Amphibious catamaran

Abstract

An amphibious catamaran is characterised by the inclusion of two spaced apart hulls ( 1,2 ); a framework ( 3 ) supporting the hulls; a motor ( 14 ) supported by the framework; a drive unit ( 21 ) for water propulsion actuated by the motor ( 14 ) in use; at least ( 3 ) land wheels such as ( 40 - 44 ); two sub-frames ( 44, 45 ), each supporting one or more land wheels ( 40 - 44 ); height adjustment means ( 46; 47 ) enabling in use one sub-frame, and preferably both sub-frames ( 44, 45 ), to be moved with respect to the framework ( 3 ) from a position where the land wheels ( 40 - 44 ) stably support the catamaran for travel on land, with the hulls ( 1, 2 ) clear of the land, and a position where those of the land wheels ( 40 - 44 ) associated with the moveable sub-frame are raised upwardly above the bottoms of the hulls ( 1, 2 ); drive means (not shown but including motor ( 14 )) for land propulsion coacting with one or more of said land wheels ( 40 - 44 ); steering means (not shown) for steering the craft on water and on land; and an input station ( 59 ) for any person who is to operate the craft on water or on land, or for receiving remote signals to control the operation in use, or both purposes.

1 . An amphibious catamaran characterised in including: 
 two spaced apart hulls;    a framework supporting the hulls;    a motor supported by the framework;    a drive unit for water propulsion actuated by the motor in use;    at least 3 land wheels;    two sub-frames, each supporting one or more land wheels;    height adjustment means enabling in use one of the sub-frames to be moved with respect to the framework from a position where the land wheels stably support the catamaran for travel on land, with the hulls clear of the land, and a position where its associated land wheels are raised upwardly above the bottoms of the hulls;    is drive means for land propulsion coacting with one or more of said land wheels;    steering means for steering the craft on water and on land;    and an input station for any person who is to operate the craft on water or on land, or for receiving remote signals to control the operation in use, or both purposes.    
     
     
         2 . An amphibious catamaran as claimed in  claim 1  wherein a front or leading sub-frame is pivoted at its rear to the framework and a rear or trailing sub-frame is pivoted at its front to the framework both sub-frames being so pivoted for pivotal movement about substantially horizontal, substantially parallel axes in use which are substantially perpendicular to the straight-ahead line of travel of the craft.  
     
     
         3 . An amphibious catamaran as claimed in  claim 2  wherein the height adjustment means enables each sub-frame to be positioned in at least 3 positions namely: 
 a fully raised position  
 a fully lowered position  
 an intermediate position where the hulls clear land by substantially the minimum amount needed for safe on-road travel.  
 
     
     
         4 . An amphibious catamaran as claimed in  claim 3  wherein the height adjustment means enables the front and rear sub-frames and associated land wheels to be totally raised above the bottoms of the hulls in use.  
     
     
         5 . An amphibious catamaran as claimed in any one of  claims 1  to  4  wherein the height adjustment means include pneumatic and/or hydraulic rams.  
     
     
         6 . An amphibious catamaran as claimed in  claim 5  wherein the height adjustment means include double-acting hydraulic rams.  
     
     
         7 . An amphibious catamaran as claimed in  claim 6  wherein a hydraulic circuit supplying the hydraulic rams includes at least one sealed-gas spring to provide resilience in the suspension of the framework on the land wheels.  
     
     
         8 . An amphibious catamaran as claimed in  claim 6  wherein a hydraulic circuit supplying the hydraulic rams includes multiple, sealed-gas springs at least some of which are selectable to enable choice of resilience in the suspension of the framework on the land wheels.  
     
     
         9 . An amphibious catamaran as claimed in any one of the preceding claims wherein the drive unit is a propeller and the propeller is supported by depth control means, said depth control means enabling the height or depth of the propeller with respect to the hulls to be quickly adjusted to exploit the available depth of water, if any.  
     
     
         10 . An amphibious catamaran as claimed in  claim 9  wherein the depth control means is a parallelogram linkage adapted to maintain the trim of the propeller at any selected depth.  
     
     
         11 . An amphibious catamaran as claimed in  claim 10  wherein the top and/or bottom arms of the parallelogram linkage are adjustable in length to alter the trim of the propeller.  
     
