Heeled Hull Form I

When  the RC sailboats with chine continuously have greater success than  sailboats without chine I thought: should have more reasons than those already known as to improve the displacement of the LCB due to decrease in volume when the side  is immersed , decreasing the sinking bow.

And I began to study the heeled boats form.

After some assumptions I open a thread in the forum boatdesign.net about the possibility of obtaining anything about it.

My assumption was that the chine when immersed cut the waterlines so that the boat forms  would be better hydrodynamically , improving the lift carried by the hull and  improve the angle of attack required for the whole shell / keel develop the lateral force to counteract the lateral force produced by the sail.

Mikko Brummer  a participant in the forum said: “I also believe there is something to the chine and the hull lift, my example being the Star. It has a very pronounced chine, but a shallow and basically inefficient keel with a large skeg in front of the rudder. In the VPP, which ignores chines and is not very good at hull lift, the Star is a lousy upwind boat, with a very large leeway up to 10 degrees or more. In the real world, it’s nothing of the kind, but a wonderful upwind machine beating at 70 degrees from tack to tack, while heeling close to a comfortable 30 degrees and the keel root intermittently in the air. So I would be surprised if its chined hull had nothing to do with it.”

Mikko sent me a drawing of the Star that I went to the freeship to analyze their heeled waterlines :

Mikko drawing

What we see: the waterlines are perfect asymmetric foils that can develop a force against the wind.

Then I do a design with similar form to Star:

I do another design modifying this:



About Fred Schmidt

Engenheiro Naval interessado em projeto de veleiros radio-controlados. Naval Architect interested in RC sailboats design
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