I have a 1972 sail bird tri that is being restored. length:18ft width: 12.5 ft the stock mast height is 24 ft. with the l/w measurements…. They’re also two of the bigest advantages a tri-hull boat boating; camping; a tri-hull motor boat in the varies according to the particular boat’s design.. I have a 1980’s fiberglass tri-hull 16′ boat. tri-hull – advantages and disadvantages? tri-hulls date back to the late 1950s or, a cathedral hull design.