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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts
Initially Posted - 05/09/2007 :  13:02:48  Show Profile  Visit Frank Hopper's Homepage
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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts
Response Posted - 05/09/2007 :  13:06:07  Show Profile
A throwback to the Star. Might help pointing... (...or they're hoping so.)
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Bill Arden
1st Mate

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USA
83 Posts
Response Posted - 05/09/2007 :  21:13:18  Show Profile
Or my old West Wight Potter... It always pointed pretty well...
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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts
Response Posted - 05/09/2007 :  22:11:46  Show Profile
Actually, it sorta reminds me of this:



Porta-bote.
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Oscar
Master Marine Consultant

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USA
2030 Posts
Response Posted - 05/10/2007 :  11:16:56  Show Profile  Visit Oscar's Homepage
They sure do point well...was watching them approach each other, one on port, one on starboard tack....couldn't be more than 60 degrees between the two of them.
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Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts
Response Posted - 05/10/2007 :  12:15:43  Show Profile  Visit Arlyn Stewart's Homepage
Pointing is not the only consideration going on with these new hull forms... as big as pointing is stopping the leeward lift traditional to most sailboat hull forms and actually make it windward lift.

There are several design considerations at play... one is the side hull form (chine) and how much whetted curvature it shows. A flatter hull chine, one where the hull doesn't produce a large bulge at mid boat but rather tapers from a hard entry towards the wider stern reduces leeward lift when it is combined with increased rocker (curvature of hull bottom). Note that the hull has a hard entry to increase the rocker length.

What is desired is a heeling footprint that instead of producing a leeward water line with a large bulge and a windward with a minimum rocker having the net effect of a longer water line to leeward than windward and thereby causing leeward lift... the new designs produce a longer windward water line when heeling and thereby lift to windward rather than leeward.

Remember... most sailboats will point 45 degrees without a problem but when heeling over and driving hard in a sea way, boats like the C25 and more especially the 250 don't produce a 45 degree course to match their pointing... my 250 has in adverse conditons suffered as much as a 70 degree course while pointing 45 degrees.

These boats turn that upside down... as the windward lift the hull produces will hold or perhaps even slightly better their pointing course.

Rememeber a few years ago when Ellen MacArthur was heading back up the Atlantic to finish the Vendee Globe and ran into a submerged container and broke her leeward (submerged) dagger board off. She was forced to single handled winch the several hundred pound dagger board from the other side of the boat and reinsert it in the leeward trunk. The reason was that the dagger board was asymmetrical and was producing much needed windward lift. She couldn't just lower the windward board and make do with slightly less depth because it would produce leeward lift. The dagger boards were built identical and reversible for just such a contingency.

Killing leeward lift and turning it to windward lift is a very important design consideration on a racing boat.
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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.