US3511204A

US3511204A - Method and apparatus for steering twin hulled vessels

Info

Publication number: US3511204A
Application number: US779349A
Authority: US
Inventors: Edward Gunston Tattersall
Original assignee: Hovermarine Ltd
Current assignee: Hovermarine Ltd
Priority date: 1967-12-23
Filing date: 1968-11-27
Publication date: 1970-05-12
Anticipated expiration: 1987-05-12
Also published as: GB1212380A; DE6812634U

Description

May 12, 1976 E. G. TATTERSALL 3,511,204

METHOD AND APPARATUS FOR STEERING TWIN HULLED VESSELS Filed Nov. 27, 1968 2 Sheets-Sheet L FIG] BY W

y 1970 E. G. TATTERSALL 3,511,204

METHOD AND APPARATUS FOR STEERING TWIN HULL-ED VESSELS Filed Nov. 27, 1968 2 Sheets-Sheet 2 FIG] ,W- 3? A. I1 Y Q 1 20 20 1/ 23 Wgm 7M 3r W United States Patent O 3,511,204 METHOD AND APPARATUS FOR STEERING TWIN HULLED VESSELS Edward Gunston Tattersall, Hythe, Southampton, England, assignor to Hovermarine Limited, London, England, a corporation of the United Kingdom Continuation-impart of application Ser. No. 672,067,

Oct. 2, 1967. This application Nov. 27, 1968, Ser.

No. 779,349 Claims priority, application Great Britain, Dec. 23, 1967, 58,571/ 67 Int. Cl. B63h 25/06 US. Cl. 114-163 13 Claims ABSTRACT OF THE DISCLOSURE A twin-hulled marine craft, for example, a sidewall air-cushion craft, is steered by a pair of rudders, one rudder disposed beneath each hull. The rudders are inclined outwardly so that when the craft executes a turn a force couple is generated which tends to bank the craft into the turn.

This is a continuation-in-part application of application Ser. No. 672,067, filed Oct. 2, 1967, now abandoned.

This invention relates to methods of apparatus for steering twin-hulled marine craft.

Application Ser. No. 672,067 disclosed a twin-hulled marine craft having a plurality of control surfaces in the form of rudders disposed laterally beneath the hulls of the craft in a symmetrical arrangement, each of the surfaces being disposed in a plane inclined to the vertical.

The invention disclosed by application Ser. No. 672,067 has particular application to a sidewall gas-cushion craft or vehicle, that is to say, to a vehicle for travelling over water and which, in operation, is supported above the water by a cushion of compressed gas, for example, air formed between the vehicle body and the surface of the water. The sides of the vehicle-supporting cushion are contained by a pair of longitudinal hull structures or sidewalls extending lengthwise along the sides of the vehicle body and depending therefrom to dip into the water and effect a cushion seal. In this application the control surfaces comprise a pair of rudders, each rudder being disposed beneath a sidewall.

According to one aspect of the invention, a marine craft is provided with craft steering means comprising a pair of steering control members mounted beneath the craft so as to be symmetrical with respect to the longitudinal axis of the craft and so as to be disposed in planes inclined to the vertical, and means for pivoting each control surface about a substantially vertical axis.

According to another aspect of the invention, a marine craft comprises a pair of laterally-spaced hull structures, each hull structure having inner and outer side surfaces and a bottom surface wherein the inner surface extends downwardly below the outer side surface, and the bottom surface presents a downwardly and inwardly sloping face and means for steering the craft, said means comprising a steering control member mounted beneath each hull structure in a plane inclined to the vertical whereby the inclined planes intersect at a point above the control members so as to include an acute angle therebetween.

The craft may further comprise a pair of longitudinal hull structures spaced apart by a central body structure, wherein the steering control members are disposed beneath the hull structures and are pivoted by shafts extending upwardly through the hull structures.

The craft may be provided with means for forming a craft-supporting cushion of pressurised gas beneath the body structure, the sides of said cushion being contained by the hull structures. The craft then comprises a sidewall gas-cushion vehicle.

An embodiment of the invention according to its various aspects will now be described by way of example with reference to the accompanying drawings wherein:

FIG. 1 is a side view of a sidewall gas-cushion vehicle,

FIG. 2 is a rear view of part of the vehicle and to a slightly enlarged scale,

FIG. 3 is another rear view of the vehicle, this time in broken form and to a further enlarged scale,

FIG. 4 is a diagrammatic rear-end view of the vehicle and illustrates the forces created by the steering control members,

FIG. 5 is a view generally similar to FIG. 4 but illustrating a different form of sidewall of the vehicle, and

FIGS. 6 and 7 are diagrammatic plan views of the rear end of the vehicle and illustrate the steering control members in both neutral and steering positions.

