Multihulled air cushioned marine vehicle

An improved multi-hull gas cushion supported marine vehicle that is, in its preferred embodiment, capable of transition to airborne surface effect operation is presented. This marine vehicle, known as SeaCoaster, has optional elongated knife shaped bows that slice into waves, very fine entry and low angle of divergence supporting gas cushions, water rejecting steps that extend high onto the sidehulls, and retractable water stabilizers to insure optimum performance in heavy seas. The retractable water stabilizers are in the form of inverted-T hydrofoils and/or small boat shaped members. Several variations of hydrofoil configurations are presented. It also has special, normally inverted-V shaped, gas cushion and wetdeck aft seals to insure minimum effect of wave impacts in those areas. The gas pressurization system normally includes powered blowers where a flap-like sealing device can be installed to seal gas leakage. This allows a gas pressurizing blower to either maintain cushion gas pressure for minimum draft or evacuate the gas cushion from minimum above water profile. The latter is valuable for patrol boat applications where a minimum radar signature is desired. Connecting ducts between gas cushions can include venturi's that restrict pressure pulses in one gas cushion from traveling to another gas cushion. Retractable or fixed sidewings are optionally proposed to add aerodynamic lift when SeaCoaster is airborne. These sidewings may include outrigger hulls for added stability and improved aerodynamic efficiencies.

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 () 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 
extending saber-like bow be applied to a hull for best rough sea 
performance. 
It is a directly related object of the invention that such a saber-like bow 
be proximal a calm sea waterline and extend forwardly of its intersection 
of a lower portion of a normal bow of the vehicle when the gas cushions 
are pressurized. 
It is another related object of the invention that such saber-like bow can 
contain part of an air cushion recess. 
Another object of the invention is that a series of vertically high 
sidesteps, that preferably extend from proximal a sidekeel to a height 
that approximates the height of a gas cushion recess, can be recessed into 
the sides of the multiple hulls where such sidesteps reduce vehicle 
resistance in both calm and rough seas. 
It is a directly related object of the invention that such sidestep's have 
chines that extend downwardly from their forward position to reform a 
similar shape prior to following sidestep. 
A related object of the invention is to have the last step in the series 
have a simple recess aft of it to thereby minimize wetted area resistance. 
It is yet another object of the invention that a water stabilizing system 
can be used to improve vehicle ride qualities in rough seas. 
It is a related object of the invention that the water stabilizing system 
can include a hydrofoil. 
Another object of the invention is that a water stabilizing hydrofoil 
structure are, in the main, preferably of an inverted-T shape. 
A directly related object of the invention is that the hydrofoils, and 
their supporting struts, can be airfoil shaped, cleaver or supercavitating 
shaped, or base vented by gas. 
It is a related object of the invention that any water stabilizers applied 
to the invention can be retracted from the water surface. 
It is another object of the invention that any water stabilizer can be 
locked into position, either up or down. 
Yet another object of the invention is that movement of the foils can be 
accomplished by an actuator where such an actuator is preferably a fluid 
actuator. 
It is still another related object of the invention that the water 
stabilizer can be retracted into a gas cushion recess. 
It is another related object of the invention that said hydrofoil can be 
changed in position during vehicle operation so that it can accomplish at 
least part of vehicle trim requirements. 
It is yet another object of the invention that the hydrofoil can be angled 
to accomplish a vehicle bow up attitude, at very high speeds, to aid in 
getting the vehicle into an airborne mode. 
It is yet another related object of the invention that the water stabilizer 
can further comprise a small boat shaped member. 
Another object of the invention is that both water and air propulsion 
systems can be applied to the vehicle. 
It is a directly related object of the invention that a common power source 
can be used, at least partially, for both the water and air propulsion 
systems. 
It is another related object of the invention that the common power system 
can drive the air or water propulsion system independently. 
Another feature of the invention is that sidewings can be utilized to aid 
in vehicle aerodynamic lift. 
It is a related object of the invention that such sidewings can further 
comprise outrigger type hulls. 
