ULDB, Ultra Light Displacement Boat

An ultra-light displacement boat: a long, narrow, very light offshore racer designed to plane and surf downwind instead of pushing through the water at displacement speed. The type, nicknamed sleds, grew on the US West Coast in the 1970s and 1980s, with Bill Lee’s Santa Cruz designs and the 67 ft Merlin built to win downwind races like the Transpac to Hawaii. A low displacement-length ratio is the defining metric. ULDBs trade upwind and heavy-air comfort for downwind speed in the trade winds.