Jet propulsion small boat

Abstract: The invention relates to a jet propulsion small boat comprising a deck member (3) and a hull member (2), both integrally formed from synthetic resin such as FRP and bonded with each other at their fringe portions. The deck member has bulwarks (8) formed at its fringe portions except at its stern end, a seat stand (5) and an operating handle stand (6) projectingly formed on the hull centre line and the decks (30, 33) formed on both sides of these stands, said bulwarks have buoyancy spaces (80) formed within themselves to function as floats and the sizes of said buoyancy spaces are set up such that the hull centre line may take its position above a draft plane (91) when the boat hull is rolled sideways by 90°.

Description: The present invention relates to a jet propulsion boat, as indicated in the introductory portion of the main claim, which runs on the sea surface at a high speed with one or a plurality of riders on it, enabling also to make use of the boat for other activities such as fishing, leaving the boat drifting on the sea surface. Known from practical use are jet propulsion boats (US-A-4744325) which are engined small boats for gliding on the water surface like a motor-cycle type jet propulsion boat. Since such a jet propulsion boat is used for practising various motions such as slaloming, jumping, tricking, etc, while gliding at high speed on the water surface, driven by the power of the engine aboard, it is provided with seats including, for example, a bench seat on the hull centre line, and an operating handle bar stand on its front portion. The boat is operated by a rider sitting astride the seat with his feet placed on the decks on either side. As the aforementioned jet propulsion boat practises various motions such as rapid turns while gliding on the water surface at high speed, it suffers a large inclining moment and will often be overturned. Accordingly, its boat hull requires a large righting moment while being constructed compactly to obtain an excellent movability. Moreover, an air intake opening for the engine should be provided in such a manner that water will never enter the engine room, even when the boat rolls sideways. However, prior art structures of a boat hull construction having a larger righting moment generally need a wider boat hull and, accordingly, imply poorer movability. Moreover, it has turned out to be difficult to prevent water from coming in the boat when it rolls sideways while simultaneously exhibiting a good ventilating function to ventilate the engine room. The present invention has been made to solve such existing problems as mentioned above and, accordingly, it is an object of the present invention to provide a jet propulsion small boat having excellent movability due to its compact structure, establishing a large righting moment sufficient for stable gliding and, moreover, to design the boat such that water is prevented from coming into the engine room of the boat even when it rolls sideways. In accordance with the present invention, the aforementioned object is achieved through a jet propulsion small boat comprising a deck member and a hull member both integrally formed from synthetic resin such as FRP and bonded with each other at their fringe portions. In particular, the present invention is characterized in that said deck member comprises bulwarks formed at its fringe portions except at its stern end, a seat stand and an operating handle bar stand projectingly formed on the hull centre line, decks formed at least on both sides of these stands, said bulwarks defining buoyancy spaces formed within said bulwarks to function as floats, with the size of said buoyancy spaces being set up such that the hull centre line of the boat may take its position above the water line when the boat hull is rolled sideways by approximately 90° and ventilation pipes 4a, 4b are provided, substantially aligned on the hull centre line 10. In order to increase the buoyancy of the boat, said buoyancy spaces advantageously form hermetically sealed spaces. According to an advantageous embodiment of the present invention, said buoyancy spaces are separated from the remainder displacement volume of the boat defined in between the deck member and the bottom plate of the hull member by preferably inclined side walls extending longitudinally inside the hollow internal space or displacement volume of the boat. The effects of said side walls could be enhanced with said side walls set inclining inwardly. Advantageously, said buoyancy spaces alternatively are filled with air or foam plastics which form floats in order to increase the stability of the boat. Moreover, the height of the bulwarks could preferably correspond approximately to the height of the seat stand, thus forming channel-like deck portions at both sides of the stand extending longitudinally along the boat and being open along the rear stern portion thereof to allow water thrown up on the boat to be substantially unrestrictedly exhausted. According to another advantageous embodiment of the present invention and in order to increase the convenience of the users of the boat, the rear end portions of the decks preferably form integral footings having a forward inclination to allow the rider to keep his feet against them when sitting astride a seat or bench seat provided on the seat stand. In order to allow water to flow off the decks, each of said footings has steps on both sides formed by cutting off portions of its width and a substantially L-shaped support plate being attached along these steps in order to support a flap made of a flexible material such as rubber. Preferably, said flap is attached to a support plate through bolts setting the flap to close an opening formed beneath the support plate and