Big Boat Speedsailing

Return to Dave Culp SpeedSailing

dave@dcss.org

Slingshot at Weymouth, in 1978. She was 60' x 4'6" hull beam x 42' BOA. She weighed 1800 lbs, plus 4 crew. She's doing about 23kts here. Note spray thrown from leeward ama, tucked up against main hull. Her hull lines were flat aft, she was meant to plane at speed. She's in proa configuration, with all crew on the crossarm, near the pod. Note the extreme forward overhang. It was thought that forward drive from the rig would bring her down to her lines. She was built of cold molded wood, using the Gougeon's WEST system. Slingshot again, this time in trimaran configuration. Her amas were too small for her to expect to sail any distance as a true trimaran (note most crew on windward ama); trimaran config was considered an experiment, and was the configuration she was left on moorings with. She set 700 sq ft of sail. She was not expected to sail fast in light wind, and didn't.

This is Crossbow I, with her original short ama. It was later lengthened to 24 ft. Her dimensions were 60' overall (later shortened to 55'), 50' LWL. Main hull beam 1'10" (giving her a L/B ratio of over 25). She was 28' wide, and weighed 1500 lbs, plus crew of 4. She set 850 sq ft of sail in main and jib. Her hulls were cold molded, of 3 plies of 3mm Gaboon. The crew consisted of helmsman, jib sheet tender, and two mainsheet tenders; grinder and tailer. She was a bear to sail for many reasons, and it was not uncommon for her winch grinders to be hauling away, right through the speed course. Her best speed was 31.6 kts. In this photo, she is doing about the same 23 kts as Slingshot above. Note the absence of spray. It was virtually a signature of these big Macalpine-Downie boats that they threw hardly any spray, and never looked like they were trying very hard.

Photos and most information courtesy of David Pelly
Crossbow II. This boat shared the same hull length as CB1, but had two, identically shaped hulls. I don't have her overall beam, nor all-up weight. She set 1300 sq ft of sail, in the two mains shown. Her leeward hull "lead" the windward one by 13 ft, in order to give the leeward rig clear air. She was also cold molded, but of two 3 mm plies, to CB1's three plies. The hull shapes had a bit more forward overhang than CB1, and were a bit fuller aft. Both hulls had rudders, but the port had the only centerboard, while the starbord had the "planing shoe" visible above. All crew, and all cockpits were in the starboard hull. She had 5 crew; helmsman, 3 grinders--cross geared to a single winch, and tailer. The sprit booms were on the windward side of the sails, and were used to avoid the high weight of full wishbones. The clews were cross-connected, and the boat han only a single sheet. Sails were two-ply 12 oz Dacron, and all spars aluminum. The boat had no exotic materials at all, beyond epoxy glue in the hulls. Crossbow's best measured speed was 36.0 kts, in 1980, the last year she sailed.

Return to Dave Culp Speedsailing