Shimming the centerboard side-to-side

[jimesh]

As noted in another thread the P35 centerboard 'klunks' side to side when it's all the way down and not side-loaded to one side of the trunk by sailing forces (i.e. when at anchor etc.). Raising it fully always stops this. The board has a lot of space for horizontal travel on it's pivot pin in other words. Maybe too much.

I'm considering adding shims between the board and trunk on either side to keep the board centered in the trunk -- basically very large washers on the pin on either side of the board. That should eliminate 'klunking' in the down position when not sailing -- it's a nuisance to always have to lift it in such cases for us. It also seems to me that that might help take some of the twisting force and wear off the pin and its mounts, and transfer it instead to the sides of the trunk directly from the board via the washers.

The one possible problem that I can see is that the usual fouling growths might squeeze into that space and make the board hard to move after a while. If the shims fill the whole space and are not over, say, 6 inches in diameter I think that might be avoided. The leverage of the board's weight and raising and lowering it from time to time should scour any nascent growth off. The shim material would have to be bronze discs or some other non-swelling material that doesn't absorb water and swell up so hard as to jam the board over time.

Has anyone tried or considered this? See any problem with doing this?

[cheeryo]

The board is designed to be "sloppy". If you take the excess space out, the board will be difficult to raise and lower. According to "Sound Rigging" they have had several customers tighten up the board resulting in the board jamming.
This is the drawback to a centerboard. I just keep it up when not sailing on the wind.
Jack

[jimesh]

Okay. Thanks again for the good advice. I guess it's just something that we'll have to live with.

[jimesh]

Just remembered why this is an issue for us. ( How quickly we forget when not sailing. Oh for a year-round sailing season.) There are two situations when it's very preferable to have the board down: (1) On the mooring when we're on board and the waves are from just the right direction with the right spacing the boat will roll excessively unless the board is down. (the 35's hull does not have much form stability) (2) Likewise when off the wind sailing in 3 - 4' seas having the board down stabilizes the boat and reduces rolling. (This is particularly common on Buzzards' Bay, our home waters.)

Checking the trunk and board fit reveals that the board tapers from head (pivot pin) to foot and that it almost fully fills the trunk at the head, at least along its leading edge visible from below. So, as Jack notes, there's not much space to be shimmed along the pivot pin and doing so seems likely to cause it to jam due to fouling (which I see a lot of on our board.)

I'm wondering now if the klunking in the above situations is more from the board twisting on the pin due to the sloopy fit than sliding sideways -- the loosness of the fit that several have noted allows this. Would making the fit of the board to the pin tight, e.g. with an epxoy-glass fill and re-drill, lessen that? Is the loosness of the fit intentional in the design to reduce twisting forces and wear on the pin, a trade-off, with the klunking consequence? How do other centerboard boats deal with this problem? Certainly not all experience it?