Tuesday, October 24, 2006

Planing and trapezing

The development of the sailing dinghy was helped in the early 20th century by Uffa Fox (1898-1972), an English boat designer and sailing enthusiast. He developed and contributed to many dinghy classes which are still with us nearly a century later: the Albacore, International 14, the Firefly, and the Flying Fifteen.

He also introduced the major advance of hull shapes which can plane, and which can therefore reach beyond the usual speed limits for small sailing boats. In effect, a boat which is planing is skimming along the surface, rising up on its own bow wave. This results in less friction because of reduced waterline length, reduced displacement (the amount of water needing to be pushed aside by the boat), and reduced 'wetted area'. The power given by the sails has to overcome less resistance, and therefore speed increases dramatically.

In 1928 Uffa Fox introduced planing to an astonished racing world in his International 14 boat, the Avenger. He gained 52 first places, two seconds and three third places out of 57 race starts that year.

Another advance in dinghy sailing was introduced in the 1930s, when the technique of trapezing was introduced. This involves using the crew to provide more leverage to keep the sails vertical, by hanging outside the boat on a harness and rope attached to the 'hounds' or upper mast. As a result the boat is easier to keep upright, and the sails can deliver maximum power most of the time.

Trapezing during a race first appeared in 1934, on the Thames A Class Rater Vagabond sailed by Peter Scott (son of the famous Scott of the Antarctic), and John Winter. The owner of the boat, Beecher Moore, of Thames Sailing Club had worked on developing the technique, in discussion with Uffa Fox. Vagabond was spectacularly successful in that race, winning by four minutes.

Sadly, the innovative technique was immediately banned, and received little development until it was reintroduced on the Osprey and Fiveohfive Class (505) in 1954 by John Westell and the Flying Dutchman class in the early 1960s.