US3481296A - Air-waterborne vessels - Google Patents

Description

Dec. 2, 1969 R. M. STEPHENS AIR'WATERBORNE VESSELS' Filed May 11, 1966 5 Sheets-Sheet, 1

INVENTOR Dec. 2, 1969 R. M. STEPHENS AIR-WATERBORNE VESSELS 5 Sheets-Sheet 2 Filed May 11, 1966 INVENTOR Dec. 2, 1969 R. M. STEPHENS AIR-WATERBORNE VESSELS Filed May 11, 1966 5 Sheets-Sheet 5 INVENTQR Dec. 2, 1969 R. M. STEPHENS 3,4

AIR-WATERBORNE VESSELS 5 Sheets-Sheet 4 Filed May 11, 1966 fig gw E E E v E NyE NTOR flG. l5

Dec. 2, 1969 R. M. STEPHENS AIRWATERBORNE VESSELS' 5 Sheets-Sheet 5 Filed May 11, 1966 fie. l4

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INVENTOR United States Patent US. Cl. 114-67 23 Claims ABSTRACT OF THE DISCLOSURE An air-waterborne vesselin which a singular volume of contained static air is contracted by the displacement of said vessel within inverted open bottom pontoons spacedly disposed catamaran fashion on either side of the hull, on the inverted bowl principle, substituting air friction for the normal wetted friction to which marine vessels are subjected, said vessel-fills the roll of a fast freighter as distinct from the tramp, steamer. Same principle is utilised in open bottom compartments on the underside ofa fully displaced cargo vessel, the air volume of said compartments being automatically maintained by the level of the water in said compartment.

In recent. years the hydrofoil and the air-cushion vehicle have come to the fore as high-speed nautical vessels. The hydrofoil uses vast amounts of power to surface and maintain essential speed, while the air-cushion vehicle of medium size is limited to light loading of some 20 lbs. to the square foot about half the weight an automobile presents. Present invention seeks to increase this loading seven to ten times.

The principle incorporated is that simply suggested by an inverted bowl on water where it weight is supported by static air slightly compressed thereby and trapped within, with a minimum of displacement. Incidentally it will be observed that the-bowl becomes highly unstable, the air escaping if the bowl is slightly tilted. It is the purpose of this invention to overcome this kind of instability, by design hereinafter outlined, more particularly as it relates to vessels solely supported above a water supporting-surface by a volume of contained static air, also to vessels which by designation will become part-displacement vessels in which a portion of the weight of the vessel is supported by contained air. It will also involve vessels fully displaced, in which the water skin friction on the bottom of the hull is replaced-by'air skin. friction. This latter group includes-.canal'and oceangoing barges.

A brief description of applicants vessel solely supported by contained static air follows, including an explanation of the principles involved.

7 Supported on long inverted catamaran type pontoons having an open bottom and straddling the vessel, its hull rides above the water without displacement other than the sidewalls of the pontoons and the gating thereto. The interior space of these pontoons extends vertically possibly the full height of the vessel or alternatively between a double floor of the vessel to a point midway of its beam. This space is partitioned transversely into a number of compartments each air-sealed from its neighbor. These transverse partitions reach down to the interior waterline, which incidentally when the vessel is fully loaded will be several feet below sea level, and at that point they terminate in a horizontally hinged flap flexibly resisting the passage of sea water. These flaps are air-sealed at the sidewalls of the pontoons so that each compartment is completedy isolated from the adjoining compartment. The stem and stern of the pontoons are flexibly gated and constructed in such a way as to keep the contained air from escaping while allowing the sea water to pass through. However to do. this effectively the lower Patented Dec. 2, 1969 gates at both stem and stern will need the assistance of coil springs, the water and air pressures at this point being more or less equal. These gates are air-sealed to the sidewalls of the pontoons by rubber sheeting either bonded or rivetted, the ends of the gates near the sidewalls are cut at an angle to allow it to swing freely with the rubber sheeting proportionately stretched. Incidentally since there might not be enough room in a canal for a barge to turn around the gates should be capable of swinging both ways from the vertical so that the barge can move in reverse direction.

An alternative to the mechanical method of gating is illustrated in FIGURE 8 and provides for water at a pressure of approximately 300 lbs. per square inch being forced downwards as a short jet sheet from superimposed tubes transversely disposed at both stem and stern of the pontoons to impinge on the next lower tube. While no precise information is available it is here assumed that any jet sheet of water would respond as any cantilever beam and deflect as the cube of the span. A single high velocity jet sheet was proposed for the Hovercraft aircushion vehicle riding on a two foot cushion of air. The proposal was later rejected as being ineffective and uneconomic in the use of water and confined the vessel to operating over water. As here proposed a series of jet sheets reduced in length to eight inches would under the cube law, experience a deflection amounting to one twentyseventh of the example cited. This arrangement of multiple jet sheets would readily yield'to the inrush of water, but with air now slightly compressed weighing 600 to 700 times lighter than sea water it is considered the contained air would be held back without loss.

