Abstract: A tank including a bottom portion, sidewall portions and endwall portions forming a unitary structure with a top opening, a plurality of support sections spaced about the periphery of the structure, the support sections including buttress sections extending from the bottom portion upwardly toward and terminating adjacent the free edges of the wall portions, each of the buttress sections including a main surface that is spaced from the wall portion adjacent the bottom portion and converges toward the wall portion adjacent the free edge thereof, the support sections including base sections extending upwardly from the bottom portion a fraction of the height of the wall portion, each of the base sections including a main surface disposed substantially parallel to and spaced from the wall portion, each of the base sections including a top surface substantially parallel to the bottom portion, the base sections being disposed between the buttress sections, the base sections being disposed along one wall portion in p

Abstract: The combination of a snowmobile and a watertight hull with propeller drive shaft wherein the snowmobile has a drive shaft which includes telescopically extensible section on both ends of which universal joints are provided so that the snowmobile drive shaft can be readily disconnected from its traction tread and connected to the propeller drive shaft of said hull.