Medium-high-speed double-paddle ship
By designing the bulging structure and optimizing the shaft support at the stern of the medium and high-speed double-suspension boat, the problems of large resistance, low propeller efficiency and insufficient space are solved, the propulsion efficiency and cavitation performance are improved, the excitation force is reduced, and the vibration force is achieved is achieved better Comfort.
Patent Information
- Application Number
- CN202411564275.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-05
- Publication Date
- 2024-12-27
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The existing tail propulsion structure of medium and high-speed double-propeller boats has problems such as high resistance, low propeller efficiency, insufficient space and high risk of propeller cavitation.
A medium-high speed double-propelled boat is designed, with a symmetrical bulge structure at the stern to accommodate the gearbox, and the propulsion shaft and shaft support components are used to connect and drive the propeller, which shortens the propulsion shaft length and reduces the tail companion flow, and By optimizing the design of the shaft bracket and water splitter, the resistance and propeller excitation force are reduced.
It improves propulsion efficiency, improves propeller cavitation performance, reduces propeller vibration force affected by the hull, reduces resistance, increases internal space, and provides better comfort.
Smart Images
Figure CN119190253A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of ships, and in particular to a medium- and high-speed twin-propeller ship. Background Art
[0002] Medium- and high-speed ships generally refer to ships with a Froude number greater than 0.2. In order to achieve their fast performance, the ship type is generally slender, that is, the ship type length-to-width ratio is relatively large, generally greater than 5.5, and the square coefficient is relatively small, generally less than 0.7. According to the difference in square coefficient and width-to-draft ratio, the stern design is divided into single-propeller and double-propeller. Double-propeller ships are often used in passenger ro-ro ships, passenger ships and steam ro-ro ships. This type of ship type has a relatively large width and draft, which limits the propeller diameter, and the square coefficient is also small, and the stern is thinner.
[0003] At present, there are usually two forms of support for the propulsion structure at the tail of medium- and high-speed twin-propeller ships: a double tail fin form and a shaft bracket form. The first double tail fin form uses the form of adding a tail fin to the bulge of the hull to wrap the propulsion structure, leaving only the propeller extending and pushing the ship. This form can produce pre-rotation on the propeller and improve the propulsion efficiency of the propeller, but the setting of the tail fin increases the hull resistance and the stern wake, thereby increasing the risk of propeller cavitation. The propeller exciting force (also known as pulsating pressure) on the hull will also increase, thereby increasing the risk of hull vibration and increased noise. The second type of shaft bracket has a smooth light body at the tail, and the propulsion shaft extends from the hull to the propeller disk. Several shaft brackets will be arranged at the tail to support the propulsion shaft. Generally, there will be two in sequence, one I-shaped and one V-shaped. This type of tail design has better resistance performance, and the tail wake is usually smaller, which is more beneficial to the propeller cavitation performance; however, this form is not very beneficial to the propeller propulsion performance, and the propeller efficiency is generally lower than 0.7. At the same time, due to the longer shaft support at the tail and the thinner tail line, the gearbox and main engine are often arranged relatively forward, which compresses the space of the cabin and cargo hold, causing the problem of insufficient space.
[0004] In addition, existing medium- and high-speed twin-propeller ships are usually equipped with a watershed amidships, which can stabilize the course, but it extends from the bow to the stern, has a large volume, increases the hull resistance, and thus increases the propulsion power of the ship.
[0005] Therefore, a medium-high speed double-screw boat is urgently needed to solve the above-mentioned technical problems. Summary of the invention
[0006] The object of the present invention is to provide a medium-to-high-speed twin-propeller ship, which can reduce resistance, improve propulsion efficiency, and at the same time has a better wake, which helps to improve the propeller cavitation performance and reduce the pulsating pressure generated by the propeller on the hull.
[0007] To achieve this object, the present invention adopts the following technical solutions:
[0008] Medium and high speed double propeller boat, including:
[0009] A hull, wherein the bottom of the stern of the hull is provided with two bulges symmetrically arranged along the central axis in the width direction of the hull;
[0010] Two propulsion devices, the two propulsion devices are symmetrically arranged along the central axis of the width direction of the hull and are arranged one-to-one in the two bulges, the propulsion devices include a main engine, a gear box, a propulsion shaft and a propeller, the main engine is arranged in the hull, the gear box is arranged in the bulge and connected to the main engine, one end of the propulsion shaft is connected to the gear box, and the other end is passed through the bulge and connected to the propeller;
[0011] Each of the propulsion shafts is provided with a shaft support assembly, one end of the shaft support assembly is connected to the propulsion shaft, and the other end is connected to the hull to support the propulsion shaft.