It is anticipated the buoyancy compartments of vessels solely supported by contained air will be subjected to minor variations in static air pressure in a choppy sea. In order to minimze the effect of these changes, an automatic air-relief valve is located in the outer wall of each compartment to guard against undue over-pressure, while an air compressor with storage means furnishes a ready supply of air to replenish incidental air losses. However for reasons to be explained later a valve manually operated by remote control can when desired reduce the volume of air in each compartment, and should such action be taken, as might be the case with lighty loaded vessels, it will be found that the buoyancy compartments due t the pumping action of the waves will add air to its volume rather than lose it. In the interest of stability all the vessels solely supported by contained air will have water'ballast ducts in one form or another. If the ducts are located near the sea level waterline they will need to be gated to prevent or delay the loss of water therefrom should the vessel unduly tilt. In the embodiment covering a shallow draft vessel intended for up-river use and resembling the vessel illustrated in FIGURE 10 except that it would be fully and not partially gated at the ends, the principle of water ballasting is adopted in part, the pontoon itself being utilized for this purpose rather than adding a separate duct. To attain this end and to strengthen the pontoon against sand and mud bars, the bottom edges of the pontoon sidewalls are joined, and When fully gated at the ends form an enclosure suitable for the retention of water ballast. However, to avoid a buildup of air pressure within the pontoon buoyancy compartment due to the inrush of sea water therein the bottom of the pontoon is perforated in numerous places thus normalizing the interior water level, yet retaining to a modified extent the effectiveness of the ballasting principle.

In the embodiment illustrated in FIGURES 2 and 3 the water ballasting duct is shown paralleling the pontoon at the side rather than at the bottom with the object of minimising the draft. Superimposed upon this duct at the four corners of the vessel is a streamlined contained-air stabilization compartment. Together they can form a composite water ballast unit. The stabilization compartment however is supplemental and would be used when Windstorm conditions were imminent. It could if desired be omitted from the design. These stabilization compartments would be closed at the top and open into the water ballast duct but at a point well below the sea level waterline, the duct being gated. When it is desired to use these stabilization compartments they would be wholly or partially exhausted of air by vacuum means causing them to simultaneously fill with water or to the level desired. In a modification of this latter arrangement the gating could be omitted provided the duct was located along the bottom half of the pontoon. It should be pointed out however that were this duct to be without gates the water would pour out directly as the pontoon rose above the sea level waterline, at the same time draining the water from the stabilization compartment and at a time when its need was greatest. While this situation is unusual, design must be related to the worst conditions the vessel would have to meet. However it is possible that by making prior full use of the stabilization compartments the situation just described might never arise.

Should it be decided as previously suggested to dispense with the stabilization compartment and with it that arrangement of water ballast duct with which it co-operates, the alternative would be the placing of the ballast duct directly below the pontoons as illustrated in FIGURE 10. In this case the duct portion would not need to be gated at the ends because of the depth at which it was situated and would have the advantage of simplicity and added capacity. In each duct at any given moment water in the amount of 20 percent of the loaded weight of the vessel would be continuously entrained therein adding nothing to the mass of the vessel, the water being transitory and being subject to vertical inertia forces only, the only penalty, apart from the weight of metal being an increase in the wetted area subject to skin friction.

In another embodiment involving a vessel partly displaced and partly supported by air as illustrated in FIG- URE 4 the vessel has an inner and an outer buoyancy compartment both of which extend almost the full length of the vessel. The outer compartment is designed to function alternatively as a water ballast stabilization compartment but only when bad weather is imminent. The amount of water allowed in would vary with the severity of the storm. This outer compartment would be partitioned in the same way as the inner compartment, as previously described, as well as being gated at the ends. It will be recognised that in this particular form the water ballast taken in adds to the mass of the vessel as distinct from the transitory form of water ballasting previously outlined and illustrated in FIGURE 10. It should also be pointed out that the problem of admitting and ejecting water from the stabilizer compartment is very simply accomplished and with very little effort by sucking the air out of the compartments, which action simultaneously draws in the sea water to occupy the space vacated. Later by opening a valve at the top of the compartment and letting air in, the sea water will fall due to the influence of gravity. It is considered that with partly displaced ocean going vessels and the storm conditions occasionally experienced, possibly of hurricane velocity, these arrangements lend themselves admirably to the situation.