It is another related object of the invention that such sidewings can be 
retractable. 
It is another object of the invention that such sidewings can be more than 
sixty percent of the beam of the parent hull. It is yet another related 
object of the invention that retractable winglets that may further include 
wingcaps to improved aerodynamic efficiencies can be used to improve 
aerodynamic lift. 
The invention will become better understood upon reference to the drawings 
and the detailed description of the invention which follow in which:

DETAILED DESCRIPTION 
FIG. 1 presents a profile view of the inventive multihull marine vehicle 40 
showing a starboard sidehull 60 and a third hull 62, in this case on main 
hull centerline, in this FIG. 1 triple hull arrangement. In this instance, 
the vehicle 40 is riding steady in a heavy sea as indicated by waterline 
46. This smooth ride is made possible by the SeaSaber bows 71 that slice 
and part waves and by the water stabilizer 41 which in this case includes 
a hydrofoil 84. Resistance is kept to a minimum by the vertically deep 
sidesteps 68 and their following straight side inset 69. As waves pass 
down the vehicle sides, they see less hull to wet due to the sidesteps 
that normally extend from proximal the sidekeels 73 to about the same 
height as the depth of the gas cushion recess inside. It is important to 
note that sidesteps 68 taper back down such that their chines 70 wind up 
at a similar elevation as a chine 70 forward of said sidestep 68. Also 
shown in FIG. 1 are a water propulsor 48, air propulsor 49, aerodynamic 
stabilizer 72, chine 70, main bow stem 77, wetdeck 79, wetdeck aft seal 
81, sidekeel 73 which is also the boundary of the air cushion recess, air 
flow arrows 45, starboard sidehull 60, and third hull 62. 
FIG. 2 is a bow view of the marine vehicle 40 showing sidehulls 59, 60 and 
third hull 62 which in this case is on main hull centerline, and their 
SeaSaber bows 71. Note that the SeaSaber bows are essentially knife or 
saber shaped, as seen in this bow view, to enable a clean wave slicing 
effect. Note that the main bow stem 77 intersects with the SeaSaber bow 71 
proximal a waterline 46 in the preferred embodiment. Wetdecks 79 are also 
shown. 
FIG. 3 is a stern view of the marine vehicle 40 which shows the preferred 
inverted-V shaped seals 81 between the multiple hulls 59, 60, 62. This 
inverted-V shape serves three purposes: first it directs clean water to 
the water propulsor 48, second it provides a low impact design in heavy 
seas, and third it forms an air dam for escaping ram air thereby insuring 
maximum pressure for lift in the wetdeck areas between the hulls. 
FIG. 4 presents a bottom plan view of the triple hulled SeaCoaster marine 
vehicle 40 of FIG's 1-3. Very importantly, note the extremely fine entries 
on the SeaSaber bows 71 and the shallow average total divergence angles 
(.beta.) of the water contacting sidekeels that occur from the point of 
the divergence forward to a point where the sidekeels 73, which are also 
the sealing edge of the gas cushion recesses 47, become essentially 
parallel. Note that by definition here it is considered that this sidekeel 
divergence is measured in a calm sea surface waterline when an air cushion 
is pressurized and supporting craft weight and the marine vehicle is 
traveling forward at high speed. High speed is defined as over water 
speeds of greater than fifteen knots for purposes of this application. It 
is also considered that the multiple hulls, as seen in the same calm sea 
surface as previously defined, will be seen as essentially boat shapes 
with narrow bows that then diverge, by way of the sidekeels, to more 
parallel sections. 
The point where the sidehull keels 73 become essentially parallel is noted 
to normally be at about one third to one half the waterline length of the 
vehicle 40. It is to be noted that partial angles of divergence (.rho.) 
are shown in FIG. 4 where they are essentially equal on either side of a 
longitudinal vertical plane 76 in this symmetrical hull depiction. 
However, it is not necessary that the partial angles of divergence (.rho.) 
be equal and it is quite possible that all of the total average divergence 
angle (.beta.) can occur to one side of a longitudinal vertical plane 76. 
