The Grand National (GN) endurance race was once 100 miles or more. (The boats must carry 50 gallons of fuel.) Today a GN race may be 5 miles, one hour, two 10-lap heats, or a combination of the above. Grand Nationals draw crowds to the riverbanks to hear the roar of engines and feel the suspense: Who can hold out to the finish line? The class uses any V-bottom or monohull up to 25 feet long. No tunnel over 1 inch deep, hydroplane or step-type hulls are allowed. The GN race boat is propeller-driven, powered by a U.S.-made automotive or light truck Chevrolet or Chrysler engine mounted rear of amidships.