Multihulled air cushioned marine vehicle

Claims

What I claim is:

1. In an improved marine vehicle including a propulsion system and with multiple hulls where said multiple hulls are in mechanical communication, the improvement comprising:

port and starboard sidehulls with each sidehull comprising an open bottomed recess that is artificially pressurized with gas from at least one gas pressurization means to thereby form a weight supporting gas cushion when said marine vehicle is waterborne with boundaries of said recess at least partially defined by water contacting substantially rigid sidekeels and a recess aft seal and where, as seen in a calm sea surface water-line with the gas cushions pressurized and the marine vehicle waterborne and moving forward at high speed, the sidehulls are separated by a water clearing wetdeck and are individually substantially boat shaped with narrow bows forward that then diverge, by way of the water contacting substantially rigid sidekeels, and with said sidekeels transforming to more parallel sections over their aft portions and wherein an average total divergence angle of the water contacting sidekeels of said sidehull recess, as measured from the narrow bow to where the sidekeels become more parallel over their aft portions, is on average less than twenty-two degrees and where each of said sidekeels diverges on average over a minimum of one third of its water contacting length going aft from the narrow bow forward to where the sidekeels become more parallel over their aft portions.

2. The improved marine vehicle of claim 1 wherein an average total divergence angle of water contacting gas cushion restraining sidekeels of said sidehull recesses is less than eighteen degrees.

3. The improved marine vehicle of claim 1 which further comprises an artifically pressurized gas cushion that supports part of the weight of the marine vehicle, when said marine vehicle is waterborne, disposed at least partially in an open bottomed recess in a multiple hull with said multiple hull positioned, at least in part, between the port and starboard sidehulls as a third hull and where said third hull's open bottomed recess is at least in part defined by substantially rigid water contacting sidekeels and a recess aft seal and where said third hull, as seen in a calm sea surface waterline when the marine vehicle is waterborne and traveling forward at high speed, is individually boat shaped with a narrow bow forward that then diverges, by way of the substantially rigid water contacting sidekeels, over at least a third of a water contacting length of each of the sidekeels going from the narrow bow forward to where the sidekeels develop more parallel sections over their aft portions.

4. The improved marine vehicle of claim 3 wherein an average total divergence angle of water contacting gas cushion restraining sidekeels of said third hull's open bottomed recess is less than twenty-two degrees.

5. The improved marine vehicle of claim 1 which further comprises a port sidehull and a starboard sidehull retractable water stabilizer assembly where said water stabilizer assemblies are at least partially positioned in the respective port and starboard sidehull gas cushion restraining open bottom recesses and when said water stabilizers are extended to their lowered positions they extend substantially below the sidekeels.

6. The improved marine vehicle of claim 5 wherein the retractable water stabilizer assemblies are, at least in part, of an inverted-T shape with a single vertically oriented strut and with a lower portion of the Inverted-T shape comprising, at least in part, a hydrofoil.

7. The improved marine vehicle of claim 5 wherein said retractable water stabilizer assemblies are, at least in part, configured like a small boat hull.

8. The improved marine vehicle of claim 1 wherein a sidehull's bow disposed proximal a waterline has a forward section of bow that extends forwardly of a lower forward portion of one of the multiple hulls and wherein such forward section of bow further comprises a portion of a sidehull's gas cushion recess.

9. The improved marine vehicle of claim 1 which further comprises multiple vertically oriented water deflecting sidesteps in side surfaces of at least one of the multiple hulls and with at least one of said sidesteps extending upward from proximal a lower portion of a sidekeel to proximal a height of an upper surface of a gas cushion recess.

10. The improved marine vehicle of claim 1 wherein the recess aft seals are, as seen in a vertical transverse plane of the marine vehicle with the marine vehicle being right side up, at least in part of an inverted-V shape.

11. The improved marine vehicle of claim 1 wherein the recess aft seals are, as seen in a vertical transverse plane of the marine vehicle, at least in part of an inverted-V shape.

12. The improved marine vehicle of claim 1 which further comprises an air flow restricting seal on an underside of a wetdeck, where said wetdeck is in communication with a sidehull and connects said sidehull to another hull member, with said air flow restricting seal proximal an aft portion of said wetdeck and whereby said wetdeck is in mechanical communication with the port and starboard sidehulls.

13. The improved marine vehicle of claim 1 which further comprises a venturi positioned as part of a duct that interconnects port and starboard sidehull open bottomed recesses whereby when separate gas pressurization means are employed to pressurize the port and the starboard sidehull open bottomed recesses the venturi dampens pressure pulses between said separate port and starboard recesses and the gas pressuization means.

