My boat Smokin was built by Ron Hall, the centerboard bolt does not go through the sides of the centreboard case in the normal manner, so I guess it is somewhere in the keel with filler and paint hiding the bolt head and nut. 
What would be the best way of altering this to a more conventional system? 
Would it be as easy as bonding some ply to the case above the location of the current bolt and just pushing a drill trough and fitting a bolt before removing the old one and filling and refinishing the old holes?

Hi Martin - sadly not so simple, I considered the same thing on my last boat and did some cardboard try outs and couldn't get the board to work in the same way with a different pivot point.  In the end I epoxied some seasure gudgeon bushes into the original large bolt hole and put a bush through the board as well so water didn't get into the ply of the CB case as it had done previously.  I could then put a more reasonable bolt through - it had been 1/2 inch brass.  Try the paper /cardboard pivot test and see how the position changes.

Why change it?  I have the same in Love on the Rocks (3489) and although it is a bit of a pain when you need to get the centreboard out, it does mean that you have removed one way for water to get into the boat (except over the sides!!!).

It's possible if you look at the geometry.  If you drill the new hole as far back from the old as you raise it then the leading edge will be in the same place with full board down but you will lose a bit of length.  I do remove the board from time to time to repair the finish and edges.  It's possible the pivot bolt is on a bridle down the case?  If so should be easy enough to convert.

Hello Richard I was unsure if yours was the same or not, what did you use to cover the bolt heads priror to painting. Did you photograph it when you removed it by any chance?

I would agree with Richard, don't change it. When I had Uptown Girl the 'bolt' was in the keel. But there was no bolthead or nut, just the body of the bolt, held in place with coloured plasticene smoothed off at keel level. Worked perfectly, and was a doddle to remove. Nick

The first time that it was removed, someone had covered it with filler and Dirtyhands found it a pain.  It was then covered with silkaflex, smoothed and then painted over.  Makes removal very easy.

Call me if you want to talk further.

Hi martin, as richard says when its been filled faired etc there is no trace,makes it 1 difficult to locate, 2 hard to remove without damaging the finish, hence the reason for using sikaflex,it finishes smooth ,but leaves a witness edge,it pulls out quite easily when needed and when cured ablob of paint to colour, if you need any help ring me rgds phil

Martin,

Having sailed against this boat a few times I seem to remember that the centreboard bolt is fitted in the keel and only accessable from the underside of the boat.

You are correct - the best way to locate it is to crawl under and part the slot gasket so that you can see the bolt/pin.  Use its location to identify on which side of the keel the opening has been made for the pin - look for some slight distortion in the surface.

In the cold, fairly still, days of the winter it is noticeable: and leads to very cold feet for the crew.
I am hoping that in windier (self-bailer open) weather it wont be noticeable.

But in the mean time: Any ideas for stopping a persistent leak around the centreboard bolt on a Winder?

Replace the rubber washers?

& make sure you have put it back in with the washers in the right order, nut, s/s washer, rubber washer, case, rubber washer, s/s washer, bolt head.  Try a bit of vaseline on the rubber washer if still leaks and make sure the bolt isn't over length.

Thanks Andrew.
Should I tighten the bolt up tight? or only enough to just compress the rubber washers?

I've a wooden centrecase and generally tighten it up firmly by hand then a gentle tweak up with a spanner to compress the washers but not tightened up as hard as I can go.