 1208 in the marine environment 1204. In some instances, the angle of attack of one or both of the first foil system 1210 and the second foil system 1212 may have an adjustable angle of attack, which can be manipulated to help steer the towed body 1208, as appropriate for a given application. Other examples and implementations are within the scope and spirit of the appended description and claims. For example, features implementing functions may also be physically located at various locations, including distribution such that portions of the functions are implemented at different physical locations. Furthermore, as used herein, including in the claims, or as used in a list of items preceded by at least one of indicates a disjunctive listing such that, for example, a listing of at least one of A, B, or C means AoBoCoABoACoBCoABC (i.e., A and Band C). Furthermore, the term exemplary does not mean that the described example is preferred or better than other examples. MA / IZ / ZUZZ / U0 / 40Z The foregoing description, for explanatory purposes, uses specific nomenclature to provide a complete understanding of the described embodiments. However, it will be apparent to those skilled in the art that no specific details are required to implement the described embodiments. Therefore, the foregoing descriptions of the specific embodiments described herein are presented for illustrative and descriptive purposes. They are not intended to be exhaustive or to limit the embodiments to the precise forms described. It will be apparent to those skilled in the art that many modifications and variations are possible in light of the foregoing teachings.

Claims

1. A towed marine cable assembly comprising a cable configured to be towed by a vessel to transport a submerged payload through a marine environment and a foil system coupled to the cable and configured to deflect the submerged payload toward a target position, the foil system including a group of foil sections each having a leading edge collectively defining an angle of attack and a group of through cables supporting the group of foil sections within the foil system, wherein a subset of through cables of the group of through cables is: disposed on co-halves of the group of foil sections; selectively tensionable and manipulable to define a tensioned through cable of the subset of through cables as offset from a tether that is defined between the leading edge and the trailing edge of any one of the foil sections.

2. The towed marine cable assembly of claim 1, further comprising an actuator operatively coupled to the through-cable subassembly and configured to alter tension in one or more MA / IZ / ZUZZ / U0 / 40Z through-cable cables of the through-cable subassembly.

3. The towed marine cable assembly of claim 2, wherein the through-cable subassembly is disposed across front halves of the sheet section group, wherein: the actuator is a first actuator and the marine cable assembly further comprises a second actuator operatively coupled to the through-cable subassembly and configured to manipulate the tensioned through-cable in an arrangement that rotationally restrains the front halves relative to the rear halves of the sheet section group.

4. The towed marine cable assembly of claim 1, characterized in that the sub-assembly of through cables comprises a group of leading edge through cables, each of which extends through front halves of the group of sheet sections and along the leading edge and the sub-assembly of through cables further comprises a trailing edge through cable disposed through rear halves of the group of sheet sections and along the trailing edge.

5. The towed marine cable assembly of claim 4, characterized in that a first leading edge through-cable of the leading edge through-cable group 76 and the trailing edge through-cable are arranged substantially along the rope.

6. The towed marine cable assembly of claim 5, characterized in that a second leading edge through cable is disposed above the strand and a third leading edge through cable is disposed below the rope.

7. The towed marine cable assembly of claim 6, characterized in that: in a first configuration, the tensioned through cable is the second through cable of the leading edge and in a second configuration, the tensioned through cable is the third through cable of the leading edge.

8. The towed marine cable assembly of claim 1, wherein the subset of through cables is disposed across front halves of the group of sheet sections and wherein: each sheet section of the group of sheet sections is substantially symmetrical along the chord; the group of sheet sections exhibits a substantially neutral angle of attack when the cable subset is in a relaxed state and when the tensioned through cable is displaced from the chord, the tensioned through cable rotationally restrains the front halves relative to the rear halves of the group of sheet sections to define the angle of attack as a positive or negative angle of attack.

9. The towed marine cable assembly of claim 1, characterized in that the subset of through cables can be further manipulated to define the through cable tensioned to be along the rope, thereby maintaining the angle of attack as a substantially neutral angle of attack.

10. The towed marine cable assembly of claim 1, characterized in that the sheet system comprises a first modular sheet system; the marine cable assembly further comprises a second modular sheet system, according to the sheet system of claim 1, and the first and second modular sheet systems are connected to each other within the marine cable network.

11. The towed marine cable assembly of claim 10, characterized in that the group of through cables of each of the first and second modular sheet systems converge toward a connection point disposed substantially between the first and second modular sheet systems.

12. The towed marine cable assembly of the MA / IZ / ZUZZ / U0 / 40Z 78 claim 10, characterized in that the cable is an upper cable; the marine cable assembly further includes a lower cable; the second modular sheet system is connected to the lower cable and the upper cable and the lower cable cooperate to form the mouth of a fishing net.

13. The towed marine cable assembly of claim 12, characterized in that the first modular sheet system and the second modular sheet system are configured to increase the separation distance between the upper cable and the lower cable at the mouth of the trawl.

14. The towed marine cable assembly of claim 13, wherein the marine cable assembly further comprises a port cable and a starboard cable that additionally form the mouth of the trawl net; a third modular sheet system, according to the modular sheet system of claim 1, attached to the port cable; and a fourth modular sheet system, according to the modular sheet system of claim 1, attached to the starboard cable; wherein the third modular sheet system and the fourth modular sheet system are configured to laterally separate the port cable and the starboard cable.

15. The towed marine cable assembly of claim 1, characterized in that the cable is a component of a seismic receiver assembly.

16. The towed marine cable assembly of claim 15, characterized in that the submerged payload includes seismic sources, the seismic sources configured to emit energy to the marine environment.

