Central skeg of Tom Cat hull

D

Doryman

New member
I don't know if skeg is the right term, but there is a fin-like projection in between the two Tom Cat sponsons. Someone asked me what it was for and I was unable to provide a good answer. Bob?
 
Its called a Nacelle , its also what the cowling around an airplane engine is called.
http://en.wikipedia.org/wiki/Nacelle
They talk about everything but Catamarans !
I believe on some boats its there to provide less tunnel slap and on single engine cats , when large , and at the rear of the tunnel it "cleans" the water that the prop bites into . If that water is mixed with air , the prop cavitates or slips. On the bow , I believe its an anti sneeze function .

Im sure that Bob and others will have a more detailed description which I will look forward to reading .
Marc
 
The nacelle is indeed an anti slap/slam/sneeze device, as Mark notes. Ideally the wing or bridge deck should be the inverted gull configuration, with the nacelle at the center. The lack of flat surfaces decreases slam--in the C Dory Tom Cat series, this seems to be a bit of an afterthought, since the wing deck does not have the inverted curve. I am sure it helps some, but still is not ideal as more tunnel clearance and the continous curve is as in boats designed by Malcom Tennant.
 
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