International One Metre The K1 was designed quite a while ago now, GBR2031 was built in 2001 when I was a student. Although it's now more than ten years old, it's still a good boat and a good starting point for a development "mark 2" design featuring some modern advances. A few existing designs were looked at to gauge where the class had been and which way it appeared to be heading with respect to hull form, the only really free component of the IOM rule. The design brief was for a powerful hull form but not so much so that it would be too sticky in lighter conditions. With this in mind, I added a little more beam & moved this beam further aft to increase power but without adding too much drag, the lines were still kept quite straight. Rocker was reduced a little to maintain a reasonable buttock ramp angle. The mast and keel were moved back in the boat to balance with the new volume position but also to allow the finer bow and still have enough buoyancy when hard pressed down wind. Waterline length was maximised by having an immersed forefoot and very little stern overhang. The bow sections are relatively fine which helps to keep the bow on the surface and so make best use of the sailing length available upwind. On deck, there is a convex foredeck to shed water and also improve aerodynamics by being at a similar height aft to the goosneck. Further aft, the concave cockpit has the advantage of allowing the gooseneck to be lowered (to foredeck level), and so also lower the centre of effort of the mainsail, and still leave clearance for the kicking strap. A lower mainsail has less heeling moment and also less tendency to induce weather helm. Both of these features work to reduce global drag. The radio receiver container is thus also lowered for efficient centre of gravity. Below decks, the two servos are positioned low in the hull and one each side of the keel trunking, again this gives a good centre of gravity and minimises pitching moment. The rudder has not been placed at the aft extremity of the hull but rather moved forward a little to reduce ventilation induced by a relatively wide stern. There is still more than adequate steerage despite the keel & rudder being moved towards each other and so reducing turning moment. Stock foils and ballast from a leading British manufacturer were used in the K1. International One Metre Class Association.
|