     
         12 . An amphibious catamaran as claimed in  claim 11  wherein the top and/or bottom arms comprise or incorporate double-acting pneumatic or hydraulic rams to effect length adjustment.  
     
     
         13 . An amphibious catamaran as claimed in any one of  claims 9  to  12  wherein the propeller is hydraulically driven, in use, via a usually unsubmerged hydraulic motor driving a substantially vertical partially submerged shaft which drives the propeller via a submerged pair of bevel gears, in use.  
     
     
         14 . An amphibious catamaran as claimed in any of  claims 9  to  13  wherein a propeller shroud is able to be lowered close to the top of the propeller by shroud control means, or raised away, to suit water conditions, to increase propeller thrust.  
     
     
         15 . An amphibious catamaran as claimed in any one of the preceding claims wherein the hulls are non-rigid.  
     
     
         16 . An amphibious catamaran as claimed in  claim 15  wherein the hulls are at least partly inflatable.  
     
     
         17 . An amphibious catamaran as claimed in  claim 16  wherein each hull includes one or more inflatable tubes circumferentially sheathed in closed-call flexible foam which in turn is enveloped in a protective fabric substantially or wholly providing the outer surface of the hull.  
     
     
         18 . An amphibious catamaran as claimed in  claim 17  wherein an external surface of fabric, which is at a lowermost portion of each hull, is reinforced externally with a semi-rigid boot.  
     
     
         19 . An amphibious catamaran as claimed in  claim 18  wherein the boot Is provided with a keel.  
     
     
         20 . An amphibious catamaran as claimed in  claim 18  or  claim 19  wherein the boot overlies an internal semi-rigid strong-back embedded in said flexible foam.  
     
     
         21 . An amphibious catamaran as claimed in any one of  claims 17  to  20  wherein the bow or nose of each hull includes a tapered closed-cell solid foam core, overlaid by said sheath of closed-cell flexible foam, which in turn is overlaid by said fabric.  
     
     
         22 . An amphibious catamaran as claimed in  claim 21  wherein said nose is able to be tilted up to a beaching position via a double-acting ram.  
     
     
         23 . An amphibious catamaran as claimed in any one of  claims 15  to  22  wherein the stern or tail of each hull is able to be pushed down or pulled up, or both, with respect to the remainder of the hull by tail adjustment means.  
     
     
         24 . An amphibious catamaran as claimed in  claim 23  wherein the hulls are at least partly inflatable and wherein the tail is able to be selectively deflated to facilitate the tail being pulled up to facilitate raising or lowering of a land wheel past the tail.  
     
     
         25 . An amphibious catamaran as claimed in any one of the preceding claims wherein the hulls are removably attached to the framework by bolt-rope tracks.  
     
     
         26 . An amphibious catamaran as claimed in  claim 2  or any one of the preceding claims when dependent on  claim 2  wherein there are two spaced apart rear land wheels supported on the rear sub-frame and the track of the rear land wheels substantially equals the maximum width of the craft across the hulls.  
     
     
         27 . An amphibious catamaran as claimed in  claim 26  wherein there are two spaced apart front land wheels supported on the front sub-frame and the track of the front land wheels is less than the minimum spacing between the hulls.  
     
     
         28 . An amphibious catamaran as claimed in  claim 27  wherein the front land wheels are attached to a centrally pivoted beam axle so that the craft has 3-point suspension.  
     
     
         29 . An amphibious catamaran as claimed in any one of the preceding claims wherein all drivable land wheels are drivable in a forward or backward direction.  
     
     
         30 . An amphibious catamaran as claimed in any one of the preceding claims wherein all land wheels are steerable.  
     
     
         31 . An amphibious catamaran as claimed in  claim 30  wherein pairs of land wheels are steerable in opposite directions.  
     
     
         32 . An amphibious catamaran as claimed in any one of the preceding claims wherein the hulls are at least partly inflatable and the motor is a turbo-diesel and the construction is arranged so that the turbo is useable to inflate the hulls.  
     
     
         33 . An amphibious catamaran as claimed in  claim 32  wherein the construction is arranged so that the turbo is useable to deflate the hulls.