A cardinal feature of the design is the extension of the pontoon space vertically the full height of the vessel constituting itself as a buoyancy compartment. This height of air space permits a rise of water within the pontoon to a much greater extent for the same increase of loading pressure than if the space did not exist, and a marked rise of the water level within the pontoon is desirable if the spilling of the air is to be avoided. This objective, as mentioned earlier, is enhanced in the case of vessels solely supported by contained air, allowing them to settle lower in the water, by allowing some of the air now in a state of compression to be exhausted from the buoyancy compartment. However volume of buoyancy space is the criterion here not the height. According to Boyles law for gases a ten percent increase in pressure is accompanied by a reduction, amounting to one eleventh, of its original volume. Since in a selected instance we might desire a vessel loading of one pound per square inch, or 15.7 lbs. per square inch absolute, the buoyancy space will be reduced to 14.7/ 15.7 of its original volume and if the compartment was uniform in cross section and extended up for a distance of 16 feet the buoyancy space would contract approximately one foot. In addition, this rise of one foot could be increased, first by exhausting some of the air from the compartment and secondly by design enlarging the buoyancy compartment above the sea level water line. In the instance selected, a pressure of one lb. per square inch or 144 lbs. per square foot would support a column of water 2 feet 3 inches high consequently the water outside the pontoon would be that much higher than the water inside and since the water inside has already risen one foot by reason of the load compression, the water level outside would actually be 3 feet 3 inches from the bottom of the pontoon. It will be seen therefore that water entering at the stem of the pontoon will cascade down 2 feet 3 inches to the inside water level and should the vessel loading be increased to 2 lbs. per square inch or 288 lbs. per sq. ft. the water would have to cascade down 4 feet 6 inches from the outer pontoon height of 6 ft. 6 ins., the vessel having settled a further one foot with the increased compression, so that in the latter case the pontoon should be at least 7 feet deep. It will be recognised in these circumstances that all the water entering the pontoon will be depressed by an amount equal to the normal displacement of the vessel and it is natural to assume that depressing this amount of water over a mile run say would require the expenditure of considerable energy. The ultimate benefit of course would be that air friction had replaced water friction.

For obvious reasons the overwhelming majority of displacement vessels will not have buoyancy compartments located on the sides but still could benefit from a reduction of skin friction on a large portion of the wetted surface on the underside of the hull substituting air friction for water friction particularly if the beam dimension was increased relative to the draft and adapted say to medium speed tramp vessels. River barges should find this arrangement most effective. In such cases a number of rigidly or flexibly gated shallow open-bottom ducts would extend the full length of the flat bottom portion of the hull, the flexible gates being spring-loaded at both stern and stem for the containment of the static air. However in the case of ocean-going vessels these ducts would be transversely partitioned with a hinged flap at the inside waterline in much the same manner as the buoyancy compartments. These partitions would prevent most of the contained air from moving to the higher end during a pitching motion of the vessel. Some air will be lost in a rough sea but this can be replaced from a compressed air source piped into each compartment, the horizontal flexing of the partition being the means to open a valve on the air line. During storms the air supply could be cut off entirely. Existing vessels could be modified in a ship repair depot to incorporate these shallow ducts, possibly building a false keel to better support it in drydock. Shallow ducts are not expected to be as effective in the reduction of drag as the deep buoyancy compartments but their location at depth and the absence of extreme turbulence as it exists at the surface should be a factor in its favor. Skin friction at cruising speed comprises some 60 percent of the total resistance in a displacement vessel, however percent of that friction resides in the outer turbulent water boundary layer and the other 10 percent in the laminar sublayer next to the hull. This turbulence generates within the sea water a considerable momentum transfer, the visible widening extent of which increases with the speed of the ship and creates the drag upon it. It would appear that a great reduction in resistance would be effected if this momentum transfer could be strictly confined to air rather than water since in this situation the air now slightly compressed weighs one five-hundredth to one six-hundredth that of sea water. However it would seem that a minimum thickness of air cushion would be an essential criterion, to be determined empirically.