[0012] Optionally, the distance between the bulge and the central axis in the width direction of the hull gradually decreases from the bow to the stern of the hull.
[0013] Optionally, the shaft support assembly comprises a front end bracket, a first shaft bracket and a shaft support member, and in a direction from the gear box to the propeller, the front end bracket, the first shaft bracket and the shaft support member are sequentially arranged on the propulsion shaft;
[0014] The above-mentioned front end bracket is arranged on the side of the above-mentioned propulsion shaft close to the above-mentioned bulge and is connected to the above-mentioned hull; the above-mentioned first shaft bracket is connected to the above-mentioned hull; the above-mentioned shaft support member includes a second shaft bracket and a third shaft bracket, the above-mentioned second shaft bracket and the above-mentioned third shaft bracket are arranged at an angle, the above-mentioned second shaft bracket is arranged in the same direction as the above-mentioned first shaft bracket and is connected to the above-mentioned hull, and the above-mentioned third shaft bracket is connected to the watershed midship of the above-mentioned hull.
[0015] Optionally, the angle between the second axis support and the third axis support is A, 80°≤A≤100°.
[0016] Optionally, the first shaft bracket, the second shaft bracket and the third shaft bracket are all tilted toward the bow of the hull.
[0017] Optionally, the inclination angle of the first axis support is α, 0°≤α≤6°; the inclination angle of the second axis support is β, 0°≤β≤5°; the inclination angle of the third axis support is γ, 0°≤γ≤7°.
[0018] Optionally, the propulsion shaft is provided with a shaft sleeve, the front end bracket, the first shaft bracket and the shaft support are all connected to the shaft sleeve, and the first shaft bracket, the second shaft bracket and the third shaft bracket are all arranged tangent to the shaft sleeve.
[0019] Optionally, the length between perpendicular lines of the hull is L, the axial length of the propulsion shaft is A, and 0.05L≤A≤0.1L.
[0020] Optionally, a watershed is further provided at the bottom of the stern of the hull, and the two propulsion devices are respectively arranged on both sides of the watershed.
[0021] Optionally, the length of the watershed midship is not greater than the length of the propulsion shaft.
[0022] Beneficial effects of the present invention:
[0023] The present invention provides a medium-high speed twin-propeller ship, a partial bulge structure is added to the stern of the ship to accommodate a gearbox, so that the propulsion device does not need to squeeze the internal space forward when it is arranged, which solves the problem of insufficient space when the propulsion device is arranged in the form of a central axis bracket in the prior art; and the bulge is only used to accommodate the gearbox, and its size is small, which reduces the hull resistance, improves the hull resistance and propeller cavitation risk when the propulsion device is arranged in the form of a double tail fin, and improves the propulsion efficiency. In addition, the connection and drive with the propeller are achieved through the propulsion shaft and the shaft support assembly outside the bulge. Since the propulsion devices are all rear-mounted, the length of the propulsion shaft is shortened, the tail wake is reduced, which is conducive to improving the efficiency of the propeller, and improves the cavitation of the propeller, and reduces the propeller exciting force on the hull. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is an axonometric view of a partial structure of the stern of a medium- and high-speed twin-propeller ship provided in a specific embodiment of the present invention;
[0025] Figure 2 It is a front view of a partial structure of the stern of a medium- and high-speed double-propeller ship provided by a specific embodiment of the present invention;
[0026] Figure 3 It is a cross-sectional view of the stern of a medium- and high-speed double-propeller ship provided by a specific embodiment of the present invention;
[0027] Figure 4 is a side view of the installation of the first shaft support provided by a specific embodiment of the present invention;
[0028] Figure 5 is a side view of the installation of the shaft support provided by the specific embodiment of the present invention;
[0029] Figure 6 yes Figure 2 A partial enlarged view of the middle A;
[0030] Figure 7 yes Figure 2 A partial enlarged view of point B in the middle.
