Sonar Dome

Abstract

To provide an FRP dome body of a sonar dome advantageous for obtaining protection for a transducer by suppressing damage of the dome body during high speed navigation of a vessel.SOLUTION: A dome body 18 is composed including an inner FRP plate 20, an outer FRP plate 22, an interior rubber layer 24 and an anti-staining rubber layer 26. The inner FRP plate 20 forms a section of the dome body 18 positioned on a transducer 12 side. The outer FRP plate 22 forms a section of the dome body 18 positioned opposite to the transducer 12. The interior rubber layer 24 is arranged between the inner FRP plate 20 and the outer FRP plate 22.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sonar dome that covers a transducer installed on the bottom of a ship and protects the transducer from noise generated from the ship itself. [Background technology]

[0002] The sonar dome includes a bead portion having a core material and a dome body extending from the bead portion. The sonar dome is installed on the bottom of the ship by attaching the bead part to the hull. Such sonar domes are conventionally made of rubber (see US Pat. No. 5,399,313). As a result, as ships have become faster in recent years, the fluid resistance acting on the body of the sonar dome has increased when traveling at high speeds, causing deformation of the dome body and resulting in problems such as increased resistance at the bottom of the ship. Therefore, the present inventors have proposed a sonar dome made of FRP that can prevent deformation during high-speed navigation, and this FRP sonar dome has a dome body that includes an FRP plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication 2012-111310 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, if the dome body is made entirely of FRP plates, when a floating object collides with the dome body during high-speed navigation, the dome body is easily damaged by the impact, which is disadvantageous in terms of protecting the transducer. The present invention has been devised in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a dome body for a sonar dome that can suppress damage to the FRP dome body during high-speed navigation and is advantageous in protecting the transducer. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, one embodiment of the present invention is a sonar dome comprising a bead portion attached to the bottom of a vessel, and a dome body extending from the bead portion and covering a transducer installed on the bottom of the vessel, wherein the dome body is characterized in that it is comprised of an inner FRP plate that forms the portion of the dome body located on the transducer side, an outer FRP plate that forms the portion of the dome body located opposite the transducer, and an internal rubber layer having a shock absorbing function that is disposed between the inner and outer FRP plates. In addition, one embodiment of the present invention is characterized in that the dome body further includes an anti-fouling rubber layer that is attached to the surface of the outer FRP plate opposite the inner rubber layer and has an anti-fouling function and an impact absorbing function. Furthermore, one embodiment of the present invention is characterized in that the bead portion is formed including a core material, a first FRP plate is hung on the core material at the bead portion and folded back, and the inner FRP plate and the outer FRP plate are formed from the folded back first FRP plate. Furthermore, one embodiment of the present invention is characterized in that the bead portion and the portion of the dome body near the bead portion serve as an attachment base supported by an attachment fixture on the bottom of the ship, and in the bead portion, a second FRP plate is hung on the core material inside the first FRP plate and folded back, and the portion of the dome body exposed from the attachment fixture, near the attachment fixture, is overlapped with the folded second FRP plate in two and placed in place of the internal rubber layer. Furthermore, one embodiment of the present invention is characterized in that, in the bead portion, a third FRP plate is hung on the core material and folded back on the outside of the first FRP plate, and at the part of the dome main body exposed from the mounting fixture, the folded-back third FRP plate is arranged on the surface of the inner FRP plate facing the transducer and the surface of the outer FRP plate facing away from the transducer. Effect of the Invention

