Although there are differences in the sailing aspects of the two designs, their measurements are very close, with a waterline length of 18 ft (5.49 m) and an average beam of 6 to 8 feet (1.83 to 2.44 m), not including the wings. With wings the maximum beam is 14 feet for the "International 18" and 18 feet for Open 18's sailed at Sydney Flying Squadron and Skiffs Australia. When the boat is dry it should weigh not less than 375 lb (170 kg) including wings, foils (centreboard and rudder) and the number one rig of sails, spars and ropes.