[MHml] Bi plane rigs.

[Roy Mills]

John Scott suggested that I read page 69 on Thomas Firth Jones book 
Multihull Voyaging, which I did, not just P 69 either. The 
acknowledgement lists, along with such luminaries as Lock Crowther, 
Derek Kelsall and James Wharram, Vance Buhler a founding member of 
the BCMS, and  no less a person than Tom LaMers of this list.

	Tom gets a lot of mention in the  chapter on Trailerability. Come on 
Tom give us the benefit of your ratiocinations.

	Mr Firth Jones is obviously a minimalist in the best tradition of 
Brit seamen and shares a lot of his approach with James Wharram. His 
designs concentrate on cats and tris built of plywood and in the 
approximately 25 foot length size, in which he and his wife Carol 
have crossed "the pond" several times and cruised for months on end 
in various locations, so his experience is not to be lightly regarded.

	He tried a bi plane rig on  his cat "Dandy" with a 23 foot LWL and 
discontinued it after 2 years and 2000 miles. He initially tried it 
because Lock said " the drag of the rig is not as important as the 
actual force produced. Water drag and aerodynamic drag of the vessel 
itself are of a high order and the parasitic drag of rigging wire etc 
is relatively small"  I can go along with that but his comment is 
"Lock, I wish you had been right". Lock had sent him a drawing of a 
28 by 23 foot day sailing biplane cat,( that is extremely wide- a C 
Class cat is 25 by 14) thought to be like an ice boat so it was fast 
enough to always bring the apparent wind forward of the beam. "Dandy" 
would not do that. On a reach the leeward sail flopped about. It had 
virtues he said.  It tacked faster than any other cat he ever sailed 
( which was/is one of my concerns) and he said that it pointed very 
high but was not fast to windward. It would tack through 60 degrees 
but speed was low, when bearing off to tack through 90 the VMG was 
still not good.

	 This seems not to be current experience with biplanes. Is it the 
advent of unstayed masts that has made the difference, or larger 
sails in proportion to the boat, or hull forms more suited to speed 
than cruising, or all three, or more changes that have escaped me?

	Comments please.

	Roy Mills