Aircraft carriers such as are built today are both large and expensive and consequently limited in numbers. Since there is every prospect that with attention now being given to the development of aircraft having V.T.O.L. (vertical-take-off-and-landing) and S.T.O.L. (short-takeotf and-landing) characteristics, that a new smaller aircraft carrier in sufficient numbers to provide wide global dispersal will be evolved. These carriers would have a shorter and relatively wider flight deck. Present application'anticipates such a vessel almost wholly. supported by air with only enough displacement to provide for efficient water propulsion, in other words a part-displacement vessel. Such a vessel would minimise all phenomena now experienced due to displacement such as the bow wave, the extensive belt of turbulence around the ship .with its consequent high drag and the eddies which fol low in'itswake. Such wave action as does occur at the bow of theproposedvessel will be confined between the sides of the hull and the side of the adjacent buoyancy compartment. The designed extra width of this aircraft carrier would be fully .utilized by buoyancy compartments which would not only supplant air friction for water friction, but would also function as lateral stabilize'rs, a downward tilt on the starboard side for instance would compress the contained air still further on that side creating additional buoyancy, while reducing the amount of buoyancy on the portside, the added leverage exerted by the buoyancy compartments in this design being a plus factor. Such a vessel could if thought necessary make use of the outer buoyancy compartment as a water ballast stabilizer .compartment as previously described and illustrated in FIGURE 4, such use however would only occur during storm conditions. The substitution of air friction for water friction over sucha large area would add considerably to its speed enabling it to run ahead of the storm should one beimpending. With regard to the utilization of the extra space provided by the enlargement of the buoyancy compartments, it is conceivable that if the increase in air pressure, which would not exceed 4 lbs. per. square inch could betolerated for long periods, the compartments could be .used as repair and service. rooms with light,heat and power provided. Perforations at the periphery of the floors would prevent interference with the buoyancy principles. A double door air-lock would allow communication between. the compartments and the rest of thevessel. A decompression room might be found necessary. I v

, Propulsion of air supported vessels is dealt with in several ways varying with the uses and the .size of the craft. A high speed vessel of rugged construction serving in the capacity of a small aircraft carrier for use of aircraft in the V.T.O.L. and S.T.O.L. categories, not havin need for large quantities of steam for catapulting operations, would have its flight deck almost clear of obstacles, having a marine engine for economical cruising and being supplemented by a number of by-pass gas turbine engines of immense power and light weight for the occasional burst of speed. With similar sized vessels in commercial operation where economy had to' be exercised both in capital expense and operating cost, a marine engine of ample proportions would provide sole propulsion.

Shown in FIGURE 3 is a pivotal engine compartment providing excellent manoeuvering capability and a shorter radius of turn, the compartment serving as a rudder. Small light vessels would most likely use air propellers much as air-cushion or ground effect machines do but in this service.

instance rudders for directional control would be hinged at the stern of the pontoons.

Vessels of the type solely supported by contained static air will be initially confined to rivers and sheltered seas and when more knowledge has been acquired as to their behavior the design of larger and more rugged craft would be undertaken. The greatest economic gain from these improvements would appear to accrue to oil tankers, grain vessels and tramp steamers on long voyages, these vessels having shallow ducts on the bottom of the hull. In the past little restraint has been exercised on the draft of these vessels. If the contentions here avowed are fully warranted, emphasis can now be placed on increasing the beam relative to the draft, since this is the area where the greatest reduction of skin friction would obtain, the wider the beam the greater the gain.

It is natural that a new type of vessel such as this is will experience problems peculiar to itself which will become more apparent at high speeds and in rough seas and must be dealt with on a trial and error basis. Most of the formulae and technology governing displacement vessels will have little place in this design and new criteria will have to be established.

The illustrations shown do not exhaust the list of possible embodiments since an interchange of elements and the combinations thus effected will be considerable and I desire only such limitation on construction as lies within the range of the principles enunciated and the scope of the appended claims.

An object of the invention is the creation of an airwaterborne vessel in which air in a static condition intervenes for support between the sea Water and said vessel to avoid the immergence of said vessel.

An additional object is to substitute air friction for water friction wherever possible in the support of airwaterborne vessels thereby increasing the speed for the same expenditure of energy.

A further object is to increase the relative loading of air-waterborne vessels to reduce their cost of operation. A further object is to institute a fast marine cargo Another object is to effect economy in the amount of air used in the support of air-waterborne vessels.

Another object is to reduce the amount of skin friction resistance of displacement vessels by increasing the amount of horizontal support surface relative to the vertical surface, Within the limit of stability and other pertinent considerations by the intervention of air between the water supporting surface and the horizontal surface of the vessel.

A further object is the aquisition by air-waterborne vessels of the benefit of water ballasting without adding same to the mass of the vessel.

Another object is the reduction by mechanically flexed gating as well as by hydraulic gating, the impact ofthe sea water on air-waterborne vessels when in motion and the retention of contained static air by such means.

A further object is the elimination of the undesirable yaw movement of vessels supported solely by contained static air.

Another object is the elimination of the accretion of barnacles to the underside portion of the hull of a marine vessel by the intervention of air between the water supporting surface and the bottom of the hull withthere- 'sulting reduction of drag on the ship and the recurring need for drydocking facilities.