[0006] According to one embodiment of the present invention, if a floating object collides with the dome body while a ship is traveling at high speed, the impact can be absorbed by the internal rubber layer, which is advantageous in minimizing damage to the outer FRP plate and protecting the transducer compared to a case in which the dome body is constructed by stacking two FRP plates. Furthermore, compared to constructing the dome body by stacking two FRP plates, the increased sound transmittance allows for more efficient transmission and reception of waves, which is advantageous for detecting objects with high accuracy. In addition, since the vulcanization can be carried out in separate steps, it is advantageous in shortening the exposure time of the prepregs for forming the outer FRP plate and the prepregs for forming the inner FRP plate, which is advantageous in manufacturing the sonar dome 14 easily and reliably. Furthermore, according to one embodiment of the present invention, providing an anti-fouling rubber layer on the outer FRP plate can prevent marine organisms from adhering to the dome body, which is advantageous in ensuring the acoustic transparency of the dome body; and if floating objects collide with the dome body when the ship is traveling at high speed, the anti-fouling rubber layer can also absorb the impact, which is advantageous in minimizing damage to the outer FRP plate and protecting the transducer. Furthermore, according to one embodiment of the present invention, the inner FRP plate and the outer FRP plate connected to the core material can be easily formed by the first FRP plate that is hung on the core material at the bead portion and folded back. Furthermore, according to one embodiment of the present invention, placing a second FRP plate instead of an internal rubber layer in the portion of the dome body near the mounting fixture that is exposed from the mounting fixture is advantageous in ensuring the strength of the portion of the dome body that is subjected to a large bending moment when the ship is traveling at high speed, and is advantageous in increasing the durability of the sonar dome. In addition, according to one embodiment of the present invention, at the portion of the dome body near the mounting fixture that is exposed from the mounting fixture, a third FRP plate is placed on the surface of the inner FRP plate facing the transducer and on the surface of the outer FRP plate facing away from the transducer, which is advantageous in ensuring the strength of the portion of the dome body that is subjected to a large bending moment when the ship is traveling at high speed, and is further advantageous in increasing the durability of the sonar dome. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a side view of the sonar dome placed on the bottom of the vessel. [Diagram 2] (A) is a plan view of the sonar dome, (B) is a side view, and (C) is a perspective view. [Diagram 3] FIG. 2 is a cross-sectional view of a dome body according to the first embodiment. [Figure 4] 2 is a cross-sectional view of the sonar dome of the first embodiment attached to the bottom of a ship. FIG. [Diagram 5] 11 is a cross-sectional view of a sonar dome according to a second embodiment attached to the bottom of a ship. FIG. [Figure 6] FIG. 11 is a cross-sectional view showing a state in which a sonar dome according to a third embodiment is attached to a ship bottom. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the first embodiment will be described with reference to FIGS. As shown in FIG. 1, a transducer 12 is installed on the bottom of a ship 10, and a sonar dome 14 is provided to cover the transducer 12. As shown in FIG. 2, the sonar dome 14 has an elongated shape extending along the extension direction of the ship, and is open at the top. As shown in Figures 2(A) and (C), when viewed in a plan view, the outline of sonar dome 14 is formed by semicircular arc portions at both ends in the longitudinal direction and two opposing straight lines connecting the ends of the semicircular arc portions. Also, as shown in Figure 2 (B), when viewed from the side, the height of sonar dome 14 is greatest at the center in the longitudinal direction and gradually decreases toward both ends, and the height of sonar dome 14 viewed from the longitudinal direction is greatest at the center in the width direction (not shown) and gradually decreases toward the outside in the width direction. The sonar dome 14 includes a bead portion 16 and a dome body 18 that extends in a dome shape. The bead portion 16 is attached around its entire periphery to the ship bottom 10 and serves to maintain the shape of the sonar dome 14, and extends around the entire upper edge of the dome body 18A.

[0009] As shown in FIG. 3, the dome body 18 includes an inner FRP (Fiber Reinforced Plastics) plate 20, an outer FRP plate 22, an inner rubber layer 24, and an antifouling rubber layer . The inner FRP plate 20 forms the portion of the dome body 18 located on the transducer 12 side. The inner rubber layer 24 is provided on the surface of the inner FRP plate 20 opposite the transducer 12 . The inner rubber layer 24 is made of a rubber material having a shock absorbing function. The outer FRP plate 22 is provided on the surface of the inner rubber layer 24 located opposite the inner FRP plate 20 . Thus, the outer FRP plate 22 forms the portion of the dome body 18 opposite the transducer 12, and the inner rubber layer 24 is sandwiched between the inner FRP plate 20 and the outer FRP plate 22. The stain-resistant rubber layer 26 is provided as necessary, and is provided on the surface of the outer FRP plate 22 opposite the inner rubber layer 24 . The antifouling rubber layer 26 has an antifouling function that prevents marine organisms from attaching to the outer FRP plate 22, and a shock absorbing function.

