Keel Design

[Lyle Creffield]

Hi

My question relates to reducing a 1.8 m draft, 3m toe, 3.3 mean keel length, cord of 300mm attached to a 14.2m LWL crusing sloop

By reducing the draft to 1.5 yet maintaining the ballast C of G the same

Wings - not new

simply a wing of 900mm total width, same cord, same length, same ballast C of G

Provided the vertical keel area and sufficient for direction stability

why not?

[MikeJohns]

Lyle,

Reduced performance to windward with more leeway. Problems getting hooked under coral at times and makes brute force towing off much harder.

The wings will add an end plate which can compensate to some extent for the loss of keel depth (but not that much). Usually when retrofitted they often add a lot of turbulance (drag) unless very carefully designed and that means tank testing.

I'd stick with the 6 foot draft on a 45 footer if you are planning for blue water .

[Tim B]

Except that you can't see the Reynolds number effects in a tank-test, and therefore you're getting bogus data. Wind-tunnel tests or CFD are your best options for optimisation. Niether are cheap.

There is a lot of information about reducing the draught of a yacht on this forum, I suggest you have a search around. I have expressed my opinions on the matter several times. In short, "It will cause a lot of problems. Do you really need to do it?"

Tim B.