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How To Build A Unique No-Pin Swing Centerboard
 
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Unique centerboard rolls on a curved track trunk top

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Here is a good centerboard idea that is not too well known. This configuration originated on the International 14 class boats. It was probably an Uffa Fox idea and a darned good one at that. Sandy Douglas used it on the Thistle, the Highlander and the Flying Scott.

Because I haven't done plans on this 70-lb. Blivit 12, I thought that some sketches & photos to document the technique might be worth while.

centerboard photo

The troublesome hinge pin is not required. . . the board simply drops down in the slot and rests on rollers that run on a curved track. There are matching radii on the forward bottom of the trunk and the forward end of the board. This configuration provides an action similar to rotating on a pin.

The result of all of this is that leaks are eliminated and the board is easily removed. It still retains all of the swing board characteristics and needs to be weighted. Therefore quite a bit of force is needed to raise the board so some kind of tackle is required. The simple lift out feature makes it ideal for car-top boats, especially on my Geodesic Airolites.

centerboard in use

NOTE: If this looks too complicated it probably is - and you had best forget the whole idea.

NOTE: Seal inside trunk and top surface of roller tracks with double epoxy coat.

SUGGESTION: Make a fullsize cardboard pattern mockup of trunk side and board. Use a 2 1/2" diameter bottle/jar cap for a roller pined to the board. Now check the actual shape by rolling it against teh 2" radius of item 4.

trunk diagram

board diagram

RIGGING: The line for a four part tackle starts at an eye at the mast step. It goes back and forth from board to step with three truning blocks located ath teh step. Adjust and secure it to a cleat monted on the top ot the thwart (as seen in the first photo.)

board head diagram

material list

 

 
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Aladdin Products, Inc. d/b/a
Monfort Associates
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