Embodiments of the invention will be described with reference to the accompanying diagrammatic drawings in which:

FIGURE 1 is a cross-sectional side elevation of a lightdraft vessel with the outer panelling removed to show the bulkheads.

FIGURE 2 is a plan view of the same vessel showing the cut-away line and direction for the view in FIGURE 1.

FIGURE 3 is a front view of the same vessel with the bottom edge of the pontoon unit being joined, also the positioning of the pivotal engine compartment.

FIGURE 4 is a cross-sectional view amidship of a partdisplacement vessel looking toward the stern showing the water ballast and stabilization compartment contiguously arranged and with the buoyancy compartment containedair area indicated by the relative water levels, also the extension of this buoyancy area horizontally above the deck of the vessel.

FIGURE is an enlarged cross-sectional broken view bottom edge of the pontoon unit being joined, also the gating of the lower end of a bulkhead.

FIGURE 6 is a front view of the stem gating in FIG. 5.

FIGURE 7 is an interior view of the stern gating of a buoyancy compartment looking towards the stem from the second last bulkhead of the vessel in FIGURE 1.

FIGURE 8 is a cross-sectional view of an alternative hydraulic method of stem gating.

FIGURE 9 is a cross-sectional view of the stem gating of a light-draft river vessel or barge.

FIGURE is an alternative arrangement to FIG. 1 eliminating the stabilization compartment and positioning the open ended water ballast duct beneath the pontoon buoyancy unit.

FIGURE 11 is a fragmental view of an alternative method of mechanical gating showing spring-loaded freely hinged gates at stem of pontoon.

FIGURE 12 is a cross section of compositely constructed tube for hydraulic method of gating.

FIGURE 13 is a cross section plan view of the hydraulic tube.

FIGURE 14 is a plan view, looking up, of the ducting on the underside of the hull of a barge or displacement vessel.

FIGURE is a broken cross-sectional side view of the shallow ducts of the vessel in FIGURE 14.

FIGURE 16 is a detail of the flap activating mechanism of the air line valve of the vessel shown in FIGURES 14 and 15.

The embodiment illustrated in FIGURE 1 shows the hull 1 streamlined and elevated above the sea-level waterline and spanning inverted catamaran type pontoons 2. The pontoon air space extends vertically the full height of the vessel to create an enlarged buoyancy space which is subdivided by bulkhead or partitions 3 into compartments 4 each air-sealed from its neighbor. The partitions 3 extend down almost to the interior waterline where they terminate in a flexed flap 5 air-sealed by rubber sheeting 6 to the sidewalls 7 of the pontoons 2 and extend down below the said interior waterline to complete the air-sealing of the buoyancy compartments 4.

With the object of maintaining the air pressure within the buoyancy compartments 4 at a desired level, each compartment 4 has a simple automatic over-pressure relief valve (not shown) on its outer wall, the wall being eliminated by the cut-off in FIGURE 1, also a valve (not shown) on its inner wall remotely controlled and linked to an air compressor source for the replenishment of incidental air losses, also a series of air ducts 8 of small dimension linking the opposite number compartments 4 as disposed about the major and minor axes of the vessel. This air duct system 8 is specially designed for vessels of light draft and is intended to provide an automatic fourpoint equalization of air pressure in any four buoyancy compartments 4; excessive over-pressure being relieved by the relief valve previously mentioned. FIGURE 1 also shows the location of the gates 9 at the stem of the pontoon 2 also shown in greater detail in FIGURES 5 and 6. Designed to reduce the impact of the sea water on the pontoons 2 this series of inclined superimposed gates 9 flexibly hinged at 10 are air-sealed by rubber sheeting 6 in the same manner as the flexed flap 5 at the lower end of the partitions 3. However in this instance a rubber buffer 11 at the bottom of the gate '9 bears against the next lower hinge 10 to seal the gates 9 against air loss when shut by internal air pressure. These gates 9 are flexed to the horizontal position during the rapid inrush of sea water as the vessel is propelled forward. The lower of the gates 9 are tension spring-loaded since in the stationary condition the air and water pressures are substantially in balance at this point and the assistance of springs 12 is needed to make their action positive. A single gate 13 hinged at the stern of the pontoon 2 at a point above the interior waterline has its upward movement resisted by springs 12. FIGURE 6 shows a front view of the gates '9' in a slightly open position, the diagonal cut of the gates 9 is seen allowingthe rubber sheeting 6' to fully flex and evenly stretch without obstructing the movement of the gate 9 to the horizontal position. When the water is not passing through the gates 9 the interior air pressure keeps them shut. In FIGURE 7, an interior view, shows coil springs 12 secured to the stem gate 13 capable of exerting strong pressure against the sea flow and static air pressure which at this point are additive. In this case the bottom of the stern gate 13 terminates well below the interior waterline. A modified form of mechanical gating is illustrated in FIGURE 11 and shows a freely hinged flap 14 unsealed except when shut impinging against a rubber buffer 15 bonded or rivetted to the sidewalls 7 of the pontoons 2 and the next lower hinge 10, and having the advantage of simplicity in form and in action but with increased risk of air loss.