[0010] Next, the attachment of the sonar dome 14 to the bottom of the vessel 10 will be described. As shown in FIG. 4, the bead portion 16 is configured to include a core material . The core material 28 extends around the entire upper edge of the dome body 18 . The core material 28 may be made of various flexible materials known in the art, such as one or more flexible wires coated in a circular shape with rubber, or a flexible rope made of synthetic fibers coated in a circular shape with rubber.

[0011] In addition to the core material 28, the bead portion 16 is configured to include an outer peripheral rubber layer 32, a first FRP plate 34, a seal rubber layer 36, and a gap blocking rubber 38A. The peripheral rubber layer 32 covers the peripheral surface of the core material 28 . The first FRP plate 34 is placed over the core material 28 from above the outer rubber layer 32 and folded back, extending from the bead portion 16 to the dome body 18, and the two folded back first FRP plates 34 respectively constitute the inner FRP plate 20 and the outer FRP plate 22 in the dome body 18. That is, the inner FRP plate 20 and the outer FRP plate 22 connected to the core material 28 can be easily formed by the first FRP plate 34 that is hung on the core material 28 at the bead portion 16 and folded back. The sealing rubber layer 36 is provided to reliably hold the sonar dome 14, including the bead portion 16, on the bottom of the vessel 10 while ensuring sealing properties; more specifically, it is provided to cover the bead portion 16, which is the portion that is attached to the bottom of the vessel 10, and the portion of the first FRP plate 34 near the bead portion 16. As shown in FIG. 4, if the portion of the sonar dome 14 that is attached to the bottom of the vessel 10 is referred to as the mounting base 1402, the mounting base 1402 is configured to include the bead portion 16 and the portion of the dome body 18 close to the bead portion 16, and the sealing rubber layer 36 is provided on the mounting base 1402.

[0012] The gap blocking rubber 38A is pre-vulcanized and molded with a cross-sectional shape whose thickness gradually decreases with increasing distance from the core material 28, and blocks the gaps formed between the core material 28 and the two first FRP plates 34 folded back from the core material 28. In this embodiment, since the core material 28 is covered with the peripheral rubber layer 32, the gap blocking rubber 38A is pre-vulcanized and molded in a cross-sectional shape that blocks the gaps formed between the peripheral rubber layer 32 and the two first FRP plates 34 folded back from the peripheral rubber layer 32, thereby blocking the gaps. A large tensile force acts on the dome body 18 when the ship is traveling at high speed, and the gap blocking rubber 38A is located in a portion of the first FRP plate 34 that receives this large tensile force, so it is made of hard rubber so that it will not deform even when subjected to a large force. The bead portion 16 is the portion of the sonar dome 14 located around the core material 28, and in this embodiment, the bead portion 16 is composed of the core material 28, the peripheral rubber layer 32, the gap blocking rubber 38A, and the portion of the first FRP plate 34 and the sealing rubber layer 36 that are located around the core material 28, the peripheral rubber layer 32, and the gap blocking rubber 38A, and the dome body 18 refers to the portion of the sonar dome 14 excluding the bead portion 16. Furthermore, the cross-sectional shape of the mounting base 1402 cut on a plane perpendicular to the extension direction of the core material 28 is formed symmetrically with respect to imaginary line C connecting the center of the core material 28 and the center of the thickness of the dome body 18 near the bead portion 16. Therefore, when a large tensile force acts on the core material 28 from the first FRP plate 34 at the mounting base 1402 when the ship is traveling at high speed, this tensile force does not act in a direction that rotates the core material 28, which is advantageous in terms of increasing the durability of the mounting base 1402 including the bead portion 16.

