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post #1 of 2 Old 01-31-2002 Thread Starter
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Twin Keels

I recently bought my first real ''cruising'' boat, a 1974 32'' Westerly twin-keel ketch. She seems to be a strong, well-built boat, and was the final result of a 2 year search; the shallow draft of the twin keel being, IMO, an advantage for Caribbean cruising and the like.

Ive heard stories about the odd steering characteristics of twin keels, especially to windward, and the partial-skeg rudder seems very vulnerable.

Any comments on twin keels in general or Westerlys in specific would be appreciated (looks hopefully to Jeff_H, who seems to have an encyclopedic knowledge of old boats)

Ive often wondered why twin keels never got popular in the US... is there a reason Im not aware of?

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post #2 of 2 Old 02-01-2002
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Twin Keels

Westerly''s bilge keel boats were very popular in Europe but found a comparitively small market over here. While ''mud berths''(the boat sits in the mud at low tide) are quite popular in England, They really have not caught on over here.

There are a lot of problems with bilge keels on small boats. Although each keel is smaller than they would be as a fin keel their combined surface area and frontal areas results in enormous drag. This results in a boat that is slower and less reliable in ''stays''. I used to teach sailing at a small charter fleet down in South Florida that used a small fleet of Westerly''s. They had a mixture of both fin and bilge keel versions of the same model. It was very apparent that the bilge keel model was much slower, more tender and did not go to weather as well.

The other issue with bilge keelers is that when you run aground you are really planted. You are there until the tide rises.

Design and engineering of bilge keel boats is tricky as well. The individual fins need to be designed to provide lift when the heeled over as well as vertical, with only one keel providing primary lift and yet minimize drag produced by the other fin that is not providing lift. Additionally the two keels tend to be low aspect ratio foils and so produce less lift for their drag.

More controversial are issues related to interaction between the two foils. As a boat moves through the water there is a zone of turbulent and disturbed water that extends outward of the foils. I have seen it posed that on small boats with bilge boards there is an interference between the fins that further reduces lift and adds to drag.

All of that said, the small Westerly''s have done all kinds of voyaging and offer a lot of boat for a limited budget. Skip Beaufort''s ''Water Dog'' (might be ''Water Puppy'' but I think that is the dinghy''s name.)spent many years cruising the Bahamas and Carribean.

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