Extensive tests of Applicant's narrow bow air cushion boat designs, both 
model and full scale, have defined optimum total divergence angles 
(.beta.). 
By way of discussion, a rectangular gas cushion with a squared off front 
end and substantially parallel widely separated sidekeels will actually be 
the most efficient in calm seas as it has the largest 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 substantially 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 designs with reduced sidekeel total divergence angles 
(.beta.). These tests have shown that bow movement or pitching starts to 
fall into an acceptable range at a total divergence angle (.beta.) of 
slightly less than 22 degrees. Keep in mind that reducing the total 
divergence angle (.beta.) also reduces the available cushion area which 
means that a higher less efficient gas cushion pressure is required. In 
summary, tests of Applicant's designs have established that the optimum 
total divergence angle (.beta.) for good rough water performance coupled 
with acceptable air cushion areas is less than 22 degrees with less than 
18 degrees and down to 15 degrees appearing near optimum. The 18 and 22 
degree limitation definitions of total divergence angle (.beta.) are 
strong and necessary requirements of the instant invention that are not 
taught by any of the prior art. The divergence angle (.beta.) limitations 
were only arrived at after extensive and expensive test programs. 
Also shown in FIG. 4 are blower discharge openings 44 and connecting ducts 
67, sidesteps 68, recess aft seals 80, and sidewall side inset 69 behind 
the last sidestep. Note that the starboard water stabilizer 41 is raised 
into the starboard sidehull's open bottomed recess 92 and lowered on the 
port side in this instance which was done for illustrative purposes only. 
It is not considered necessary that all of the multihulls to contain 
pressurized gas cushions for the invention to function. For example, the 
third hull 62 of FIG. 4 could be of a conventional solid V-hull 
configuration and could also only extend for a portion of the distance 
back from the bow to stern if desired. 
FIG. 5 is a cross section, as taken through line 5--5 of FIG's 1 and 4, 
that shows the air cushions 47 in a pressurized condition as disposed in 
open bottomed recesses 92 in multiple hulls. Note that the interconnecting 
ducts 67 have venturis 78 built in which is done to restrict pressure 
pulses from traveling from one gas cushion to another. 
FIG. 6 is a cross section, as taken in a vertical transverse plane of the 
vehicle defined as being through line 6--6 of FIG. 4, that clearly shows 
the optional SeaSaber bows 71 at this position having very sharp wave 
slicing upper portions that go to flatter portions on their lower sides 
where the gas recesses 47 are developing. This can best be seen upon 
examination of the center hull where the gas cushion recess 47 is more 
developed due to the more forward extension of the center hull. The bow 
stem 77 intersects the SeaSaber bow 71 just forward of this vertical 
transverse plane in this instance. FIG. 6 also shows vertical longitudinal 
planes 76 of the vehicle 40. Note that in this instance the center hull 
shown is normally referred to as the third hull and that more than three 
multiple hulls can be used in the SeaCoaster concept. 
FIG. 7 is a cross sectional view of an aft portion of the marine vehicle 
40, as taken through a vertical transverse plane noted as 7--7 of FIG. 4, 
that shows the preferred inverted-V shaped recess aft seals 80 and wetdeck 
aft seals 81. 
FIG. 8 is a cross sectional view, as taken though a vertical longitudinal 
plane noted as line 8--8 of FIG. 4, that shows a powered blower 43, water 
stabilizer 41 in a retracted position, hydrofoil 84, water stabilizer 
actuator 42, and gas sealing mechanism 75, normally a flap-like device, 
that can be resiliently biased or powered for movement, that acts to 
prevent cushion gas pressure from escaping through an inoperative blower 
43. The gas sealing mechanism can also act to prevent gas from entering 
the open bottomed recess 92. 