An alternative to the mechanical method of gating is illustrated in FIGURE 8 and shows a series of vertically spaced tubes 16 spanning the sidewalls 7 of the pontoon 2. A thin jet sheet of water is discharged from the underside of the tube 16 to impinge on the upper rounded surface of the next lower tube 16. These tubes 16 are shown in more detail in FIGURES 12 and 13, preferably streamlined and of composite construction in order that the slit 17 on the underside of the tube 16 be continuous. Internal braces 18 join the lips of the slit 17 to give it the necessary strength to resist the great pressure within. A series of deflectors 19 staggered within the tubes 16 change the direction of the hydraulic flow through degrees to issue at the slit 17 as a thin jet sheet.

Water ballast forms an integral part of a number of the embodiments illustrated, varying in position and relative size in accordance with the extent of the need and the territorial area in which the vessel operates. Excluded from the category are fully displaced vessels as well as barges.

FIGURE 2, which should be studied in conjunction with FIGURE 3 is a plan view of the vessel in FIGURE 1. FIGURE 2 shows a water ballast duct 20 adjoining the pontoon 2 on the outside and extending its 'full length. Four stabilization compartments 21, one at each corner of the vessel are superimposed upon the water ballast duct 20, the two structurally forming a composite unit. However, the duct portion 20 functions continuously while the stabilization compartment 21 operates only on a supplemental basis. The submersed portion of the stabilization compartment 21 is streamlined and not open directly to the sea flow, this latter function being restricted to the ballast duct portion 20. It will be observed that this lower duct 20 is gated at both stem and stern with the object of retaining the water ballast should the pontoon 2 be unduly elevated above the sea level which action should not be confused with the normal roll of the ship. Stem gates 9 and stern gates 13 do not interfere with the transitory nature of the ballast flow until such time as this undue tilting occurs, thus creating a vectored inertial component. The bottom edges of the pontoon 2 of this embodiment are joined for added strength and this arrangement makes it mandatory, since the pontoon 2 is gated, to perforate the bottom surface of the pontoon 2 in numerous places in order to keep the interior water down to its nominal level. A small dimension air duct 22 links all four stabilizer compart- 9 ments 21 with a vacuum source (not shown) but which may be the inlet of the air compressor.

In FIGURE 4, a part displacement vessel, extended use by necessity is made of the air buoyancy facilities not only providing additional support but added leverage. The outer buoyancy compartment 4 serves on occasion as a supplementary stabilization compartment 21 since as an ocean-going vessel it may be called upon to meet very severe storm conditions. In such situations the air is sucked out of the compartment 4 replacing it simultaneously with sea water and so functioning as compartment 21. However it is quite probable that under ordinary rough weather conditions reliance will be placed on the added leverage of the outer compartment 4'functioning in the interest of buoyancy to furnish all the additional stability required. In FIGURE 4 the buoyancy compartment 4 is shown extending over the deck of the vessel, however this extension must terminate amidships otherwise its ability to vfunction as a stabilizing factor will be negated. These buoyancy extensions could, if used, be intermittently spaced between deck hatches or oil inlet valvesin the case of oil tankers.

In FIGURE 10 the water ballast duct is set immediately below the pontoon 2 portion of the buoyancy compartment, no diaphragm separates them. This particular embodiment is designed to operate in sheltered seas where anabs'ense of draft limitation such as would be necessary with up-river craft, contributes favorably to the design. The greater depth at which the ballast duct 20 is set in this case eliminates the need to downwardly extend the stem gates 9 and the stern gates 13 to cover the ballast duct 20. The free flow of water through'the duct 20 thus permitted, avoids the water and air pressure build-up which would occur if the ballast duct 20 were gated. Perforating the bottom of the ballast duct 20 to normalize the pressure situation within the pontoon 2 is thus obviated.