17. The towed marine cable assembly of claim 1, wherein the cable is a spreader cable; the marine cable assembly further comprises transmission cables configured to be towed behind the spreader cable; the submerged payload includes seismic receivers carried by the transmission cables; and the angle of attack is configured to maintain the seismic receivers at the desired depth.

18. The towed marine cable assembly of claim 1, wherein the cable is a side cable of the tensioned marine cable arrangement; the side cable includes an end portion positioned ML / t / ZUZZ / UO / ^OZ along an edge of the marine cable assembly, and the sheet system is coupled to the side cable adjacent to the end portion.

19. The towed marine cable assembly of claim 18, characterized in that the marine cable assembly further comprises a branch line connected to the end portion of the side cable and the sheet system is connected to the branch line opposite the side cable.

20. A foil system for deflecting a cable of a towed marine assembly, characterized in that it comprises a foil defining a foil shape having a leading edge and a trailing edge; a first through cable extending through the foil along the leading edge; a second through cable extending through the foil along the trailing edge; a first actuator configured to tension the first through cable and a second actuator configured to move the tensioned first through cable from an unselected configuration to a selected configuration, wherein when in the unselected configuration, the tensioned first through cable cooperates with the second through cable to maintain the foil at a substantially neutral angle of attack and when in the selected configuration, the tensioned first through cable cooperates with the second through cable to maintain the foil at a positive or negative angle of attack.

21. The sheet system of claim 20, characterized in that the sheet is substantially symmetrical and defines a chord extending between the leading and trailing edges.

22. The sheet system of claim 21, characterized in that the first tensioned through-wire is arranged offset from the rope in the selected configuration.

23. The sheet system of claim 22, wherein the second actuator is coupled to the sheet and the tensioned first through-wire and is configured to move the tensioned first through-wire from a substantially chord-length arrangement in the non-selected configuration to the offset chord arrangement in the selected configuration.

24. The sheet system of claim 20, characterized in that the first through-wire is a first leading edge through-wire of a group of leading edge through-wires extending through a front half of the sheet and along the leading edge.

25. The sheet system of claim 24, characterized in that the second actuator is configured to define one of the group of leading edge through-wires as the first tensioned through-wire.

26. The sheet system of claim 25, wherein the second actuator comprises a selector wheel; each of the group of leading edge through-wires is secured to the selector wheel at circumferentially spaced-apart positions, and a rotational position of the selector wheel defines which of the group of leading edge through-wires is the first tensioned through-wire.

27. The foil system of claim 26, characterized in that the rotation position of the thumbwheel is adjustable while the foil system is submerged in a marine environment.

28. The sheet system of claim 24, wherein the front half of the sheet includes a first conduit, a second conduit, and a third conduit, each configured to receive a different leading edge feed-through cable from the group of leading edge feed-through cables, and the sheet further defines a rear half having a fourth conduit configured to receive the second feed-through cable, each of the first, second, third, and fourth conduits extending the full width of the sheet and disposed substantially parallel to each other.

29. The sheet system of claim 20, characterized in that the first through-wire and the second through-wire converge toward connection points adjacent to opposite ends of the sheet.

30. The foil system of claim 29, characterized in that each of the connection points is configured to couple a pair of through-cables of another foil system of the towed marine assembly to the first and second through-cables.

31. A method, characterized in that it comprises: launching an assembly into a marine environment, the assembly comprising a cable configured to transport a submerged payload and a foil system coupled to the cable, the foil system including a group of foil sections, each of which defines front and rear halves and connected to each other by a group of pass-through cables extending therethrough;tensioning the first of one or more through-strands of the group of through-strands to define a first rotational restraint of the front halves relative to the rear halves, thereby inducing a first angle of attack, and tensioning a second of one or more through-strands of the group of through-strands to define a second rotational restraint of the front halves relative to the rear halves, thereby inducing a second angle of attack, wherein a tensioned through-strand of the group of through-strands during any of the tensioning operations is displaced or deflected from a chord defined between a leading and a trailing edge of at least one of the sheet sections; 32. The method of claim 31, further comprising acquiring submerged positional data associated with the foil system and determining an adjustment parameter for the foil system by comparing the submerged positional data to an operational target.

33. The method of claim 32, characterized in that the operation of inducing the first angle of attack or the operation of inducing the second angle of attack is based on the adjustment parameter.

34. The method of claim 33, wherein the foil system further comprises a dynamic actuator configured to cause any of the tensioning operations while the arrangement is submerged in the marine environment using the adjustment parameter.

35. The method of claim 31, characterized in that one of the first or second angles of attack is a substantially neutral angle of attack.

36. The method of claim 35, characterized in that each of the group of sheet sections comprises a substantially symmetrical sheet.

37. The method of claim 31, wherein: the group of through-wires comprises a group of leading edge through-wires, each spaced apart from one another and extending through first halves of the group of sheet sections along leading edges of the group of sheet sections; one of the tensioning operations defines a first leading edge through-wire of the group of leading edge through-wires as the tensioning of the group of leading edge through-wires, and another of the tensioning operations defines a second leading edge through-wire of the group of leading edge through-wires as the tensioning of the group of leading edge through-wires.

38. The method of claim 37, further comprising tensioning a third of the one or more lead wires, the third lead wire of the leading edge being disposed substantially along the rope.

39. The method of claim 31, characterized in that the array is a seismic array. MA / IZ / ZUZZ / U0 / 40Z 40. The method of claim 39, characterized in that the seismic array comprises seismic sources and seismic receivers that cooperate to produce geological data.

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