keeping said resilient flap substantially vertical. Said opening is formed in the assembled state of the respective footing with the support plate attached thereto. Both end portions of the flap are supported by the rear portions of the steps in order to avoid the flap being bent forwardly but allowing the flap to be bent rearwardly, respectively. Thus, water thrown up on board can flow off the stern ends of the decks, irrespective of said footings associated to both decks beside the seat stand even though water is prevented from entering the decks from the rear due to the flaps associated to the footings, respectively. According to another advantageous embodiment of the invention preventing water from coming into the engine room of the boat even when the boat is overturned by approximately 180°, ventilation pipes are provided, substantially aligned on the hull centre line or hull centre plane, respectively, with their upper ends opened above the seat stand and with their lower ends opened above the draft plane of the boat hull when overturned by approximately 180°. Said ventilation pipes open with their lower ends into the engine room of the boat beneath the seat stand in such a manner that they are positioned above the draft plane in any inclined states of the boat and water is reliably prevented from coming into the engine room even though the upper end portions of said ventilation pipes could be prone to be positioned below said draft plane. Accordingly, an engine room is advantageously provided beneath the operating handle stand and the seat stand adapted to receive at least an engine and a fuel tank, adapted to receive at least an engine and a fuel tank, with the lower ends of the ventilation pipes opening into the engine room in such a manner to be positioned at a height that their mouth portions reliably open above the draft plane of the boat hull irrespective of the inclination of same, in particular when the boat hull is overturned by approximately 180°. It is preferred that fresh air is taken into the engine room through the front ventilation pipe and the air inside the engine room is exhausted through the rear ventilation pipe. Moreover, in order to provide appropriate air circulation, ventilation hoses for the fuel tank and ventilation hoses for a battery are also connected to the ventilation pipes near the lower end portions thereof, respectively. The assembly of the ventilation pipes is preferably performed such that the upper end of the front ventilation pipe penetrates the seat stand in front of the operating handle stand to open into a space behind the front seat of the boat which is communicated with the atmosphere through channels formed by the rim portions of the front seat in conjunction with the supporting seat stand, while the upper end of the rear ventilation pipe penetrates the seat stand behind the operating handle stand to open into a space beneath the rear seat of the boat, said space being communicated to the atmosphere through channels formed by the rim portions of the rim seat in conjunction with the supporting seat stand. With the above-mentioned structure of a jet propulsion small boat according to the present invention, water can be prevented from coming into the boat and can in particular be prevented from entering the engine room thereof, while the boat exhibits an excellent stability for various motions while gliding. Said capabilities result from the design of buoyancy spaces which are provided with large buoyancy and which are formed by bulwarks formed at the fringes of the boat hull, composed of the hull member and the deck member in order to bring the hull centre line into its position above the draft plane when the boat is rolled sideways. Thus, the entrance of water can be reliably prevented. Especially due to the installation of ventilation pipes on the hull centre line with their lower ends at a depth above the draft plane, water can be prevented from coming in even when the boat is overturned by 180°. Further objects, features and objectives of the present invention are highlighted in the following description explaining an embodiment of a jet propulsion small boat according to the present invention by way of example with reference to the accompanying drawings, wherein: Fig 1 is a cross-sectional view of a boat hull showing an embodiment of the present invention; Fig 2 is a plan view of the boat according to the present invention; Fig 3 is a side view of Fig 2 additionally exemplifying the position of users riding on the boat; Fig 4 is a part of a longitudinal sectional view of the boat according to the present invention showing the installation of ventilation pipes; Figs 5 and 6 are cross-sectional views along the lines V-V and VI-VI of Fig 4, respectively; Figs 7 and 8 are longitudinal sectional views along the lines VII-VII and VIII-VIII of Fig 2, respectively, showing details of the footings; Fig 9 is a perspective view of a footing as shown in the preceding figures; Figs 10(a) and 10(b) are sectional views corresponding to Fig 1 but showing various inclined states of the boat hull. In Figs 1 through 4 the boat hull 1 is composed of a hull member 2 and a deck member 3 both integrally formed from synthetic resin such as FRP and bonded with each other at their fringe portions. The portions surrounded by these hull end deck members are formed as a hermetically sealed space to define an appropriate displacement volume. The hull member 2 has a bottom plate, 20 and side plates 22 and the deck member 3 has rising portions 31 formed at its fringes except at its stern end with their upper end portions folded back to be put upon and bonded with the upper end portions of the hull side plates 22 to form bonded portions 23. By the rising portions 31 and their back-folded portions at their