14. The improved marine vehicle of claim 1 which further comprises a gas flow restricting means that is independent of a water level in a gas cushion recess to restrict gas flow leakage out through one of the gas pressurization means in such instance where the gas pressurization means is inoperative.

15. The improved marine vehicle of claim 14 wherein the gas flow restricting means is a flap-like device disposed downstream of the gas pressurization means.

16. The improved marine vehicle of claim 14 wherein a gas pump can evacuate gas from the gas cushion when the gas flow restricting means is positioned to restrict gas flow.

17. The improved marine vehicle of claim 1 which further comprises a water stabilizer positioned, at least in part, proximal to and between a forward portion of the port and starboard sidehulls.

18. The improved marine vehicle of claim 17 wherein the water stabilizer is, at least in part, boat shaped.

19. The improved marine vehicle of claim 17 wherein the water stabilizer is, at least in part, a hydrofoil.

20. The improved marine vehicle of claim 17 wherein the water stabilizer is at least partially retractable into a recess in a wetdeck.

21. The improved marine vehicle of claim 1 which further comprises a sidewing with said sidewing being, on average, more than fifty percent of an overall length of the marine vehicle.

22. The improved marine vehicle of claim 21 wherein at least a portion of said sidewings are retractable.

23. The improved marine vehicle of claim 1 which further comprises outrigger wings extending outward beyond the sidehulls with said outrigger wings further comprising downwardly extending outrigger hulls.

24. In an improved marine vehicle including a propulsion system and with multiple hulls where said multiple hulls are in mechanical communication, the improvement comprising:

an artificially pressurized gas cushion that supports part of marine vehicle weight, when said marine vehicle is waterborne, disposed at least partially in an open bottomed recess in a multiple hull with said multiple hull positioned, at least in part, between port and starboard sidehulls as a third hull that is in mechanical communication with and separated from said port and starboard sidehulls by water clearing wetdecks and where said third hull's open bottomed recess is at least in part defined by water contacting substantially rigid sidekeels and a recess aft seal and where said third hull, as seen in a calm sea surface waterline when the marine vehicle is waterborne and traveling forward at high speed, is individually boat shaped with a narrow bow forward that diverges, by way of the substantially rigid water contacting sidekeels, over at least one third of a water contacting length of said sidekeels going from the narrow bow forward to where the sidekeels develop more parallel sections aft and wherein an average total divergence angle, from the narrow bow forward to where the sidekeels become more parallel, of said sidekeels is less than twenty-two degrees.

25. The improved marine vehicle of claim 24 wherein an average total divergence angle of water contacting gas cushion restraining sidekeels of said third hull's open bottomed recess is less than eighteen degrees.

26. The improved marine vehicle of claim 24 which further comprises vertically oriented water deflecting sidesteps in side surfaces of at least one of the multiple hulls wherein at least one of said sidesteps has a chine that extends downwardly going from forward to aft to proximal a level of a chine preceding said sidestep.

27. The improved marine vehicle of claim 24 wherein the third hull's recess aft seal is, over a majority of its width as seen in a vertical transverse plane of the marine vehicle, angled to horizontal.

28. The improved marine vehicle of claim 24 which further comprises a gas flow restricting means that is independent of a water level in a gas cushion recess to restrict gas flow leakage out through a gas pressurization means in such instance when said gas pressurization means is inoperative.

29. In an improved marine vehicle including a propulsion system and with multiple hulls where said multiple hulls are in mechanical communication, the improvement comprising:

port and starboard sidehulls with each sidehull comprising an open bottomed recess that is artificially pressurized with gas from at least one gas pressurization means to thereby form a weight supporting gas cushion with boundaries of said recess at least partially defined by water contacting substantially rigid sidekeels and a recess aft seal when said marine vehicle is waterborne and where, as seen in a calm sea surface waterline with the gas cushions pressurized and the marine vehicle is waterborne and moving forward at high speed, the sidehulls are separated by a water clearing wetdeck and are individually substantially boat shaped with narrow bows forward that then diverge, by way of the sidekeels, to more parallel sections aft and wherein an average total divergence angle of the water contacting sidekeels of said sidehull recess is less than twenty-two degrees going from the narrow bow to where the sidekeels become substantially more parallel and which further comprises vertically oriented water deflecting sidesteps in side surfaces of at least one of the multiple hulls wherein at least one of said sidesteps has a chine that extends downwardly going from forward to aft to proximal a level of a chine preceding said sidestep.