The embodiment shown in FIGURE '14 has for its object the replacing of water skin friction with air skin friction. The drawing shows a series of shallow longitudinal open bottom ducts 23 extending the length of the fiat bottom portion of the hull 1. Rigid transverse walls 24 angularly disposed to the sea water flow at both stem and stern are air-sealed secured to the hull 1 and sidewalls 25 of the air ducts 23 to ensure the containment of the air within the duct 23, said ducts being subdivided into a multiplicity of air-sealed compartments 26 by transverse partitions 27 secured to the bottom of the hull 1 and the sidewalls 25 and terminating in a flap 28 backwardly hinged at'a point above and extending below theinterior waterline to complete the air-sealing of each compartment 26. The purpose of the partition 27 is to prevent the mobility of the air contained within the duct 23 during a pitching motion of the vessel. Each compartment 26 has valved communication with an exterior compressed air source for the replenishment of incidental air losses..Air loss when of. consequence causes the sea water to rise higher withinthe duct 23with the result that the flap 28 will be flexed tothe horizontal by the sea water flow and in doing so activates a springloaded valve 29 on the airline to admit compressed air into the compartment 26 to make good the air loss. The compressed air must be initially admitted to the compartments 26 at a greater pressure than the static pressure existing at the depth at which the ducts 23 are positioned. At a depth of 10 feet in salt water the air will be compressed approximately 23'percent; at 20 feet, 38 percent; and at 30 feet, 47 percent; the air being admitted to some desired level between the hinge of the flap 28 and the bottom of the duct 23.

What is claimed is:

1. An air-waterborne vessel supported above water solely by contained static air which is contained above a water surface and within the sealed envelope of longitudinally disposed open bottom ducts, their lower ex 10 tremity penetrating said water surface to form an enclosure on either side of the hull of said vessel, said ducts being gated at stem and stem to permit a one-way flow of seat water therethrough while preventing the escape of, said contained air therefrom, said ducts being subdividedinto segregated buoyancy compartments by vertical partitions, said longitudinal ducts sustaining said hull above the sea level waterline to avoid displacement of said hull, said longitudinal ducts functioning as inverted catamaran type pontoons, said partitions terminating at said water surface by a horizontally disposed flap flexibly secured and responsive to the sea flow to complete. the segregation of the said buoyancy compartments, said.

ducts having parallel sidewalls and having a gate at the stem end spanning said sidewalls and being flexibly air-sealed thereto, said gate being horizontally hinged above the sea level waterline and extending above and below said waterline, said gates at stem and stem being designed to prevent the escape of said contained static air while permitting a one-way flow of sea water thereunder, said buoyancy compartments supporting the hull of said vessel above said water surface to avoid displacement of said hull.

2. An air-waterborne vessel as described in claim 1, said pontoons having parallel sidewalls and being gated at both stern and stern, said gating at the stem comprising a series of superimposed horizontally hinged flaps spanning said sidewalls and being flexibly air-sealed thereto and contact sealed when closed under pressure against the next lower hinge, said series of superimposed flaps extending from a point above the sea level waterline to a point below the pontoon interior waterline, said gating at the stern comprising a spring loaded flap vertically pivotal about a horizontal axis and spanning .said pontoon sidewalls and being hinged above and extending below said pontoon interior waterline, said gates at stem and stern designed to prevent the escape of said contained static air while permitting a one way flow of sea water therethrough and thereunder, said buoyancy compartments supporting the hull of said vessel above the water supporting-surface to avoid displacement of said the sidewalls of said pontoon buoyancy compartments being joined at the bottom, said pontoons having a multiplicity of perforations on its bottom surface below said pontoon interior waterline with the object of maintaining said interior waterline at its norm.

5. An air-waterborne vessel as described in claim 4, means contributing to the stability of said vessel, said means entailing the release of at least ten percent of the air from within said contained static air space.

6. A vessel as described in claim 5, having means for the replenishment of incidental air losses, said means comprising air compression and storage means with ducted valved communication manually operated by remote control to each said buoyancy compartment independently, each said compartment having a valved vent remotely controlled permitting the release of a measured quantity of said contained static air, and an over-pressure relief valve automatically activated.

7. A vessel as described in claim 6, each said pontoon buoyancy compartment having freely transmitted air ducted communication with the buoyancy compartment oppositely disposed about both major and minor axes of said vessel for the purpose of equalizing air pressures laterally and longitudinally to assist in the preservation of overall stability.

8. A vessel as described in claim 7, having transitory water ballast means associated therewith and disposed on both sides of said vessel.

9. A vessel as described in claim 8, said transitory water ballast means comprising a longitudinal duct contiguously disposed below each said pontoon and forming a composite unit therewith, said duct portion being open at the top and ends and closed at the bottom.

10. A vessel as described in claim 9, said transitory Water ballast means comprising longitudinal ducts contiguously adjoining said pontoon buoyancy compartments on the side and positioned below the sea level waterline, said ducts having horizontally hinged transversely disposed gates at stem and stem limited in the amount of their downward swing by a stop-rail, the upward swing of the gate at the stern being spring resisted to retain said water ballast within said duct when elevated above sea level.