[0013] As shown in FIG. 4, the sonar dome 14 is attached to the bottom of the vessel 10 via a mounting member 42, a bead seat 44 as a mounting fixture, and a bead clamp 46. The mounting member 42 is a plate-like member attached to the bottom of the ship 10, and extends in the shape of a long, thin frame around the transducer 12 and following the shape of the sonar dome 14 in a plan view. The mounting member 42 is made of metal or synthetic resin. The bead seat 44 extends in an elongated frame shape corresponding to the shape of the bead portion 16 in a plan view. The bead seat 44 is made of metal or synthetic resin, and has a bead seat side mating surface 4402 and a bead seat side clamping surface 4404 . The bead clamp 46 extends around the entire periphery of the bead seat 44 . The bead clamp 46 is made of metal or synthetic resin, and includes a bead clamp side mating surface 4602 and a bead clamp side clamping surface 4604 .

[0014] When attaching the sonar dome 14 to the bottom of the vessel 10, the bead sheet side clamping surface 4404 of the bead sheet 44 and the bead clamp side clamping surface 4604 of the bead clamp 46 are aligned with the mounting base 1402 of the sonar dome 14, the bead sheet side mating surface 4402 of the bead sheet 44 and the bead clamp side mating surface 4602 of the bead clamp 46 are aligned, the bead clamp 46 and the bead sheet 44 are fastened together with the first bolt B1, and the mounting base 1402 of the sonar dome 14 is clamped by the bead sheet side clamping surface 4404 and the bead clamp side clamping surface 4604. Then, the upper surface of the bead seat 44 is aligned with the lower surface of the mounting member 42 attached to the bottom of the vessel 10, and the bead seat 44 is attached to the mounting member 42 with the second bolt B2, thereby positioning the sonar dome 14 on the bottom of the vessel 10. That is, the bead seat 44 and the bead clamp 46 form a mounting fixture 48 that supports the mounting base 1402 of the sonar dome 14 .

[0015] Next, a method for manufacturing the sonar dome 14 will be described. First, the mounting base 1402 and the surrounding area of ​​the dome body 18 will be described. The mounting base 1402 and the adjacent portion of the dome body 18 are manufactured in sequence at predetermined intervals along the extension direction of the bead portion 16 and at predetermined intervals along a predetermined width perpendicular to this length. That is, a strip of unvulcanized rubber for forming the peripheral rubber layer 32 is wound around each predetermined length of the core material 28 . Next, an end portion of the gap blocking rubber 38A that has been previously vulcanized is placed on the outer peripheral surface of the unvulcanized rubber for forming the outer peripheral rubber layer 32. Next, a prepreg for forming the first FRP plate 34 having a predetermined length and width is laid over and overlaps half of the outer peripheral surface of the unvulcanized rubber for forming the outer peripheral rubber layer 32 . Next, the ends of unvulcanized rubber for forming the inner rubber layer 24 of a predetermined length and width are aligned with the ends of the gap blocking rubber 38A and placed on the prepreg for forming the first FRP board . Next, the remaining prepreg for forming the first FRP plate 34, which has been overlapped and hung on half of the outer peripheral surface of the unvulcanized rubber for forming the outer peripheral rubber layer 32, is overlapped and hung on the remaining half of the outer peripheral surface of the unvulcanized rubber for forming the outer peripheral rubber layer 32, and is placed on top of the gap blocking rubber 38A and the unvulcanized rubber for forming the internal rubber layer 24.

