Centerboard Trunk Build Up

[jdubes]

Has anyone considered doing this to their trunk? I just picked up a very early prestine DSI that i plan on racing. And I was thinking about taking the time to do this. Any thoughts? Any photos? Any past experience? Below is a rule that governs what you can do to your centerboard trunk.

5.11 The centerboard trunk may be built up inside, providing that the width of the resulting trunk opening in the bottom of the boat is not less than 1 3/8 inches wide and the internal length is not less than 52 inches. The build-up may be accomplished by filling up to a height of no more than 4 inches above the bottom edge of the trunk opening. The centerboard trunk shall not be filled above 4 inches from the bottom of the trunk opening. The centerboard trunk opening shall be rectangular in shape.

Thanks Jason

[MrPlywood]

I'm not sure what that means...

[ctenidae]

What's the supposed benefit? does closing that cavity up a bit make that much of a drag difference?

[jdubes]

That's the main benefit. Whether it's recoginizable i'm not sure. I know water it's always sloshing around in that space, resulting in drag. I ask because i'm going to fair and paint the hull next week and i was thinking doing this at the same time.

[Baysailer]

Bob Hunkins keeps a collection of some key articles fropm the DS Quarterly, I've read them all, one covers exactly what you're planning to do. Here's the link to his aqrticle library:

http://www.bobhunkins.com/mt-archives/c ... icles.html

Baysailer

[Phill]

The meaning and intent of the rule is if you have a trunk opening in the bottom of the boat that is wider than 1 3/8", you may build up the sides of the opening to that width, but no narrower. Gluing battens to the sides is often seen. This build up can not exceed 4" up into the trunk. Above 4" the trunk must be as recieved from the builder. Also, this rule is intrepreted that the ends of the trunk opening may not be modified to streamline them, original shape is to be maintained

The above applies to class racing legality. If you are not going to race, it would not apply.

History...... some DS's were built with trunks 2" wide This rule allows them to use a Centerboard (CB) that is narrower than 2" and still get a solid fit between the board and the slot where it opens. The 4" rule is to keep the drag created by the water in the trunk to be equal for everyone.