Author: AYRS Webmaster

This project has been undertaken with the aim of finding a method by which the length of a surfski kayak can be optimised in terms or having least possible resistance. Surf ski kayaking is a highly competitive international discipline that takes place on open ocean, it differs from other forms of kayaking because of the lack of regulations regarding the length of the boats. An aim of this work was to determine if the boats on the market today are fully optimised in terms of having a length with least resistance. Through use of software that incorporates thin ship theory as well as skin friction data from ITTC ’57 it was possible to calculate the wave making and frictional resistances for a series of lengths of Wigley hull forms with constant displacement and beam. This allowed a total resistance to be calculated for each length which in turn leads to an apparent ‘optimum’ length. In terms of boats currently available, it appears from the results that they have indeed been optimised effectively however only for a small weight range of user. A conclusion of this work is that there may well be scope for manufacturers to produce boats better suited for other weight ranges of kayaker or paddler as they are more often known.

Multihulls can be light and fast but cruising ones must never capsize: They stay inverted.
Single hulled yachts can be self-righting and seaworthy, some large and small ones can survive storms and work to windward in gales but to be quick they need deep weighted keels and a wide hull. Built in buoyancy can avoid sinking but they are outperformed by multihulls.
Can a multihull be seaworthy? Could one work to windward in a gale or sail on when mid Atlantic breakers flatten her? What about an automatic system for capsize recovery? Could a multihull heave to in heavy weather and work slowly to windward like a Contessa? Probably not, but perhaps it could be as seaworthy as the offshore racing fleet.

Back in 2002, AYRS Member Slieve MacGalliard was looking for a way to improve the one weak point of the modern western Junk rig – the windward performance. His conclusion was that camber is needed right to the luff of the sail, a feature that is difficult to achieve with the standard rig, which is normally pulled aft. One possible idea was to build a cambered rig with a lot of sail balance forward of the mast and split the sail in way of the mast so that the camber would be the same on both tacks and not distorted by the mast.