[0016] Next, the unvulcanized rubber for forming the seal rubber layer 36 is laid over the portion of the prepreg for forming the first FRP board 34 that corresponds to the mounting base 1402 . By vulcanizing and molding in this overlapping state, the unvulcanized rubber for forming peripheral rubber layer 32, the unvulcanized rubber for forming sealing rubber layer 36, and the unvulcanized rubber for forming internal rubber layer 24 are vulcanized to form core material 28, peripheral rubber layer 32, sealing rubber layer 36, and internal rubber layer 24, and the prepreg for forming first FRP plate 34 hardens due to the heat during vulcanization molding to form first FRP plate 34, and the mounting base 1402 for sonar dome 14 is manufactured.

[0017] Next, the remaining method of manufacturing the dome body 18 will be described. First, a piece of unvulcanized rubber for forming the antifouling rubber layer 26 of a predetermined width and length is placed in contact with the end of the sealing rubber layer 36 that constitutes the mounting base 1402 of the sonar dome 14 . Next, the prepreg of the outer FRP plate 22 of a specified width and length is placed on top of the unvulcanized rubber used to form the anti-fouling rubber layer 26, with its end overlapping the end of the first FRP plate 34 that constitutes the mounting base 1402 of the sonar dome 14. Then, the unvulcanized rubber for forming the anti-fouling rubber layer 26 is vulcanized and molded, and the heat generated during vulcanization hardens the prepreg of the outer FRP plate 22 and bonds it to the anti-fouling rubber layer 26, and also bonds it to the end of the first FRP plate 34 that constitutes the mounting base 1402 of the sonar dome 14. Next, unvulcanized rubber for forming the inner rubber layer 24 of a specified width and length is placed on the outer FRP plate 22 with its end in contact with the end of the inner rubber layer 24 that constitutes the mounting base 1402 of the sonar dome 14, and the prepreg of the inner FRP plate 20 of a specified width and length is placed on top of the unvulcanized rubber for forming the inner rubber layer 24 with its end overlapping the end of the first FRP plate 34 that constitutes the mounting base 1402 of the sonar dome 14. The prepreg compositions of the first FRP plate 34, the outer FRP plate 22, and the inner FRP plate 20 are the same. Then, the unvulcanized rubber for forming the inner rubber layer 24 is vulcanized and molded, and the heat generated during vulcanization hardens the prepreg of the inner FRP plate 20 and bonds it to the inner rubber layer 24, and also to the end of the first FRP plate 34 that constitutes the mounting base 1402 of the sonar dome 14. In this manner, the dome bodies 18 are successively manufactured in units of a predetermined length along the extension direction of the bead portion 16 and in units of a predetermined width along the direction perpendicular to the extension direction of the bead portion 16.

[0018] According to the dome body 18 of the sonar dome 14 of the present embodiment, the following actions and effects are achieved. The dome body 18 is configured to include two FRP plates, an inner FRP plate 20 and an outer FRP plate 22, and an inner rubber layer 24 disposed between the two FRP plates. Therefore, if a floating object collides with the dome body 18 while the ship is traveling at high speed, the impact can be absorbed by the internal rubber layer 24, which minimizes damage to the outer FRP plate 22 and is advantageous in protecting the transducer 12 compared to a case in which the dome body 18 is constructed by stacking two FRP plates. In this embodiment, the outer FRP plate 22 is provided with an anti-fouling rubber layer 26 that has anti-fouling and shock absorbing functions, which prevents marine organisms from adhering to the dome body 18 and is advantageous in ensuring the acoustic transparency of the dome body 18. Furthermore, if a floating object collides with the dome body 18 when the ship is traveling at high speed, the impact can also be absorbed by the anti-fouling rubber layer 26, which is advantageous in minimizing damage to the outer FRP plate 22 and protecting the transducer 12.

[0019] In addition, the sonar dome 14 is composed of two FRP plates, an inner FRP plate 20 and an outer FRP plate 22, and an internal rubber layer 24 that is sandwiched between the FRP plates and has a shock absorbing function. Compared to a case in which the dome body 18 is composed of two stacked FRP plates, the sonar dome 14 has higher sound transmittance, making it possible to transmit and receive waves more efficiently, which is advantageous for detecting objects with high accuracy. In addition, the exposure time until the prepreg of an FRP plate hardens is generally short, and the work of uniformly and reliably attaching the prepreg of the FRP plate to the hardened FRP plate over a relatively wide area is difficult to perform. In this embodiment, as described above, vulcanization can be carried out separately for the stain-resistant rubber layer 26 and the inner rubber layer 24.