tops are formed the bulwarks 8 defining buoyancy spaces 80 comprised of hermetically sealed spaces. These buoyancy spaces 80 may be merely empty spaces (air-filled) or may be filled with foam plastics. For said purpose, preferably inclined side walls extend longitudinally inside the hollow internal space of the boat between the deck member 3 and the bottom hull 20 of the hull member 2 to separate the associated buoyancy space 80 from the remainder displacement volume formed between the hull and deck members 2, 3. These buoyancy spaces provide the boat hull with a large righting moment, and are set up so that, as shown in Fig 10(a), the hull centre line 10 may be positioned above the draft plane 91 (coinciding with the waterline) when the boat hull is inclined by 90°. The deck member 3 has a seat stand 5 and an operating handle stand 6 projectingly formed on the hull centre line 10 between the bulwarks and these stands and on both sides of these stands are formed decks 30 with open stern ends, in front of these stands is formed a deck 33, and both decks 30 and 33 form a single plane continued to each other. On the above-mentioned operating handle stand 6 is mounted an operating handle 60 and on the rear seat stand 54 are formed a seat 50 and a seat 51 on its rear and front portions, respectively. Under the operating handle stand 6 and the seat stand 5 is formed an engine room 12 in which are arranged an engine 14, a fuel tank 15, etc, by which a propeller (not shown) is rotated by the engine 14 to suck in water through the water suction opening 36 at the hull bottom and inject it backwards in a desired direction through the water passage 37 and then through the horizontally swingable nozzle 38 at the stern to produce a propelling force and a turning force. On the hull centre line 10 are also provided a pair of ventilation pipes 4a and 4b arranged in front and rear, and the upper ends 40 and 42 of these ventilation pipes 4a and 4b, respectively, are both opened above the seat stand 5, as shown in Figs 5 and 6. Fresh air is taken into the engine room 12 through the front ventilation pipe 4a and the air in the engine room 12 is exhausted through the the rear ventilation pipe 4b. The lower ends 41 and 43 of these ventilation pipes 4a and 4b, respectively, are both opened in the engine room 12 and positioned at such a height that they may come above the draft plane of the boat hull when overturned by 180°. Near the lower end portions of these ventilation pipes 4a and 4b are connected ventilation hoses 45 for the fuel tank and ventilation hoses 46 for the battery. Near the rear end portions of the decks 30 are formed footings being preferably integral with the decks 30 as shown in Figs 7 through 9, with a forward inclination so that a driver 11 may be able to keep his feet against them. Each footing 7 has steps 74, 75 on both sides formed by cutting off portions of its width and along these steps 74, 75 is attached a nearly L-shaped support plate 71 on which is fastened, through bolts 73, a flap 72 made of a flexible material such as rubber. In this assembled state, an opening 77 is formed under the support plate 71, and since both end portions of the flap 72 are supported by the rear portions of the steps 74, 75, the flap 72 will not bend forward but can bend rearward, as shown in imaginary lines in Fig 8. With the above-mentioned construction, since the bulwarks 8 on both sides of the boat hull have buoyancy spaces 80 having a large buoyancy, the boat according to this invention has a large righting moment and exhibits an excellent stability for various movements while gliding, even when the boat suffers a large inclining moment due to a rapid turn. Further, in its state inclined sideways by 90° or less, the ventilation pipes 4a and 4b are positioned above the draft plane 91 or 92, as shown in Fig 10(a), and in its state inclined sideways by over 90°, the lower end portions 41, 43 of the ventilation pipes 4a, 4b are positioned above the draft plane 93 or 94, although the upper end portions 40, 42 of the ventilation pipes 4a, 4b are positioned below the draft plane 93 or 94, as shown in Fig 10(b). Thus water can be prevented from coming into the engine room 12 in any inclined state. On the other hand, while gliding normally, two riders can ride astride the seat 50 keeping their feet aginst the footings 7, as shown in Fig 3, to stabilize their bodies. While lying at anchor offshore for fishing and the like, one rider can sit on the front seat 51 facing the front with his feet placed on the deck 33, while the other sits on the seat 50 facing the rear, and the space on board can thus be effectively utlized. Although a fair amount of water is dashed over the decks 30 while gliding, such water will flow into the opening 77, hit the flap 72 bending it rearward as shown in imaginary lines and can be exhausted sternward, as shown by arrows B in Fig 8. Although some water may hit the flap 72 from the rear, as shown by arrow A in Fig 8, the flap 72 will never bend forward since both its end portions are supported at the rear end portions by the step portions 74, 75. Water from the rear is thus checked by this flap 72. According to this invention, since buoyancy spaces with large buoyancy are formed by bulwarks formed at the fringes of the boat hull composed of a hull member and a deck member to bring the hull centre line to its position above the draft plane when the boat is rolled side-ways, as described above, excellent stability can be exhibited for various motions of the boat while preventing water from coming into the boat hull. In particular, by installing ventilation pipes with their lower ends at a depth in the engine room prescribed by this invention, water can be prevented from coming in even when the boat is overturned by 180°.