30. In an improved marine vehicle including a propulsion system and with multiple hulls where said multiple hulls are in mechanical communication, the improvement comprising:

port and starboard sidehulls with each sidehull comprising an open bottomed recess that is artificially pressurized with gas from at least one gas pressurization means to thereby form a weight supporting gas cushion, when said marine vehicle is waterborne, with boundaries of said recess at least partially defined by water contacting substantially rigid sidekeels and a recess aft seal and where, as seen in a calm sea surface water-line with the gas cushions pressurized and the marine vehicle waterborne and moving forward at high speed, the sidehulls are separated and substantially boat shaped with narrow bows that then diverge, by way of the sidekeels, to more parallel sections aft and which further comprises a port and a starboard sidewing with said port and starboard sidewings extending outward beyond their respective port and starboard sidehulls such that, when the improved marine vehicle is at least primarily airborne, said sidewings provide much of the aerodynamic lift required to support the improved marine vehicle and which further comprises at least one water stabilizer that is positioned proximal a forward portion of the improved marine vehicle and that extends downward below the sidekeels whereby said at least one water stabilizer provides stability during water landing of the improved marine vehicle.

31. The improved marine vehicle of claim 30 which further comprises a downwardly extending outrigger hull in mechanical communication with said sidewing.

32. The improved marine vehicle of claim 30 wherein at least a portion of said sidewing is retractable.

33. The improved marine vehicle of claim 30 wherein the sidewing further comprises a downwardly extending wingcap.

34. The improved marine vehicle of claim 30 wherein said at least one water stabilizer is, at least in part, shaped like a boat hull.

35. The improved marine vehicle of claim 30 wherein a wetdeck that connects the sidehulls is, at least in part, airfoil shaped.

36. In an improved marine vehicle including a propulsion system and with multiple hulls where said multiple hulls are in mechanical communication, the improvement comprising:

port and starboard sidehulls with each sidehull comprising an open bottomed recess that is artificially pressurized with gas from at least one gas pressurization means to thereby form a weight supporting gas cushion when said marine vehicle is waterborne and with boundaries of said recess at least partially defined by substantially rigid water contacting sidekeels and a recess aft seal and where, as seen in a calm sea surface waterline with the marine vehicle waterborne and moving forward at high speed, the sidehulls are separated by a water clearing wetdeck and are each substantially boat shaped with narrow bows that then diverge by way of the substantially rigid water contacting sidekeels such that an average total divergence angle of the sidekeels of each sidehull is less than 22 degrees and wherein said sidekeels then become more parallel from at least one third of a distance aft of the narrow bow forward and which further comprises a port and a starboard sidewing with said port and starboard sidewings extending outward beyond their respective port and starboard sidehulls such that, when the improved marine vehicle is at least partially airborne, said sidewings provide much of the aerodynamic lift required to keep the improved marine vehicle at least partially airborne.

37. The improved marine vehicle of claim 36 which further comprises at least one water stabilizer positioned proximal a forward portion of the improved marine vehicle whereby said at least one stabilizers provides stability during takeoff and landing of the improved marine vehicle.

38. The improved marine vehicle of claim 37 wherein said water stabilizer is, at least in part, shaped like a boat hull.

39. The improved marine vehicle of claim 37 wherein said water stabilizer comprises, at least in part, a hydrofoil.

40. The improved marine vehicle of claim 36 which further comprises a downwardly extending outrigger hull in mechanical communication with said sidewing.

41. The improved marine vehicle of claim 36 wherein at least a portion of said sidewing is retractable.

42. The improved marine vehicle of claim 36 wherein the sidewing further comprises a downwardly extending wingcap.

43. The improved marine vehicle of claim 36 wherein the wetdeck that connects the sidehulls is, at least in part airfoil shaped.

44. In an improved marine vehicle including a propulsion system and with multiple hulls where said multiple hulls are in mechanical communication, the improvement comprising:

port and starboard sidehulls with each sidehull comprising an open bottomed recess that is artificially pressurized with gas from at least one gas pressurization means to thereby form a weight supporting gas cushion when said marine vehicle is waterborne with boundaries of said recess at least partially defined by substantially rigid water contacting sidekeels and a recess aft seal with said recess aft seal, as seen in a vertical transverse plane of the improved marine vehicle, angled to horizontal over a majority of its width and where, as seen in a calm sea surface waterline with the gas cushions pressurized and the marine vehicle waterborne and moving forward at high speed, the sidehulls are separated by a water clearing wetdeck and are individually substantially boat shaped with narrow bows forward that then diverge, by way of the substantially rigid water contacting sidekeels, to become more parallel over their aft portions and where each of said water contacting sidekeels on average diverges over a minimum of one third of its water contacting length going from the narrow bow forward aft to where the sidekeels become more parallel over their aft portions.