[0031] In the figure:
[0032] 0, 1, 2...6 represent the station number;
[0033] CL, centerline of hull;
[0034] BL, baseline of the hull;
[0035] 10. Hull; 11. Stern; 12. Drum; 13. Watershed midship;
[0036] 21. Propulsion shaft; 22. Propeller; 23. Rudder blade;
[0037] 30. Shaft support assembly; 31. Front end bracket; 32. First shaft bracket; 33. Shaft support; 331. Second shaft bracket; 332. Third shaft bracket. DETAILED DESCRIPTION
[0038] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.
[0039] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0040] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.
[0041] In the description of this embodiment, the terms "upper", "lower", "left", "right", etc., and the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplified operation, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.
[0042] Refer to the following Figures 1 to 7 The invention discloses a medium-high speed double-propeller boat.
[0043] It should be noted that the medium-high speed twin-propeller ship divides the hull 10 into N equally spaced stations along the length direction of the ship, and the spacing is called the station spacing. Generally, the station numbers are divided into 0, 1, 2, 3 ... N from the stern 11 to the bow.
[0044] Please refer to Figure 1 and Figure 2 The present embodiment provides a medium-high speed double-screw boat, which includes a hull 10, two propulsion devices and two shaft support assemblies 30. The bottom of the stern 11 of the hull 10 is provided with two bulges 12 symmetrically arranged along the central axis of the width direction of the hull 10; the two propulsion devices are symmetrically arranged along the central axis of the width direction of the hull 10 and are arranged one-to-one with the two bulges 12, the propulsion device includes a main engine, a gearbox, a propulsion shaft 21 and a propeller 22, the main engine is arranged in the hull 10, the gearbox is arranged in the bulge 12 and connected to the main engine, one end of the propulsion shaft 21 is connected to the gearbox, and the other end is passed through the bulge 12 and connected to the propeller 22; each propulsion shaft 21 is provided with a shaft support assembly 30, one end of the shaft support assembly 30 is connected to the propulsion shaft 21, and the other end is connected to the hull 10 to support the propulsion shaft 21.
[0045] The medium-high speed twin-propeller boat in this embodiment has a partial bulge 12 structure added to its stern 11 to accommodate the gearbox, so that the propulsion device does not need to squeeze the internal space forward when it is arranged, which solves the problem of insufficient space when the propulsion device is arranged in the form of a central axis bracket in the prior art; and the bulge 12 is only used to accommodate the gearbox, and its size is small, which reduces the resistance of the hull 10, improves the larger problems such as the resistance of the hull 10 and the cavitation risk of the propeller 22 when the propulsion device is arranged in the form of a double tail fin, and improves the propulsion efficiency. In addition, the connection and drive with the propeller 22 are realized by the propulsion shaft 21 and the shaft support assembly 30 outside the bulge 12. Since the propulsion devices are all rear-mounted, the length of the propulsion shaft 21 is shortened, and the tail wake is reduced, which is conducive to improving the efficiency of the propeller 22, and improving the cavitation of the propeller 22, and reducing the exciting force of the propeller 22 on the hull 10.
[0046] Please refer to Figure 3Specifically, the bulge 12 extends from station 2 to near station 6, and a propulsion shaft 21 and a propeller 22 are provided between station 0 and station 2, that is, the stern 11 does not completely wrap the propulsion device in the hull 10, which reduces the volume of the bulge 12 and thus reduces the resistance of the hull 10.
[0047] Optionally, the distance between the bulge 12 and the central axis of the width direction of the hull 10 gradually decreases from the bow to the stern 11 of the hull 10. This arrangement satisfies the flow field trend of the hull 10, facilitates the streamline to flow smoothly from the bottom and side of the ship to the propeller 22, helps to reduce the resistance of the hull 10, stabilizes the flow in front of the propeller, and also helps to improve the efficiency of the propeller 22, improve the cavitation of the propeller 22, and reduce the excitation force of the propeller 22 on the hull 10. For details, please refer to Figure 3 The dotted line in the middle of the figure is the line connecting the lowest points of each station of the bulge 12. It can be clearly seen that from station 2 to station 6, the lowest point of the bulge 12 gradually extends toward the side of the ship, which means that when the bulge 12 extends from the bow to the stern 11, it extends from the outside toward the central axis of the width direction of the hull 10, that is, the distance between the bulge 12 and the central axis of the width direction of the hull 10 gradually decreases.
