Busting the hull speed myth

Every sailor is delighted when the breeze picks up and the boat really starts to get going with a bone in her teeth. The crew will want to know how fast she will go and perhaps surreptitiously race her against any similar sized boat in the vicinity. Speculation may start about what allows one boat to go faster than another – is it the hull or the sails? It is easy to spot good, well-trimmed sails but what about the hull? The important part is not visible below the water surface. However there is one key indicator that is often very apparent – the waves generated by the sailing yacht.

When a yacht picks up speed the wave pattern around it grows and the greater the speed the bigger the waves. The energy in these waves is proportional to the square of their height – double the height and the energy goes up by a factor of four. This energy comes from the wind, via the sails and rig, making the hull push water out of the way. If less of this wind energy was wasted in producing waves