45. The improved marine vehicle of claim 44 which further comprises a port and a starboard sidewing with said sidewings providing a majority of the lift required to support the marine vehicle when said marine vehicle is primarily airborne.

FIELD OF THE INVENTION

The instant invention describes marine vehicles that operate in a surface effect condition by entrapping a cushion(s) of artifically pressurized gas between the vehicle and a water surface and/or a ram effect of ambient air that is sandwiched between the vehicle and a water or other surface at higher vehicle speeds. The first are most commonly called hovercraft or Surface Effect Ships (SES's) and the latter Wing in Ground Effect (WIG), Wing in Surface Effect Craft, or simply wingships. The common thread of all of these is that the pressurized gas disposed between the vehicle and the supporting medium carries most of vehicle weight. In any case, overall efficiencies of the SES are much greater than conventional marine vehicles and overall efficiencies of the WIG are much greater than commercial aircraft.

Applicant's earlier developments of marine vehicles using artifically pressurized supporting gas cushions have been successful and have resulted in a number of vehicles being built. What promises to be far superior to any of its predecessors is now called the SeaCoaster marine vehicle that uses multiple hulls with a long and slender air cushion in at least one of such hulls. The multiple hulls have very fine entry bows and controlled divergence of their gas cushions back to a point where the sides of the gas cushions become parallel in the preferred embodiments. Applicant has conducted extensive model tests to establish allowable ranges of divergence of the gas cushions and has also devised an optional new knife type bow that is now referred to as the SeaSaber bow for its wave slicing abilities. The clearly defined low divergence angles of the gas cushions are invaluable for rough sea operation of SeaCoaster. When coupled with the optional SeaSaber bow there are further advantages realized in some speed and sea conditions that makes SeaCoaster an exceptionally good sea boat.

de Pingon, French Patent 0271372 has catamaran-like sidehulls in a marine vehicle with pressurized air cushions under each sidehull; however, the entry of each of his sidehulls is rather blunt and the total divergence of his air cushion sides, as seen in a waterline plane of the hull, is very abrupt with total divergence angles of over 45 degrees. Applicant has established that such divergence angles will contribute to a totally unacceptable ride in rough seas. As a point in fact, applicant limits the total divergence angle of SeaCoaster's gas cushions to less than 22 degrees, with at least part of such divergence preferably on either side of a vertical longitudinal plane of the hull. A divergence angle closer to 15 degrees is optimum while under 18 degrees is set as a good target for good rough sea ride qualities combined with enough divergence to obtain sufficient cushion area to properly support the vehicle. Some discussion is now in order regarding the relevance of the proper divergence angle of the gas cushion from the narrow bow going aft to where the substantially rigid sidekeels bounding a recess in the hull become more parallel. This angle is referred to as the total divergence angle of the sidekeels. First, a rectangular gas cushion with a squared off front end and widely spaced substantially parallel sidehulls that are not joined by a narrow bow forward will actually be the most efficient in calm seas as that squared off bow arrangement has the largest gas cushion area and hence the lowest most efficient gas cushion pressure, the bow seal will actually be clear of the water at high speed resulting in minimum bow seal drag, and the sidekeels will be parallel over their entire length which is a least drag situation. However, such squared off bow seal designs have very poor rough sea performance. Tests have been conducted on Applicant's narrow pointed bow designs with reduced sidekeel total divergence angles. Bow movement or pitching in rough seas starts to fall into an acceptable range at just under 22 degrees total divergence angle. It is a compromise as to how far to lower the total divergence angle and still have sufficient gas cushion area to properly support the vessel. Tests with a sidekeel divergence angle of just under 18 degrees showed a good compromise between rough sea ride qualities and sufficient cushion area. Therefore, the necessary limits of sidekeel divergence angle for the instant invention are less than 22 degrees with less than 18 degrees preferred. Also, SeaCoaster's SeaSaber bow knifes through waves and also gives a longer water-line length which is invaluable for this high speed marine vehicle. In its preferred embodiment, SeaCoaster combines the SeaSaber bow with a very fine entry gas cushion which has total average divergence of less than 18 degrees, a series of vertically high water friction reducing steps down the length of its hulls, and a unique retractable water stabilizer system. Any one of these features, taken individually or collectively, make the instant invention far superior to and widely separate it from de Pingon.