Claims: A jet propulsion boat comprising a deck member and a hull member, both integrally formed from synthetic resin such as FRP, and bonded with each other at their fringe portions, said deck member (3) comprising bulwarks (8) formed at its fringe portions except at its stern end, a seat stand (5) and an operating handle stand (6) projectingly formed on the hull centre line, and decks (30, 33) formed on both sides of these stands (5, 6), characterized in that said bulwarks (8) define buoyancy spaces (80) to function as floats with the sizes of said buoyancy spaces (80) being set up such that the hull centre line (10) of the float may take its position above the water line (91) when the boat hull is rolled sideways by approximately 90° and ventilation pipes (4a, 4b) are provided, substantially aligned on the hull centre line (10). A jet propulsion boat as claimed in claim 1, characterized in that said buoyancy spaces (80) form hermetically sealed spaces. A jet propulsion boat as claimed in claim 2, characterized in that said buoyancy spaces (80) are separated from the remainder displacement volume defined in between the deck member (3) and the bottom plate (20) of the hull member (2) by preferably inclined side walls extending longitudinally inside the hollow internal space of the boat. A jet propulsion boat as claimed in claim 3, characterized in that said side walls are set to be inclined inwardly. A jet propulsion boat as claimed in any of claims 1 to 4, characterized in that said buoyancy spaces (80) are filled with air. A jet propulsion boat as claimed in any of claims 1 to 5, characterized in that said buoyancy spaces (80) are filled with foam plastic to form floats. A jet propulsion boat as claimed in any of claims 1 to 6, characterized in that the height of the bulwarks (8) corresponds approximately to the height of the seat stand (5), thus forming channel-like deck portions (30, 31) at both sides of said stand (5) extending longitudinally along the boat and being open along the rear stern portion thereof in order to allow water thrown up on the boat being substantially unrestrictedly exhausted. A jet propulsion boat as claimed in any of claims 1 to 7, characterized in that the rear end portions of the decks (30) form integral footings (7) having a forward inclination to allow a rider to keep his feet against them when sitting astride a seat or bench seat (50) provided on the seat stand (5). A jet propulsion boat as claimed in claim 8, characterized in that said footing (7) has steps (74, 75) on both sides formed by cutting off portions of its width with a substantially L-shaped support plate (71) being attached along these steps (74, 75) which, in turn, supports a flap (72) made of a flexible material. A jet propulsion boat as claimed in claim 9, characterized in that the flexible material is rubber. A jet propulsion boat as claimed in claims 9 or 10, characterized in that said flap (72) is attached to the support plate (71) through bolts (73) setting the flap (72) to close an opening (77) formed beneath the support plate (71) and keeping said resilient flap (72) substantially vertical. A jet propulsion boat as claimed in claim 11, characterized in that said opening (77) is formed in the assembled state of the footing (7) with the support plate (71) attached thereto, with both end portions of the flap (72) being supported by the rear portions of the steps (74, 75) in order to avoid the flap (72) being bent forwardly but allowing the flap (72) to be bent rearwardly, respectively. A jet propulsion boat as claimed in any of claims 1 to 12, characterized in that the ventilation pipes (4a, 4b) with their upper ends (40, 42) open above the seat stand (5) and with their lower ends (41, 43) open above the water line of the boat hull when overturned by approximately 180°. A jet propulsion boat as claimed in any of claims 1 to 13, characterized in that an engine room (12) is provided beneath the operating handle stand (6) and the seat stand (5) adapted to receive at least an engine (14) and a fuel tank (15), with the lower ends (41, 43) of the ventilation pipes (4a, 4b) opening into the engine room (12) to be positioned at such a height that their mouth portions reliably opening above the draft plane of the boat hull when the same is overturned by approximately 180°. A jet propulsion boat as claimed in claim 14, characterized in that fresh air is taken into the engine room (12) through the front ventilation pipe (4a) and the air inside the engine room (12) is exhausted through the rear ventilation pipe (4b). A jet propulsion boat as claimed in claim 15, characterized in that ventilation hoses (45) for the fuel tank (15) and ventilation hoses (46) for a battery are connected to the ventilation pipes (4a, 4b) near the lower end portions thereof, respectively. A jet propulsion boat as claimed in claim 13, characterized in that the upper end (40) of the front ventilation pipe (4a) penetrates the seat stand (5) in front of the operating handle stand (6) to open into a space behind the front seat (51) of the boat, said space being communicated with the atmosphere through channels formed by the rim portions of the front seat (51) in conjunction with the supporting seat stand (5). A jet propulsion boat as claimed in claim 11, characterized in that the upper end of the rear ventilation pipe (4b) penetrates the seat stand (5) behind the operating handle stand (6) to open into a space beneath the rear seat (50) of the boat, said space being communicated with the atmosphere through channels formed by the rim portions of the rear seat (50) in conjunction with the supporting seat stand.

Inventors: HATTORI TSUTOMU, HATTORI, TSUTOMU
Applicants: YAMAHA MOTOR CO LTD, YAMAHA HATSUDOKI KABUSHIKI KAISHA
Application year: 1989
Main classification: B63B35
IPC codes: B63B17, B63J2, B63B35, B63B43