[0020] In other words, the outer FRP plate 22 can be hardened during vulcanization molding of the anti-fouling rubber layer 26, thereby joining the anti-fouling rubber layer 26 and the outer FRP plate 22, and the inner FRP plate 20 can be hardened during vulcanization molding of the inner rubber layer 24, thereby joining the outer FRP plate 22, the inner rubber layer 24, and the inner FRP plate 20. This is advantageous in shortening the exposure time of the prepregs used to form the outer FRP plate 22 and the prepregs used to form the inner FRP plate 20, and is advantageous in easily and reliably manufacturing the sonar dome 14. Furthermore, even in the case of a dome body 18 that does not have an antifouling rubber layer 26, unvulcanized rubber for forming the inner rubber layer 24 can be placed on top of the prepreg for forming the outer FRP plate 22, and the lower half of the unvulcanized rubber for forming the inner rubber layer 24 in the thickness direction can be vulcanized and molded, thereby hardening the prepreg for forming the outer FRP plate 22 with the heat of vulcanization to form the outer FRP plate 22 and bond it to the inner rubber layer 24, and then the prepreg for forming the inner FRP plate 20 can be placed on top of the upper half of the unvulcanized rubber for forming the inner rubber layer 24 in the thickness direction, and the upper half of the unvulcanized rubber for forming the inner rubber layer 24 in the thickness direction can be vulcanized and molded, thereby hardening the prepreg for forming the inner FRP plate 20 with the heat of vulcanization to form the inner FRP plate 20 and bond it to the inner rubber layer 24. In other words, since the vulcanization can be performed separately for each half of the thickness of the unvulcanized rubber for forming the inner rubber layer 24, this is advantageous in shortening the exposure time of the prepregs for forming the outer FRP plate 22 and the prepregs for forming the inner FRP plate 20, and is advantageous in easily and reliably manufacturing the sonar dome 14.

[0021] Next, a second embodiment will be described with reference to FIG. In the following embodiment, the same parts and members as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted or simplified, with the focus being on the differences. In the second embodiment, the mounting base 1402 and the portion of the dome body 18 adjacent to the mounting base 1402 are different from those in the first embodiment. That is, in the bead portion 16, the second FRP plate 52 is hung on the core material 28 from above the outer peripheral rubber layer 32 inside the first FRP plate 34 and folded back, and the folded second FRP plate 52 is stacked in place of the inner rubber layer 24 at a portion of the dome body 18 near the mounting fixture 48 (mounting base 1402) exposed from the mounting fixture 48 where a large bending moment acts when the ship is traveling at high speed. In detail, the second FRP plate 52 is draped over the outer peripheral rubber layer 32 and the gap blocking rubber 38B and folded back, so that the two second FRP plates 52 are overlapped with each other after passing through the gap blocking rubber 38B and extend to the portion of the dome body 18 near the mounting fixture 48 that protrudes from the mounting fixture 48. The first FRP plate 34 is hung over the second FRP plate 52 at the bead portion 16 and folded back to form the inner FRP plate 20 and the outer FRP plate 22, and the sealing rubber layer 36 is provided to cover the first FRP plate 34 at the mounting base 1402.

[0022] The manufacturing method of sonar dome 14 in the second embodiment differs in that, at the mounting base 1402, the prepreg for forming second FRP plate 52 is hung over the strip of unvulcanized rubber for forming peripheral rubber layer 32, and when it passes through the folded-back gap blocking rubber 38B, the two folded-back prepregs for forming second FRP plate 52 are overlapped, and that the prepreg for forming first FRP plate 34 is hung over the prepreg for forming second FRP plate 52 and folded back. Another difference is that at the portion of the dome body 18 near the mounting base 1402, the inclined end surface is placed on the inclined surface 5202 at the tip of the prepreg used to form the second FRP plate 52, and unvulcanized rubber for forming the inner rubber layer 24 of a specified width and length is placed on the outer FRP plate 22.

