Abstract: The invention provides a crawler track belt assembly with flexible parallel belts interconnected by transverse grouser bars. The bars have guide portions spaced transversely apart and mutually aligned longitudinally with guide portions of other bars. A track bed of the vehicle has parallel, longitudinally extending, guide grooves which receive and guide the guide portions of the belt to maintain track alignment. To reduce belt tension, the lower track bed has a lateral profile which resembles a catenary. The vehicle body has spaced sponsons defining a hull tunnel therebetween, and in water is powered by a water jet having a primary intake adjacent the tunnel roof. If the primary intake becomes blocked, a secondary intake on the track bed is swept by the crawler track belt assembly to maintain the secondary nozzle free of obstruction. The water jet discharges through a rotatable nozzle which can be directed to assist in clearing the primary intake of blockage.