With reference to FIG. 1 to 3, a sidewall gas-cushion vehicle 1 travels over a water surface 2 and is supported thereover by a cushion 3 (not FIG. 1) of pressurised air formed between the vehicle body 4 and the water 2. The sides of the vehicle-supporting air-cushion 3 are contained by a spaced pair of longitudinal hulls or sidewalls 5 of solid construction extending lengthwise along the sides of the vehicle body 4 and depending therefrom to dip into the Water 2 and effect a seal. The bow end of the cushion 3 is contained by a multi-part flexible wall or skirt 6 and the rear end thereof by a one-piece flexible skirt in the form of an inflated bag 7.

The air forming the cushion 3 is drawn in from the atmosphere, through side intakes 8, by a compressor 9 driven by a variablespeed engine 10. The pressurised air is discharged to the space (the cushion space) occupied by the cushion 3 by a duct 11 and the bag 7 is inflated by air tapped off the duct 11 by a duct 12. The vehicle 1 is propelled by water-screw propellers 13 rotated by inclined shafts 14 located in the sidewalls 5. The shafts are driven by variable-speed engine and gearbox units 15. The vehicle 1 is steered by a pair of control surfaces or rudders arranged to work in unison. Each rudder 20 is of tapered section and is disposed laterally beneath the vehicle in a substantially symmetrical arrangement, the upper parts of each of the rudders 20 being inclined at about Lo. between 55 and about a substantially horizontal axis 21 extending in a direction substantially parallel to the longitudinal axis 27 FIGS. 2 and 3, only) of the vehicle. Thus, each rudder 20 is disposed in a plane inclined to the vertical. Each rudder 20 is pivoted about a substantially vertical axis 25. The inclined planes of the rudders 20 intersect at a point well above the rudders 20 and together define an acute angle.

Each rudder 20 is pivoted about its axis 25 by a shaft 23 which is bent at a point adjacent the upper edge of the nudder 20 so that it penetrates the bottom edge of the associated sidewall 5 to extend upwardly therefrom in a substantially vertical direction where it connects with electrically-operated tiller apparatus 24 under the control, through electrical signal lines (not shown), of the pilot of the vehicle.

The axes of the shafts 23 thus change in direction from lying in the places of the rudders 20 at points adjacent the rudders 23 to being coaxial with the axes 25. Accordingly, although the rudders 20 are inclined downwardly and outwardly at the required angles, the major parts of the shafts 23 extend upwardly through the sidewalls 5 with a mainly vertical component of direction.

The arrangement demands the provision of only one seal (the seal 26 of FIG. 3) for each shaft 23 and allows the tiller apparatus 24 to be disposed immediately above the sidewalls 5 and in outboard positions where they are not inconveniently placed.

With reference to FIG. 4, the inclined rudder arrangement results in the creation of horizontal (X) and vertical (Y) components of force which act in opposite directions and thereby set up a couple Y.d about the central longitudinal axis 27 of the vehicle 1, d being the lateral distance separating the rudders 20. This couple acts, when the vehicle executes a turn to starboard, as indicated by the arrow 30, to bank the vehicle into the turn. This banking effect is a desirable control feature. The hull structure side force exerted on the water is indicated by the arrows 36.

In the arrangement shown in FIG. 5, each hull structure has inner and

outer side surfaces

31, 32 disposed substantially parallel to each other. The inner side surface 31 of the hull structure 5 extends downwardly below the outer side surface 32 thereof. Each hull structure 5 also has a bottom surface 33 the whole of which presents a downwardly and inwardly sloping face (disposed at substantially 45 to the horizontal) extending between the lower edges of the inner and

outer side surfaces

31, 32.

In operation, as the craft banks in during a turn, water pressure acting normal to the inclined bottom surface 33 of the upgoing hull structure 5, as indicated by the arrows 34, assists the banking in moment by an upward component of thrust. Water pressure does not generate a significant upward component of thrust on the downgoing hull structure 5 due to the turbulence created by sideslip of the craft.

If desired, the knife-edges defined by the

converging surfaces

31 and 33 can be cut back at the horizontal lines indicated at 35 so that the bottom surfaces 33 each presents an inner, horizontal face as well as an outer downwardly and inwardly sloping face. This modification eases the problem of sealing the propeller shafts 14 (FIG. 1) to the hulls 5.