[0023] According to the second embodiment, in addition to the same effects as those of the first embodiment, the following effects are achieved. A large bending moment acts on the portion of the dome body 18 near the mounting fixture 48 that is exposed from the mounting fixture 48 when the ship is traveling at high speed. In the second embodiment, a second FRP plate 52 is disposed in place of the inner rubber layer 24 at a location of the dome body 18 near the mounting fixture 48 . This is advantageous in ensuring the strength of the parts of the dome body 18 that are subjected to a large bending moment when the ship is traveling at high speed, and is advantageous in increasing the durability of the sonar dome 14. In addition, the end of the FRP plate formed by stacking the two second FRP plates 52 extending from the mounting base 1402 to the dome main body 18 is formed by an inclined surface 5202 extending in a direction intersecting the direction in which the two second FRP plates 52 are stacked. An end of the two second FRP plates 52 that are stacked together and an end of the inner rubber layer 24 are joined via an inclined surface 5202. Providing such an inclined surface 5202 increases the bonding surface area between the end of the inner rubber layer 24 and the end of the second FRP plate 52, which is advantageous in improving bonding and in improving the strength of the portion of the dome body 18 near the mounting fixture 48.

[0024] Next, a third embodiment will be described with reference to FIG. The third embodiment is obtained by adding a third FRP plate 54 to the second embodiment. That is, the third FRP plate 54 is hung from above the first FRP plate 34 at the bead portion 16 onto the core material 28 and folded back, and the two third FRP plates 54 are each positioned at a portion of the dome body 18 near the mounting fixture 48 and protruding from the mounting fixture 48, and the sealing rubber layer 36 is provided so as to cover the third FRP plate 54 at the mounting base 1402. The third FRP plate 54 is arranged at a portion of the dome body 18 near the mounting fixture 48 and exposed from the mounting fixture 48, and is arranged so that the thickness of the surface of the inner FRP plate 20 facing the transducer 12 and the surface of the outer FRP plate 22 facing away from the transducer 12 decreases stepwise as the distance from the mounting fixture 48 increases. In this embodiment, the portion closest to the mounting portion 1402 is formed as the first plate portion 54A, which is the thickest, followed by the second plate portion 54B, which is thinner than the first plate portion 54A, and then the third plate portion 54C, which is thinner than the second plate portion 54B.

[0025] The manufacturing method of the sonar dome 14 in the third embodiment differs from that in the second embodiment in that, at the mounting base 1402 and the portion of the dome body 18 in its vicinity, the prepreg for forming the third FRP plate 54 is draped over the prepreg for forming the first FRP plate 34 and folded back, and then unvulcanized rubber for forming the sealing rubber layer 36 is placed on top of that; the prepreg for forming the third FRP plate 54 protruding from the mounting base 1402 is placed on top of the unvulcanized rubber for forming the anti-fouling rubber layer 26, and then the prepreg for forming the outer FRP plate 22 is placed on top of that; and the prepreg for forming the third FRP plate 54 protruding from the mounting base 1402 is placed on top of the prepreg for forming the inner FRP plate 20.