[0048] Please refer to Figure 2 , Figure 4 and Figure 5 Specifically, the propulsion shaft 21 extends horizontally from the bulge 12 to the position of the propeller 22. Optionally, the propulsion shaft 21 is further provided with a shaft sleeve to protect the propulsion shaft 21.
[0049] Optionally, the length between perpendicular lines of the hull 10 is L, the axial length of the propulsion shaft 21 is E, and 0.05L≤E≤0.1L, so that the reference size of the shortened propulsion shaft 21 can be obtained.
[0050] Optionally, the design draft of the medium-high speed twin-propeller ship is T, the axis height of the propulsion shaft 21 is F, 0.3T≤F≤0.5T, which can meet the position of the propulsion shaft 21 and the connection between the propulsion shaft 21, the propeller 22 and the gear box. It can be understood that the axis height of the propulsion shaft 21 is the distance between the axis of the propulsion shaft 21 and the baseline BL of the hull 10.
[0051] Optionally, the width of the hull 10 of the medium- and high-speed twin-propeller ship is B, the distance between the axis of the propulsion shaft 21 and the center line CL of the hull 10 is G, and 0.1B≤G≤0.3B can satisfy the position of the propulsion shaft 21 and the connection between the propulsion shaft 21 and the propeller 22 and the gearbox.
[0052] Please refer to Figure 2 , Figure 6 and Figure 7In this embodiment, the shaft support assembly 30 includes a front bracket 31, a first shaft bracket 32 and a shaft support member 33. In the direction from the gearbox to the propeller 22, the front bracket 31, the first shaft bracket 32 and the shaft support member 33 are sequentially arranged on the propulsion shaft 21; the front bracket 31 is arranged on the side of the propulsion shaft 21 close to the bulge 12 and connected to the hull 10. The first shaft bracket 32 is connected to the hull 10. The shaft support member 33 includes a second shaft bracket 331 and a third shaft bracket 332. The second shaft bracket 331 and the third shaft bracket 332 are arranged at an angle. The second shaft bracket 331 is arranged in the same direction as the first shaft bracket 32 and connected to the hull 10, and the third shaft bracket 332 is connected to the watershed 13 of the hull 10. The front bracket 31, the first shaft bracket 32 and the shaft support member 33 support the propulsion shaft 21, and the stability of the connection between the propulsion shaft 21 and the hull 10 is improved. The second shaft bracket 331 and the first shaft bracket 32 are extended in the same direction, and the second shaft bracket 331 is connected to the watershed midship 13 to form an L-shape, which greatly shortens the length of the two shaft brackets and avoids the increase in the length of the shaft brackets when the two shaft brackets are connected to the hull 10 in a V-shape.
[0053] Specifically, the front end bracket 31 is arranged on the side of the propulsion shaft 21 close to the bulge 12 to fix and support the front end of the propulsion shaft 21; the first shaft bracket 32 is arranged on the propulsion shaft 21 near the middle along its own length direction, which can support the middle part of the propulsion shaft 21; the shaft support 33 is arranged on the side of the propulsion shaft 21 close to the propeller 22 to fix and support the rear end of the propulsion shaft 21.
[0054] More specifically, the first shaft bracket 32 extends from the propulsion shaft 21 to the nearest position of the hull 10, which is a relatively flat position near the middle of the hull 10 along its own width direction and is the lowest position of the hull 10. The first shaft bracket 32 extends from the propulsion shaft 21 to the nearest position of the hull 10, which reduces the length of the first shaft bracket 32 and also ensures its fixing effect.
[0055] More specifically, the second shaft bracket 331 and the first shaft bracket 32 extend in the same direction, so the second shaft bracket 331 also reduces its own length, and because the propulsion shaft 21 is close to the propeller 22, its exciting force is relatively large, so two shaft brackets are provided here, which can better achieve the fixing and supporting function of the propulsion shaft 21. The second shaft bracket 331 and the first shaft bracket 32 extend in the same direction, and the second shaft bracket 331 is connected to the watershed midship 13, and it also extends from the propulsion shaft 21 to the nearest position of the watershed midship 13, which greatly shortens the length of the two shaft brackets and avoids the increase of the length of the shaft brackets when the two shaft brackets are connected to the hull 10 in a V shape.
