BuiltWithNOF
Centre Board

When i bought the boat in 2002, she had a rotten cntreboard, which i removed.

I got technical drawings from the snapdragon association, and using both the old remains and the plans, commissioned engineers to laser cut a new steel board, then weld strengthening plates onto pin hole, weld a chain attatchemnt, and radius off the active edges. Then i had it shipped to industrial galvanising firm to be heated and hot-dip galvanised. finally i painted it in white hammerite, and found a new pin. I also overhauled the mechanism, which i could see only had 6 inches freeboard, thus speeding up any partial sinking, by semi-waterproofing the chain from inside the cabin for peace of mind.

On instalation, i found my strength plates near the pin were too wide, and so i used angle grinder to remove a few of the extr mm, and that is why those square patches are rusty now, i.e. the galvanising was also ground off there, but because of the quality of steel i used, you can still after 8 years use, see the grinding marks, not deep rust.

The whole plate is like new, except the grounding area which is understandably ground off its zinc.

To make it, i spent best part of a week work, and £400, and it is tested and better than the original when new, because I had the steel thickness and quality better than the builders.
this is it before cleaning up, after 8 years submerged, good as new
detail of the clever chain attatchment, so that the shackle cannot rub away
3/4
indicator system worked well visible from cockpit(hoist removed for clarity)
top of casing was sealed up to prevent fast sinking
i detroyed case to get board out, but its easily installed from under with boat lifted, i lso have the steel roller and strut that was glassed into fore end of caing and mechanisms

As far as i know, the early SD23 centre board was impossible to remove inside without slitting either the centreboard casing as i did, or the coach roof, BUT if the boat is floating or in a high cradle, its easy to slot in from below, then the single pivot bolt is put in and tightened/siliconed, and just the raising chain to connect.

What is easy is replacing it, what is not is getting one as new like this. As far as i know, its custom and originals that are still in older boats have either rotted out or been replaced with cheap steel ones that are on their way.

 

Any SD23 with a lift keel like this gets an extra knot over a bilge or tri-keeler. With this board fitted in 1963, the SD23 won some round britain race in its class, it was so fast and shallow draught. If you have a lift keel model, then the board ought to be really good or you will not be seeing reliable lifting, since rough steel catches pebbles/mud far more than a smooth A1 one.

 

It would be possible, i figured out, to use a 12V battery reversible drill with a variable clutch (cost about £40) as a motor to raise/ lower the plate electrically. ideally this would require just fitting a 3/4” adaptor, or if you like, an invisible chain drive system hidden under/within the cabin table.

I also have the cabin table, and base

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