The ability to seal the open bottomed recess 92 is several fold. First, it 
allows gas to enter the recess through duct 67 in the event of a blower 
failure. Second, it allows a gas pressurizing device 86 to maintain a 
SeaCoaster on cushion for extended periods at dockside, etc. with the main 
blower(s) 43 off and their ducts sealed. Third, it allows a SeaCoaster to 
be sucked down onto the water by having the gas pressurizing device 86 
exhaust gas from the recess 92. The latter item is valuable for patrol 
craft where a minimum radar signature is desired when standing on station 
and for certain docking situations. The operation of the pressurizing 
device 86 is controlled by valve 86. To pressurize, A is open to C and D 
is open to B. To exhaust, B is open to C and D is open to A. It is to be 
noted that a relatively good seal is required by the gas sealing mechanism 
75 for the pressurizing device 86 to be able to pressurize and exhaust 
properly. As such, a value of a 90 percent or better seal against gas 
leakage is prescribed for this seal. 
FIG. 9 is a similar cross sectional view to that presented in FIG. 8, as 
taken through line 9--9 of FIG. 4, that shows the blower 43 operating and 
gas sealing mechanism 75 therefore open. Also, in this instance, the water 
stabilizer 41 is down and acting as a hydrofoil. 
FIG. 10 is a cross-sectional view, as taken through line 10--10 of FIG. 4, 
that shows water propulsor 48, air propulsor 49, and their common prime 
mover engine 74. Note that it is possible for the common prime mover 
engine to drive either the water and air propulsors at the same time for 
independently. This would normally be accomplished by means of disengaging 
clutches that are considered part of the common prime mover engine 
package. In the preferred embodiment the water propulsor is disengaged 
when the vehicle is airborne. Note that the wetdeck 79 is shaped like the 
underside of a low speed aircraft wing to obtain maximum aerodynamic lift. 
FIG. 11 presents a bow on view of the same type of marine vehicle 40 as 
presented in FIG's 1-10 but with only two multi-hulls that are therefore 
in a catamaran configuration. Note that for purposes of this application 
the term multiple hulls is defined to mean two or more hulls. FIG. 10 
shows a variation of a retractable water stabilizer 41 which in this case 
is positioned between the sidehulls as a landing hull member 85. 
FIG. 12 is a cross sectional view, as taken through line 12--12 of FIG. 11 
that shows the water stabilizer 41 at a high angle of attack to therefore 
aid in takeoff or landing of the vehicle 40 from waterborne to a flying or 
airborne mode at very high speeds. For purposes of definition, waterborne 
speed is meant to mean speeds of up to about 120 knots and airborne speeds 
meant to mean speeds anywhere from about 80 knots or more in this 
application. By way of further definition, high waterborne speeds are 
hereby noted to be waterborne speeds of 15 knots or more. Takeoff speeds 
are generally above about 80 knots. Also, note that the angle of attack of 
the vehicle 40 shown in FIG. 12, with the water stabilizer(s) 41 angled as 
shown, is the preferred landing configuration and that the preferred 
approach to landing A SeaCoaster is to set the recess aft seals down first 
and then rotate so that the water stabilizer 85 forward contacts the 
water. The blower engines would be actuated before making a landing 
approach to insure availability of cushion pressure. 
FIG. 13 is a cross sectional view, as taken through line 13--13 of FIG. 12, 
that shows the marine vehicle 40 in its wing in surface effect airborne 
flight mode. Note that the air propulsor 49 is the means of generating 
thrust in both FIGS. 12 and 13. 
FIG. 14 presents an isometric view of the preferred configuration of a 
water stabilizer assembly 41 which in this case is in the form of a simple 
inverted-T with the strut 52 making up the stem of the T and the hydrofoil 
84 the top, or bottom in this illustration, of the T. Also shown are a 
pivot pin 50, locking actuator 51, locking hole 64, and locking slot 63. 
FIG. 15 is a partial cross sectional view, as taken through line 15--15 of 
FIG. 14, that shows the water stabilizer assembly 41 free to move as the 
locking actuator 51 is not actuated. 
FIG. 16 is the same partial cross sectional view as presented in FIG. 15, 
and as taken through the line 16--16 of FIG. 14, that shows the locking 
actuator 51 engaged to thereby lock the water stabilizer assembly 41 in 
place. 