[0056] Optionally, the propulsion shaft 21 is provided with a shaft sleeve, and the front end bracket 31, the first shaft bracket 32 and the shaft support 33 are all connected to the shaft sleeve, and the first shaft bracket 32, the second shaft bracket 331 and the third shaft bracket 332 are all arranged tangent to the shaft sleeve, so that the first shaft bracket 32, the second shaft bracket 331 and the third shaft bracket 332 are respectively connected to the corresponding hull 10 or the propulsion shaft 21 at the shortest distance, which not only meets the support and fixation of the propulsion shaft 21, but also reduces the structural volume.
[0057] Optionally, the angle between the second shaft support 331 and the third shaft support 332 is θ, 80°≤θ≤100°, that is, the second shaft support 331 and the third shaft support 332 are approximately L-shaped, which shortens the length of the two shaft supports and also meets the streamline requirements.
[0058] In some embodiments, the cross-sections of the first shaft bracket 32, the second shaft bracket 331 and the third shaft bracket 332 all adopt NACA airfoils, which have low resistance characteristics and avoid affecting the propulsion efficiency and cavitation performance of the medium- and high-speed twin-propeller ship.
[0059] Specifically, the first shaft bracket 32, the second shaft bracket 331 and the third shaft bracket 332 are all tilted toward the bow of the hull 10 to meet the streamline changes at this position, thereby achieving acceleration and pre-spin of the propeller 22 flow, thereby improving the efficiency of the propeller 22, reducing the risk of harmful cavitation of the propeller 22, and reducing the exciting force of the propeller 22.
[0060] More specifically, the first shaft support 32 has an inclination angle of α, 0°≤α≤6°; the second shaft support 331 has an inclination angle of β, 0°≤β≤5°; the third shaft support 332 has an inclination angle of γ, 0°≤γ≤7°. They can all meet the change of the water flow streamline, thereby realizing the acceleration and pre-spin of the propeller 22 flow, thereby improving the efficiency of the propeller 22, reducing the risk of harmful cavitation of the propeller 22, and reducing the exciting force of the propeller 22.
[0061] In some embodiments, the propulsion device further includes a rudder blade 23, which is disposed at the bottom of the stern 11 of the hull 10 and at a side of the propeller 22 away from the propulsion shaft 21, and the rudder blade 23 is used to control the heading of the ship.
[0062] Please refer to Figure 1 and Figure 2 In this embodiment, a watershed 13 is further provided at the bottom of the stern 11 of the hull 10, and two propulsion devices are respectively arranged on both sides of the watershed 13. The watershed 13 is only arranged at the stern 11 and does not extend to the middle of the ship and the bow, so that its volume is reduced, thereby also reducing the wet surface area of the watershed 13, thereby reducing the resistance of the hull 10, and the watershed 13 can also play a role in improving the heading stability.
[0063] Specifically, the length of the watershed midship 13 is not greater than the length of the propulsion shaft 21 . This arrangement can ensure that it can meet the function of improving the heading stability while also greatly reducing the volume, further reducing the resistance of the hull 10 .
[0064] Optionally, the watershed midship 13 is divided into an upper end and a lower end, the upper end is arranged in the hull 10, and the lower end is arranged between the two propulsion devices. Optionally, the length between perpendicular lines of the hull 10 is L, the distance between the lower end of the watershed midship 13 and the baseline BL of the hull 10 is H1, H1=0.15m; the length of the lower end of the watershed midship 13 is L1, 0.05L≤L1≤0.15L; the thickness of the lower end of the watershed midship 13 is T1, 0.1m≤T1≤0.6m; the distance between the upper end of the watershed midship 13 and the baseline BL of the hull 10 is H2, 1T≤H2≤1.3T; the length of the upper end of the watershed midship 13 is L2, 0.05L≤L2≤0.15L; the thickness of the upper end of the watershed midship 13 is T2, 0.5m≤T2≤1m; such an arrangement makes its thickness meet the structural strength requirements and also meet the design requirements of the dock pier.