Wilson, U.S. Pat. No. 3,191,572; Gunther U.S. Pat. No. 3,473,503; and Crowley, U.S. Pat. No. 3,742,888 present multiple air cushion hulls. Wilson and Gunther do not have open bottomed recesses in their individual hulls but rather plates with air discharge holes drilled in them as can be seen in FIG. 7 of Gunther and FIG. 2 of Wilson. Further, Gunther does not have air cushion sidekeels on his sidehulls and neither Gunther nor Wilson have recess aft seals in their multiple hulls which is a critical part of the instant invention as such aft seals are required to maintain a pressurized air cushion. Yet another difference is that Wilson's water contacting sidekeels are parallel from their forwardmost portions and do not diverge as specified in the instant invention. Wilson has upwardly curved angled surfaces that become bows forward; however, they, very importantly, do not make water contact in a calm sea surface when the blowers are operating and his boat is traveling forward at high speeds. Crowley, in his closest concept as shown in his FIGS. 9 and 10, does not have individual boat shaped multiple hulls but rather simply multiple air cushions all having a common center bow. As such, neither Wilson, Gunther, nor Crowley have concepts that resemble applicant's instant SeaCoaster invention.

Distinctions are also noted from applicant's U.S. Pat. Nos. 5,176,095 and 5,415,120 that show a total gas cushion divergence angles of over 30 degrees and also from an article in the May 1992 issue of "Ship & Boat International" magazine that shows applicant's earlier concepts where gas cushion divergence angles of approximately 30 degrees are shown. Neither of these divergence angles are acceptable for tolerable seakeeping characteristics. Importantly also, neither applicant's earlier issued patent nor the "Ship & Boat International" article talk of the SeaSaber bow or water stabilizer systems that are preferred components of the instant invention's SeaCoaster hull concepts.

SeaCoaster offers attention to details including the optional use of a venturi positioned in an interconnecting duct that connects gas cushion recesses in separate multiple hulls. The benefit of such a venturi is that is restricts gas pressure pulses from traveling from one multiple hull's gas cushion to another and thereby helps insure a smooth bounce free ride. Freygang, U.S. Pat. No. 2,399,670, uses a venturi as part of an air induction system for inflating a life raft. It is only used when inflating the raft and does not in any way connect two separate gas cushions in a multiple hull air cushion boat. As such, there is little or no resemblance to applicant's instant SeaCoaster invention.

A very serious additional benefit is the use of water stabilizers in the form of a lifting hull(s) or hydrofoil(s) with the SeaCoaster instant inventive hull. The hydrofoils especially reduce pitch of SeaCoasters bows in very rough seas. In their ideal form, these water stabilizers can be retracted up into the gas recesses in the hulls during calm sea or shallow water operation but lowered during operation in heavy seas. Applicant's model tests have shown at least a fifty percent reduction in bow pitch with hydrofoils in use.

Meyer, Jr., U.S. Pat. No. 3,968,762, offers hydrofoils that retract into a single air cushion generic flexible seal SES. He does not offer a multiple hull air cushioned craft as is applicant's instant invention and therefore cannot offer multiple hydrofoils that retract into air cushion recesses. In its most important arrangement, SeaCoaster utilizes retractable hydrofoils widely separated in port and starboard sidehull air cushion recesses. Cathers, et al, U.S. Pat. No. 3,141,436, presents hydrofoils that extend inwardly from outboard sidewalls in a two air cushion craft where such cushions are separated by a narrow skeg and further are each of movable fore and aft seal SES arrangements. Cathers has no way to retract his hydrofoils and does not have boat shaped multiple hulls as does the instant invention so he bears little resemblance to the instant invention. Johnson, U.S. Pat. No. 3,456,611, is a catamaran with hydrofoils but with no gas cushion recesses to withdraw them into so therefore offers little resemblance to the instant invention.

Another important feature of the SeaCoaster instant inventive hull is its use of sidesteps to reduce water friction by keeping water off of the sides of the multiple hulls. This is accomplished by a series of downwardly extending steps that start about midship. Very importantly, the chines of SeaCoaster's sidesteps start highly elevated and swoop down to proximal the level of the chine preceding such sidestep. This is not so of either Pipkorn, U.S. Pat. No. 4,907,520, nor With, U.S. Pat. No. 3,977,347. Pipkorn uses a vertical inset into the side of his hull that remains essentially constant in elevation over its entire after length. With has outwardly extending rearwardly facing steps, noted as 3 in his FIG. 3, and does not have the downwardly swooping chine steps of the instant invention either. As such, neither the patents of Pipkorn nor With have relevance to the instant invention's very efficient sidesteps with downwardly swooping chines.

