Keel base plate

The keel base plate is made from a solid piece of 12mm thick steel about 6 meters long and around 40cm wide, it weighed hundreds of kilos so was moved with chain block and rollers etc.

The photos show keel base plate preparation work. Making sure the bottom of the keel is leveled off for the plate to fit on top, so the welding gap is correct all the way around.

 Moved up to large oxy-acetylene tanks for cutting steel hull plates (small ok in the frame building stage). The 12mm base plate cutting needed large cutting tips and alot of gas. It may be possible to provide a full-size template to a steel fabrication shop and they could plasma cut the keel base to shape.

This photo shows the keel profile shape. It is a NACA designed foil section. A 4" hollow pipe on a raked back angle forms a nice oval leading edge shape horrizontally. The keel has 6 compartments with 5mm plate bulkheads. These bulkheads extend to floor level inside the hull making the keel very well braced for extreme sideways forces. Moving front to rear the first 3 compartments house the ballast. The 4th and 5th are water tanks and i made the final thin compartment a sealed void (others use it as a tank, its a stove-kerosene tank in Nicks plans). The first 2 ballast bulheads have 45 degree cutouts on the corners, it should elliminate the chance of metal fatigue cracking where 2.2 tons of ballast gets thrown around by the sea. The 2 separate water tanks (25 gallons and 45 gallons) are fully sealed at the corners.

Sorry no photos of the plate making or raising. But i used a standard masonite template as the other plates were done. The keel base plate was about 10mm wider than the keel sides, sits ontop with  T joins to the keel sides. This join is probably strongest and is per design. 

(Also it allows the optional keel winglets could be attached..that a story in itself - to cut a long story short, i started building the 5" winglets, got the lower side in place on both sides but after awhile realized it was all too much time and work, and decided to "keep it simple" so oxy-cut them off and reground the ragged base plate edge smooth again. If you want to win the Ammerica's cup or something like that then build the winglets, i don't think they'll be necessary on the 4'3" draft keel version, (useful on the 3'9" draft keel version though, eg wylo35 Mahina ))

So the base plate was cut out and edges ground with the 9" grinder. (sorry cant remember peening it, if i did it would need a sledge hammer).  A strong angle steel was welded to one side of the hull and braced to take the 1/2 ton chain block, then it was raised into position and tack welded on. Shade cloths went back up. Final edge measuring, scribing and grinding followed.