From the DSA Bi-Laws:
6.1. The thickness of blades is not controlled. Tolerances of blade profiles are plus and minus
1/4 inch unless otherwise specified. Leading and trailing edges shall be parallel plus or
minus 1/4 inch.
6.2. CENTERBOARD: The centerboard shall be of built-up or molded fiber-glass and resin
material or of wood covered with fiber-glass and resin. The profile of the centerboard
shall conform to Drawing 6.1 and Drawing 6.2. The centerboard profile shall be a fair
curve between reference points A and B.
6.3. The weight of the centerboard, including any fittings permanently attached, shall not
exceed 25 pounds.
Now my story:
About 15 years ago, a previous owner replaced the stock centerboard on #568 with a custom foil. The owner had wanted as thick a board as possible to maximize lift potential. The new board core is “aircraft grade” spruce. Although fashioned to dimensions within the legal specs, it was glassed up to allow only about 1/32” of space between the trunk wall and the board (1-9/16” at it’s thickest point).
When I bought the boat in 2001, the board was snug but came down with a little effort. As the years passed, it became increasingly difficult to lower, eventually resulting in a broken handle (which had already been damaged/repaired) and several attempts at fairing the board down to bare glass. Now, I have another bent handle, and the board is next to impossible to lower, even with added leverage.
Having read the many comments in this forum on “water in the board”, I think I can say this board is not so affected. There is no “dripping” from cracks, etc., and I can’t believe it’s retaining water, as it has consistently weighed in at 22 pounds. Even now, with the board out of water for almost five months, it’s the same weight and dry as a bone. It's occurred to me that the CB trunk has changed shape somehow, causing the CB to jam; but I don’t see any evidence of this, inside or out. Could the board have swollen due to the elevated level of moisture in Portland, OR relative to where the board was made and custom fit in Fresno, CA? 'tis a mystery.
I took the board out for about the eighth time a couple of days ago (it comes out from below with a certain ratio of leverage and verbage) swearing to rectify this situation once and for all. My plan is to shave a ¼” off the thickest part of the board, about 4” aft of the leading edge, down to where the taper starts. I’ll do this by cutting three to five ¼” deep grooves lengthwise along both sides of the board with a circular saw. This should cut through the fiberglass and into the core about 1/8”. I’ll then chisel out the excess and belt-sand to profile. With a little luck (maybe a lot) I won’t simply replace the thickness as I re-glass/gelcoat the faired section of board.
Before I perform this fat reduction surgery, I thought I’d toss some questions to the crowd:
1. Given the observations above, why would this board be getting too thick for the slot?
2. What is the desired thickness of fiberglass for foil strength (how many layers of matting achieves 1/8” of thickness)?
3. Can you think of anything that might suggest what I’m about to do is sheer folly and will end in wailing and gnashing of teeth?
Process pictures to follow.