FIGS. 6 and 7 show, respectively, the relative positions of the rudders 23 in the neutral (FIG. 6) position and when the vehicle 1 is turning to .port (FIG. 7), as indicated by the arrow 30.

As shown in FIG. 3, the inner and outer side surfaces of a hull structure 5 may converge slightly in a downward direction.

I claim:

1. A marine craft provided with craft steering means comprising a pair of steering control members mounted beneath the craft so as to be symmetrical with respect to the longitudinal axis of the craft and so to be disposed in planes inclined to the vertical, and means for pivoting each control member about a substantially vertical axis.

2. A craft as claimed in claim 1 comprising a pair of longitudinal hull structures spaced apart by a central body structure wherein the steering control members are disposed beneath the hull structures and wherein said means for pivoting the control members comprise shafts extending upwardly through the hull structures.

3. A craft as claimed in claim I provided with means for forming a craft-supporting cushion of pressurised gas beneath the body structure, the sides of said cushion being contained by the hull structures.

4. A craft as claimed in claim 3 wherein the control members are respectively disposed in planes whereby the upper parts of the control members are disposed at about 60 to the vertical.

5. A craft as claimed in claim 2 wherein each hull structure has inner and outer side surfaces and a bottom surface, the inner side surface extending downwardly below the outer side surface and the bottom surface presenting a downwardly and inwardly sloping face.

6. A craft as claimed in claim 5 wherein each bottom surface presents a horizontal face as well as a sloping face.

7. A craft as claimed in claim 5 wherein the whole of each of said bottom surfaces is disposed at substantially 4 45 to the horizontal.

8. A craft as claimed in claim 5 wherein the inner and outer side surfaces are disposed substantially parallel to each other.

9. A marine craft comprising a pair of laterally-spaced hull structures, each hull structure having inner and outer side sufaces and a bottom surface wherein the inner surface extends downwardly below the outer side surface, and the bottom surface presents a downwardly and inwardly sloping face and means for steering the craft, said means comprising a steering control member mounted beneath each hull structure in a plane inclined to the vertical whereby the inclined planes of the control members intersect at a point above the control members so as to include an acute angle therebetween.

10. A marine craft as claimed in claim 9 provided with a central body structure extending between the hull structures and with means for forming a craft-supporting cushion of pressurised gas beneath the central body structure, the sides of said cushion being contained by the hull structures.

11. A method of steering a twin-hulled marine craft comprising mounting a rudder control surface beneath each hull structure of the craft, the control surfaces being disposed laterally in a symmetrical arrangement beneath the craft, wherein the control surfaces disposed respectively on each side of the central fore and aft axis of the craft are respectively disposed in planes inclined to the vertical whereby the respective planes intersect one another above the level of the control surfaces so as to include an acute angle therebetween, and causing pivotal deflection of the control surfaces about subtantially vertical axes so as to turn the craft and so as to produce a vertical couple acting about the central fore and aft axis of the craft whereby, when executing the turn, the craft is banked into the turn.

12. A marine craft as claimed in claim 9 wherein each bottom surface presents a horizontal face a well as a downwardly and inwardly sloping face.

13. A marine craft comprising a pair of longitudinal hull structures spaced apart by a central body structure, craft steering means comprising a pair of rudders mounted beneath the craft so as to be symmetrical with respect to the longitudinal axis of the craft and so as to be disposed in planes inclined to the vertical, whereby the inclined planes of the rudders intersect at a point above the rudders so as to include an acute angle therebetween, means for pivoting each rudder about a substantially vertical axis and including shaft members extending upwardly through the hull structures, means for forming a craft supporting cushion of pressurised gas beneath the body structure, front and rear flexible skirt means extending between the front and rear ends of the hull structures respectively so as to contain the front and rear ends of said cushion, said rear flexible skirt means being of hollow, inflatable construction, means for supplying inflation gas to said rear flexible skirt means from within the craft, and craft propulsion means carried by the hull structures, each hull structure having an outer surface, an inner surface which extends downwardly below the outer surface and a bottom surface which extends downwardly and inwardly from the outer surface and then horizontally and inwardly to the inner surface.

References Cited UNITED STATES PATENTS 360,488 4/1887 Sweeney 114-163 344,679 6/1886 Thornycroft 1l4-l63 2,263,529 11/1941 Dow 114-163 ANDREW H. FARRELL, Primary Examiner