As Graham say, impressive stuff Martijn. As far as the buoyancy provided by the mast, I wouldn't count on it, with the early boats any way. Vagabond (no 10) had a solid plug in the bottom of the mast. When I managed to break it, (the mast ran away from me when de-rigging and snapped on one of the winches), a litre or so of water came out of it. Later models have a "breathable" plug in the bottom, so I assume they drain.