11. A vessel as described in claim 10, having stabilization compartments vertically disposed above and below the sea level waterline, closed at the top and open at the bottom and being located one at each outer corner of said vessel, means to exhaust the air and means to release the water from said stabilizer compartments, said compartments communicating vertically with said water ballast.

12. A vessel as described in claim 11, having propulsion means integral therewith, said propulsion being derived by air thrust while at sea and by water thrust while in port, means to surface said water thrust means and means associated with said vessel and said water supporting-surface to directionally control the movement of said vessel.

13. A vessel as described in claim 12, the primary means of propulsion operating in a water media supplemented on an intermittent basis by the air thrust of gas turbines.

14. A self-propelled air-waterborne vessel as described in claim 13, said water thrust means being contained within a streamlined compartment extending below the hull of said vessel and being partly submersed, said submersed portion of said compartment having means associated therewith for the directional control of said vessel.

15. A vessel as described in claim 14, said streamlined engine compartment being horizontally pivotal about a vertical axis, said submersed portion of said pivotal compartment functioning when necessary, as a rudder.

16. An air-waterborne vessel supported at sea partly by contained static air and partly by displacement of said hull, having propulsion means integral therewith, said static air contained above a water surface and within a pair of longitudinally disposed buoyancy units having sidewalls, and being closed at the top open at the bottom, gated at the ends and straddling the hull of said vessel, said buoyancy units being subdivided into compartments by transverse vertically disposed bulkheads, each said compartment being air-sealed from the adjoining compartment, said bulkheads terminating at the buoyancy unit interior waterline in a horizontally hinged flap flexibly air-sealed to said sidewalls to complete the air-sealing of said compartments, said gating at both ends of said buoyancy unit being designed to prevent the escape of said contained static air while permitting a one-way flow of sea water therethrough.

17. A part displacement vessel as described in claim 16, said buoyancy compartments having in addition a horizontal partition serving as a floor, said floor having a multiplicity of perforations at the periphery, an airlock having air-sealed doors at each end of said airlock communicating with and separating said buoyancy compartments from the rest of the vessel, means to prevent both air-lock doors being opened at the same time, signal means associated with said door opening operation and means to provide heat, light and power to said buoyancy units.

series of superimposed horizontally hinged flaps spanning said sidewalls and being flexibly air-sealed thereto and contact sealed when closed under pressure against the next lower hinge, .said series of superimposed flaps at the stem extending from a point above the sea level waterline to a point below said buoyancy unit interior waterline and at the stern said series of superimposed gates-ex'-' tending above and below said buoyancy unit interior waterline, the lower of all saidgates being spring loaded-* for the positive containment of said static air. g

20. A vessel as described in claim 19, the gatingat the stern of said buoyancy unit comprising a single hori zontally pivotal spring loaded flap spanning the sidewalls of said buoyancy unit and being flexibly air-sealed there-- below said to, 'said fiap being hinged above and extendingv buoyancy unit interior waterline. 1 i

21. A vessel as described in claim 20, having transitory water ballasting means associated therewith-comprising longitudinal open ended ducts positioned below sea level on either side of said hull.

22. A vessel as described in claim 21, said water ballast means comprising a supplementary compartment contiguously paralleling said buoyancy unit above and below the sea level waterline, said supplementary compartment being closed at the top, open at the bottom, gated at the ends and subdivided by vertical partitions terminating at.

a point normal to the buoyancy unit interior waterline, means to add and means to withdraw air from said subdivided supplementary compartment such that it may a function at will as a buoyancy unit in good weather and as a water ballast compartment in bad weather, means automatically recording the level of water ballast in said compartments.

23. A marine vessel having a fully displaced hull at sea and being substantially fiat bottomed, a means for substituting air skin friction for water skin friction comprising contiguous longitudinal open bottom ducts having parallel spaced vertical walls disposed on the underside of said hull and intersecting the water surface, said walls being spanned at intervals by transverse partitions inclined to the sea flow to form a series of open bottom compartments containing air in a static condition, said transverse partitions being rigidly secured to said hull and terminating at the water level, within said ducts, in a spring loaded flap capable of flexing to the horizontal under the pressure of sea water flow, a source of compressed air communicating with said compartments, valve means for said compressed air operatively connected with said spring loaded flap and operating by the flexing of said flap to replenish air losses within said compartments.

References Cited UNITED STATES 'PATENTS 1,621,625 3/1927 Casey. 1,819,216 8/1931 Warner. 3,146,752 9/1964 Ford. 3,198,274 8/1965 Cocksedge. 3,288,236 11/ 1966 Padial.

FOREIGN PATENTS 232,436 12/1959 Australia.

ANDREW H. FARRELL, Primary Examiner U.S. Cl. X.R.

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