Vehicles for travelling over land and/or water

Claim 1

A VEHICLE FOR TRAVELLING OVER A SURFACE OF THE KIND WHICH IS AT LEAST PARTLY SUPPROTED ABOVE THAT SURFACE BY A CUSHION OF PRESSURIZED FLUID AT LEAST PARTLY FORMED AND CONTAINED BENEATH THE VEHICLE BY A CURTAIN OF FLUID FORMED FROM FLUID WHICH IS DISCHARGED FROM THE VEHICLE, COMPRISING AT LEAST ONE SUPPLY PORT IN THE BOTTOM OF THE VEHICLE, FROM WHICH THE CURTAIN-FORMING FLUID ISSUES, AT LEAST ONE RECOVERY PORT IN THE BOTTOM OF THE VEHICLE SPACED INBOARD OF AND SUBSTANTIALLY PARALLEL TO THE SUPPLY PORT, THE SUPPLY PORT BEING SO CONSTRUCTED AND ARRANGED THAT THE CURTAINFORMING FLUID FIRST FLOWS DOWNWARDS AND INWARDS TOWARDS THE SURFACE TO FORM A DOWN-GOING LIMB OF THE FLUID CURTAIN, AT LEAST PART OF THE CURTAIN-FORMING FLUID THEN BEING DEFLECTED ROUND AND UPWARDS BY THE CUSHION PRESSURE TO FORM AN UPWARD-GOING LIMB OF THE FLUID CURTAIN WHICH ENTERS THE RECOVERY PORT, A SPACE BEING FORMED BY THE FLOW OF THE CURTAIN-FORMING FLUID BOUNDED ON ONE SIDE BY THE DOWNWARD-GOING LIMB OF THE FLUID CURTAIN, ON ANOTHER SIDE BY THE UPWARD-GOING LIMB OF THE FLUID CURTAIN AND ON THE FLUID SIDE BY THE VEHICLE STRUCTURE, MEANS FOR SUPPLYING FLUID TO SAID SPACE, AND MEANS FOR CONTROLLING THE PRESSURE IN SAID SPACE IN DEPENDENCE UPON THE DIFFERENCE BETWEEN THE PRESSURE IN SAID SPACE AND THE PRESSURE ON ONE SIDE OF THE CURTAIN.