[alberg30] Re: Alberg Speed

[FINNUS505 at aol.com]

From: FINNUS505 at aol.com

Hi Bob,
Do you remember the 1974 Mariner campaign for the Americas Cup? The
controversy with that boat was that Britt Chance designed a second small
transom at the bustle of the stern, beneath the waterline.
Every conventional sailor who saw this proclaimed it an abomination, and
beleived that the below the waterline transom would just produce turbulence
and drag, and slow the boat down. I did too.
Chance's theory, though, came from the fastback concept of racing cars. By
having a horizontal surface at the back of the car turbulence was caused. The
slip stream from above and below the car would slide past this turbulence, and
thus effectively created a 'longer' car, arodynamicaly. The longer the
slipstreams, the faster the car, just like the longer the waterline, the
faster the boat. 
Tank tests confirmed Chances theorys, and Mariner was built. It was Ted
Turners first 12. I think either Gary Jobson, or Dennis Conner was tactition.
Unfortunately, in practice, the underwater transom just caused turbulence, and
Mariner was a dog.  They pulled her out during the trials, and made the
experimental transom smaller, but to no avail. Courageous was  selected.
But any way, maybe when our Alberg 30 transoms are pushed into the water at
just the right angle, etc, we benefit from this fastback effect. What do you
think?
I know on my Alberg22, when the wind was above 18, and she was properly
reefed, there were times when I would heel her over to the point of the lee
rail just kissing the water, and the boat would suddenly surge forward. I
attributed this surge in speed to some suction on the windward side of the
keel being broken as she heeled over, or her actualy planing to some degree on
the turn of the bilge on the leeward side, but I couldnt be sure, of course.
It was exhilirating though, for sure. Almost like being in a Thistle or
something when they break into a plane. Say Hi to Barbara for me and Rona
Lee Trachtenberg
Stargazer #255

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