[0065] It can be understood that the medium-high speed twin-propeller boat in this embodiment reduces the resistance by 6% compared with the medium-high speed twin-propeller boat in the form of an axle bracket and the medium-high speed twin-propeller boat in the form of a double tail fin in the prior art; and reduces the resistance by 3% compared with the medium-high speed twin-propeller boat in the form of an original axle bracket and a long watershed 13. At the same time, it can also improve the propulsion efficiency by 2%. Finally, the efficiency of the propeller 22 reaches 0.72, and the cavitation performance of the propeller 22 is good, the cavitation on the propeller surface is stable, and the exciting force is very low, which is only 1.2 kPa for the first order, 0.3 kPa for the second order, and 0.2 kPa for the third order, so that the medium-high speed twin-propeller boat can provide excellent comfort for crew members and passengers.
[0066] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.
Claims
1. Medium-high speed double-screw boat, characterized in that: include: A hull (10), wherein the bottom of the stern (11) of the hull (10) is provided with two bulges (12) symmetrically arranged along the central axis in the width direction of the hull (10); Two propulsion devices, the two propulsion devices are symmetrically arranged along the central axis of the width direction of the hull (10) and are arranged one-to-one with the two bulges (12), the propulsion devices include a main engine, a gear box, a propulsion shaft (21) and a propeller (22), the main engine is arranged in the hull (10), the gear box is arranged in the bulge (12) and is connected to the main engine, one end of the propulsion shaft (21) is connected to the gear box, and the other end is passed through the bulge (12) and is connected to the propeller (22); Each of the propulsion shafts (21) is provided with a shaft support assembly (30), one end of the shaft support assembly (30) is connected to the propulsion shaft (21), and the other end is connected to the hull (10) to support the propulsion shaft (21).
2. The medium-high speed double-propeller boat according to claim 1, characterized in that: From the bow to the stern (11) of the hull (10), the distance between the bulge (12) and the central axis of the width direction of the hull (10) gradually decreases.
3. The medium-high speed double-propeller boat according to claim 1, characterized in that: The shaft support assembly (30) comprises a front end bracket (31), a first shaft bracket (32) and a shaft support member (33), and in a direction from the gear box to the propeller (22), the front end bracket (31), the first shaft bracket (32) and the shaft support member (33) are sequentially arranged on the propulsion shaft (21); The front end bracket (31) is arranged on a side of the propulsion shaft (21) close to the bulge (12) and is connected to the hull (10); the first shaft bracket (32) is connected to the hull (10); the shaft support member (33) includes a second shaft bracket (331) and a third shaft bracket (332), the second shaft bracket (331) and the third shaft bracket (332) are arranged at an angle, the second shaft bracket (331) and the first shaft bracket (32) are arranged in the same direction and are connected to the hull (10), and the third shaft bracket (332) is connected to the watershed midship (13) of the hull (10).
4. The medium-high speed double-propeller boat according to claim 3, characterized in that: The included angle between the second axis support (331) and the third axis support (332) is A, 80°≤A≤100°.
5. The medium-high speed double-propeller boat according to claim 3, characterized in that: The first shaft support (32), the second shaft support (331) and the third shaft support (332) are all arranged to be inclined toward the bow of the hull (10).
6. The medium-high speed double-propeller boat according to claim 5, characterized in that: The inclination angle of the first shaft support (32) is α, 0°≤α≤6°; the inclination angle of the second shaft support (331) is β, 0°≤β≤5°; and the inclination angle of the third shaft support (332) is γ, 0°≤γ≤7°.
7. The medium-high speed double-propeller boat according to claim 3, characterized in that: The propulsion shaft (21) is provided with a shaft sleeve, the front end bracket (31), the first shaft bracket (32) and the shaft support (33) are all connected to the shaft sleeve, and the first shaft bracket (32), the second shaft bracket (331) and the third shaft bracket (332) are all arranged tangentially to the shaft sleeve.
8. The medium-high speed double-propeller boat according to claim 1, characterized in that: The length between perpendicular lines of the hull (10) is L, the axial length of the propulsion shaft (21) is A, and 0.05L≤A≤0.1L.
9. The medium-high speed double-propeller boat according to any one of claims 1 to 8, characterized in that: A watershed (13) is also provided at the bottom of the stern (11) of the hull (10), and the two propulsion devices are respectively arranged on both sides of the watershed (13).
10. The medium-high speed double-propeller boat according to claim 9, characterized in that: The length of the watershed midship (13) is not greater than the length of the propulsion shaft (21).