FIG. 17 is a partial cross sectional view, taken through line 17--17 of 
FIG. 4, of a water stabilizer assembly 41 in a lowered position but at an 
angle of attack to cause a raising of the bow. Note that in this case the 
locking actuator 51 is engaged in locking slot 63 so that there is limited 
movement of the hydrofoil 84 as indicated by rotation arrow 61. Note that 
a retractable hull member as shown as 85 in FIG's 11, 12 and 13 could be 
used instead of a hydrofoil if desired. 
FIG. 18 is a similar partial cross sectional view, taken through line 
18--18 of FIG. 4, as presented in FIG. 17 but with the water stabilizer 
assembly 41 having its hydrofoil 84 at a negative angle of attack to 
thereby create a downward moment about the bow. 
FIG. 19 is another partial cross sectional view, taken through line 19--19 
of FIG. 4 of a water stabilizer assembly 41 as retracted back up into a 
gas cushion recess 47 as is the case of the port sidehull in FIG. 4. Note 
that the locking actuator 51 is engaged into the locking hole 64 here to 
insure positive fixing of the water stabilizer assembly 41. 
FIG. 20 is a cross section, as taken through line 20--20 of FIG. 14, that 
shows an airfoil shaped strut 52. 
FIG. 21 is a cross section, as taken through line 21--21 of FIG. 14 that 
shows a cambered airfoil shaped hydrofoil 55. 
FIG. 22 is the same as presented in FIG. 22 but showing the onset of 
formation of water vapor, most commonly known as cavitation, about the aft 
end of the strut 52. This would occur at about 45 knots for most 
waterborne hydrofoil craft. 
FIG. 23 is the same as FIG. 21 but, again, showing the onset of cavitation. 
In this case it is about the hydrofoil 55 and strut 52. 
FIG. 24 is a cross sectional view, as taken through line 24--24 of FIG. 14, 
that shows a chopped strut 53 that is base vented from surface air to 
avoid cavitation damage to the strut. 
FIG. 25 presents a partial cross sectional view, as taken through line 
25--25 of FIG. 14, that shows a chopped hydrofoil 56 and chopped strut 53 
and cavitation or vapor 58 bubbles. 
FIG. 26 is a cross sectional view, as taken through line 26--26 of FIG. 14 
that shows a chopped hollow strut 54 that is base vented with gas. 
FIG. 27 presents a partial cross sectional view, as taken through line 
27--27 of FIG. 14, that shows a preferred base vented hydrofoil 57 that is 
fed gas through a hollow strut 54. The base venting concept is found to be 
best for the very high speeds, actually any speeds of over about 45 knots, 
and is especially well suited for speeds approaching the takeoff speeds of 
SeaCoaster. 
FIG. 28 is a bow view of the instant invention with optional outrigger 
hulls 82, outrigger wings 90, winglets 83, and wing caps 88. These 
enhancements allow extra lift for SeaCoaster when in the airborne mode and 
also add stability, by means of the outrigger hulls 82, when waterborne. 
FIG. 28 shows optional means of reducing beam. This is made possible by a 
complete folding up of the sidewing 91 as illustrated on its starboard 
side while the port side shows a folding of the winglet 83 only. Either 
approach is feasible while the partial folding as shown on the starboard 
side is preferred due to its simplicity and the fact that it keeps its 
outrigger hull 82 waterborne at all times for maximum transverse or roll 
stability. 
FIG. 29 presents the same bow view as FIG. 28 but with the inventive 
SeaCoaster airborne and with its hinges 89 locked. Also shown is a landing 
hull 85 in position for landing. 
FIG. 30 is a bottom plan view of the inventive SeaCoaster shown in FIG. 29. 
While the invention has been described in connection with a preferred and 
several alternative embodiments, it will be understood that there is no 
intention to thereby limit the invention. On the contrary, there is 
intended to be covered all alternatives, modifications and equivalents as 
may be included within the spirit and scope of the invention as defined by 
the appended claims, which are the sole definition of the invention.