During the first ‘sea-trial’ the centreboard did not fully extend. Because my centreboard case is open at the top, I could quickly establish that it was not binding anywhere on the sides. You can see ‘daylight’ between the board and the case, and the inspection ports do not interfere.
My only explanation for the issue is that the geometry was not quite right. That is, either the holes for the pivot in the keel and/or the location of hole in the centreboard were not in the right position (e.g. the pivot was not in the centre of the arc of the trailing edge). That could cause the trailing edge of the board to make contact with the rear of the centreboard case. This is not something that can be easily tested earlier while the boat is upside down in the shed (or on the trailer).
Some time back when I was building the keel, I noticed that the position of the pre-drilled holes were way off. At the time, I filled and drilled a new hole to match the one that ‘made sense’.
However, it seems that this hole (or the predrilled hole in the centreboard) was also not where it needed to be.
Fortunately, I can get to these bits while the boat is on the trailer. This was the procedure to (hopefully) fix it:
- drill out the pin and drop the centreboard.
- wrap credit cards in cling film and wedge them between keel and centreboard to cover the holes on the inside of the centreboard case.
- fill all holes with thickened epoxy.
- clean up and re-drill the holes in the keel.
- position the centreboard and support it with wooden blocks. A wedge between the trailing edge of the centreboard and the back of the centreboard case kept the board as far forward as it can go.
- mark the new position for the pin on the centreboard.
- fill and drill the new hole
The centreboard has essentially shifted more than 1/2″ forward (and 1/8″ higher) inside the case. The first photo shows the bigger gap between the rear of the case and the trailing edge of the centreboard. The additional clearance will hopefully allow the board to swing freely through the case.
I installed temporarily a piece of 8mm SS threaded rod with two nuts on either side. If it all works satisfactorily on the water, I’ll cut the rod to the correct length and ‘bury’ it in epoxy. A lick of paint will finish the job. The bare patches on the keel are only missing primer and paint. The glass and epoxy are perfectly fine.