SeaCoaster lends itself ideally to transformation to an air-borne mode as a WIG as vehicle speed is increased substantially. For example, a wide beam 100 foot SeaCoaster would achieve takeoff speeds to WIG operation at about 110-130 knots. A difficulty of other WIG types is getting up to takeoff speeds efficiently. Various means have been attempted including the Power Augmented Ram Wing (PAR) which simply rams the exhaust of turbojet engines or air propellers under the WIG's wing at lower speeds to obtain sufficient lift. This is an overpowering approach and generally requires extra engines that are not used during high speed cruising WIG operation. SeaCoaster optionally applies outrigger hulls attached to outrigger wings outboard of its air cushioned sidehulls that are beneficial for stability and for added lift. Further, additional winglets can be applied outboard of the outrigger hulls and such would normally include downwardly extending wing caps for improving aerodynamic efficiency.

Bixel, Jr., U.S. Pat. No. 5,105,898 approaches the WIG takeoff problem with a hovercraft or SES that becomes a WIG after takeoff speeds are reached. This is a workable approach as the SES is a very efficient high speed marine vehicle. Bixel's shortcoming has to do with the shortcomings of all SES's related to the movable seals fore and aft between his sidehulls. These movable seals have poor seakeeping abilities, contribute to a pulsing of pressures in the gas cushion that is felt by passengers as severe jolts, and are subject to high maintenance. Also, Bixel, Jr. does not have a water stabilizer system to improve ride qualities and to augment takeoff and/or landing from SES waterborne into the WIG airborne mode or vice versa as does the preferred variant of SeaCoaster.

The instant invention offers advancements over applicant's earlier inventions as well as over the prior art. These advancements are discussed in some detail in the following sections.

SUMMARY OF THE INVENTION

The object of the instant invention is to provide a superior marine vehicle that is, in its majority, supported by pressurized gas.

It is a directly related object of the invention that gas for pressurized gas cushions can be supplied by artificial means.

It is another object of the invention that at least part of the pressurized gas for support of the marine vehicle can be obtained by a gas compression effect that occurs between the vehicle and a supporting surface when the vehicle is traveling forward at high speeds.

An important object of the invention is that multiple hulls are used with pressurized gas supplied to a recess in at least one of such multiple hulls by artificial means such as powered blowers.

It is a related object of the invention that, as seen in a calm sea surface with the gas cushion(s) pressurized and the marine vehicle moving forward at high speed, the sidehulls form either symmetrical or unsymmetrical boat shaped patterns on the water surface with narrow bows that become more parallel going aft.

A related object of the invention is that an aft portion of a pressurized gas recess can be comprised of surfaces angled to horizontal, at least over a portion of its longitudinal lengthened that such aft portion can be called a recess aft seal.

Another object of the invention is that another recess seal can be at least partially positioned in a gas cushion recess forward of the recess aft seal.

Yet another object of the invention is that angled surfaces can be applied to an underside of structure that connects two of the multiple hulls.

It is a related object of the invention that

Another object of the invention is that multiple hulls can include two or more hulls in mechanical communication.

It is a related object of the invention that two or more pressurized gas cushions disposed in separate hulls can be connected through hull interconnecting structure such as ducts.

A directly related object of the invention is that a duct interconnecting pressurized gas cushions in separate hulls can include a venturi to thereby restrict pressure disturbances from traveling between the gas cushions.

It is another object of the invention that movable structure, such as flaps, disposed in blower ducts can be used to seal off gas flow through a blower that may be inoperative.

It is a related object of the invention that a gas pumping device can be used to maintain a multiple hull gas cushion pressurized when the main blowers are inoperative.

It is another related object of the invention that a gas pumping device can be used to evacuate gas from a multiple hull gas cushion when the main blowers are inoperative and thereby lower the profile of the inventive hull.

It is an object of the invention that average total divergence of the sides of the gas cushion be less than 22 degrees for good ride qualities and low resistance.

It is a directly related object of the invention that a further refinement places the total divergence of the sides of the gas cushion at less than 18 degrees for best ride qualities and lowest resistance.

It is a further and optional object of the invention that a forwardly