[0026] According to the third embodiment, in addition to the same effects as those of the first embodiment, the following effects are achieved. A large bending moment acts on the portion of the dome body 18 near the mounting fixture 48 that is exposed from the mounting fixture 48 when the ship is traveling at high speed. In the third embodiment, a third FRP plate 54 is arranged on the surface of the inner FRP plate 20 facing the transducer 12 and on the surface of the outer FRP plate 22 facing away from the transducer 12 at the portion of the dome body 18 near the transducer 48 that is exposed from the transducer 48. Furthermore, the second FRP plate 52 is also disposed at a portion of the dome body 18 near the mounting fixture 48 and exposed from the mounting fixture 48 . This is advantageous in ensuring the strength of the parts of the dome body 18 that are subjected to a large bending moment when the ship is traveling at high speed, and is further advantageous in increasing the durability of the sonar dome 14. In addition, the third FRP plate 54, which is arranged on the portion of the dome body 18 near the mounting fixture 48 and exposed from the mounting fixture 48, is arranged so that its thickness gradually decreases with increasing distance from the mounting base 1402 on the surface of the inner FRP plate 20 facing the transducer 12 and on the surface of the outer FRP plate 22 facing away from the transducer 12, in response to the stress distribution that occurs when the ship is traveling at high speed. This is advantageous in ensuring the strength of the parts of the dome body 18 that are subjected to a large bending moment when the ship is traveling at high speeds, and at the same time, it is possible to suppress the occurrence of stress concentration, which is more advantageous in increasing the durability of the sonar dome 14. [Explanation of symbols]

[0027] 10. Bottom of the Ship 12 Transmitter / Receiver 14 Sonar Dome 1402 Mounting base 16 Bead section 18 Dome body 20 Inner FRP plate 22 Outside FRP board 24 Inner rubber layer 26 Antifouling rubber layer 28 Core material 32 Outer rubber layer 34 1st FRP board manufacturing 36 Sealing rubber layer 38A, 38B Gap-blocking rubber 42 Mounting material 44 Bead seat 4402 Bead seat side mating surface 4404 Bead seat side clamping surface 46 Bead clamp 4602 Bead clamp side mating surface 4604 Bead clamp side clamping surface 48 Mounting fixtures 52 2nd FRP plate 5202 Slope 54 No. 3 FRP board manufacturing 54A First Plate 54B 2nd plate part 54C 3rd plate part

Claims

1. A sonar dome comprising a bead portion attached to a bottom side of a vessel, and a dome body extending from the bead portion and covering a transducer installed on the bottom of the vessel, the dome body is configured to include an inner FRP plate forming a portion of the dome body located on the transducer side, an outer FRP plate forming a portion of the dome body located opposite the transducer, and an inner rubber layer having a shock absorbing function that is disposed between the inner FRP plate and the outer FRP plate; The bead portion is configured to include a core material, A first FRP plate is hung on the core material at the bead portion and folded back, The inner FRP plate and the outer FRP plate are formed by the folded first FRP plate. A sonar dome that features

2. The bead portion and a portion of the dome body in the vicinity of the bead portion serve as a mounting base supported by a mounting fixture on the bottom side of the vessel, A second FRP plate is hung on the core material and folded back on the inner side of the first FRP plate in the bead portion, The portion of the dome body exposed from the mounting fixture that is closer to the mounting fixture is overlapped with the folded second FRP plate, and is disposed in place of the inner rubber layer.

2. The sonar dome of claim 1.

3. The dome body further includes an antifouling rubber layer attached to a surface of the outer FRP plate facing away from the transducer and having an antifouling function and a shock absorbing function.

3. The sonar dome according to claim 1 or 2.

4. In the bead portion, a third FRP plate is hung on the core material and folded back on the outer side of the first FRP plate, At a portion of the dome body exposed from the mounting fixture and closer to the mounting fixture, the folded third FRP plate is disposed on a surface of the inner FRP plate facing the transducer side and a surface of the outer FRP plate facing away from the transducer.

3. The sonar dome according to claim 2.

5. The dome body further includes an antifouling rubber layer having an antifouling function and an impact absorbing function, The antifouling rubber layer is attached to a surface of the third FRP plate facing away from the transducer at a portion of the dome body closer to the mounting fixture, and is attached to a surface of the outer FRP plate facing away from the transducer at the remaining portions of the dome body excluding the portion closer to the mounting fixture.

5. The sonar dome according to claim 4.

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