Thing is Epiph wants a 2" deep beam that is 8" wide. The width is a valiant attempt to gain some mass, so that the unusual shallow beam will not want to bend. As I understand it, the original concept is to create a number of mini verticals inside the 2X8 to get that on edge stiffness in the width of the proposed bridge.
The problem is to create a non-flexing structure in a 2" X 8" parameter.
I'm absolutely sure that you cannot cut 2" wide vertical arcs out of ply and glue them side to side to make a 2" X 8" curved beam. You can ofcourse, but the resulting pieces are essentially 85% SHORT grain. And the finished piece no matter how much epoxy glue will not be very strong The only way to get the full benefit of ply is to glue it up in a short stack conventionally.
A solid 2" X 8" glued up mahogany plywood beam wouldn't weigh much more than the 8# of the original white oak one. The beam is less than 4' long. There isn't very much to bend here.
But it might bend.
But it WILL NOT BEND if the 2" X 8" beam is supported at the ends AND WITH
ONE OR TWO COLUMNS. A well constructed strut that has a very solid base.
You could put a compression pole right under the mast down to the keel and get away with no beam at all. Done all the time.
The original beam is 4 1/4" in the middle tapering to 2 1/2" on the ends. It is 2 3/4" wide. It is a very efficient, nice looking piece as designed. In no way could it be bent by the mast. Unless it rotted.
The only way the cabin top flattens (and it is really minimal: 1/2" maybe a bit more, limited experience here) is that the wood structures in the boat settled (and/or the balsacore in the composit cabintop rots) - with help from above. The beam remains unchanged. The bulkhead, beam and vertical struts were all carpentered DRY into place by the factory. Designed to move in time!!!
Dry means no glue was used (in 338). When anybody renovates in 2006, you want to glue in a monolithic composit solid mast support. No fooling around this time.
Can we get Epiph's 2" minimum??? No problem!
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