Reading the CB diagram in Bylaws

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Reading the CB diagram in Bylaws

Postby vermontsailor » Tue Mar 30, 2021 9:48 pm

I'm getting ready to build a new centerboard for my old DS I. (See old posts from last summer elsewhere.) I've included the CB image from the bylaws. I'm planning on using these measurements to stay class legal, and for the fit and feel. But I need help determining the TOTAL length. It's 39" from bottom of boat to tip. And I'm guessing that "6 REF" means 6" from bottom of boat up to pivot hole, and another 6" from pivot hole to top. This would make for a total length of 51" (39+6+6).

Is my read there correct? And here is a quote from the CB construction directions, posted my Dave Misuna:

Take the time to make precise measurements, the trunk is tapered from top to bottom, and board head will have to be
shaped to match. Also check the length of trunk, max. length of board is 39" my trunk would only accept a 38" board.


He states that the max length is 39. How could that be? Unless he means max length from boat bottom to tip?

Again, help on reading this diagram would be much appreciated.
Attachments
DS CB image.png
How do you calculate the overall length of this centerboard?
DS CB image.png (145.46 KiB) Viewed 1981 times
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Re: Reading the CB diagram in Bylaws

Postby GreenLake » Tue Mar 30, 2021 11:57 pm

The bylaws don't control the CB shape/dimensions above the water line. (It should say that in the text somewhere).

The dimensions below the water line are maximum lenght, mainly because a shorter board isn't competitive (so the urge to win, will set a limit of how much you'd want to stay below the maximum) and the width can vary by +/- 1/2".

The CB trunk width is also different between different boats, that affects the max thickness your boat can support. I don't remember whether board thickness is regulated.

The "ref" numbers can only be "suggestive" because, for example, the pivot locations aren't the same for older DS1 and the DSII.

Why don't you make a cardboard mockup of your CB, to see what you can fit (and/or whether you need to round one of the top corners a bit). Thin plywood also works.
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