Rusted Centreboard

[audacity]

I have a galvanised mild steel centreboard that is rusted solid in the cast iron keel section. I have dropped both off of the boat and would appreciate any suggestions for freeing them without excessive hammering as I am afraid the cast section could shatter. Photos available on request.

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[LORDNELSON]

I have heard of someone using an industrial size hacksaw blade with a handle at one end to cut through the rusted areas. This was on a Southerly which has a cast iron grounding plate/keel box and, I think, a cast iron swing keel.

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[Mirelle]

Just a thought. There is usually ample clearance between plate and ballast keel. What often happens, though, is that small stones get jammed between the two - the effect is much the same, of course! If the plate is over to one side that may well be the cause. If you can poke a bit of flat bar down between the two, from above, and tap that a bit, you may manage to knock the stones out.

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[William_H]

The listed solutions are worth considering however if it really is rust you may be able to apply heat to the centreboard or better still tot the casing. The expansion tends to break the corrosion bonds from internal stress. Clearly however this is a last resort and it may still require serious bashing with a hammer. The heat should be approaching that of a red glow if necessary and if you can get it that hot but be carefull not to heat anything but steel . I am guessing you are resigned to the fact that you may have to throw away the centreboard and casing so go to it with the heat and hammer.

While I am on crazy schemes if you do throw away the centreboard casing and external keel consider a redesign with flat bottom vertically dropping balasted centreboard of fibreglass with lead inside and additional balast internal under the floor. My 21 footer has aerofoil shapel cb with 100 kg lead and another 200 kg under the floor. The keel when retracted comes up to the cabin top and is just clear of the hull bottom so that it will settle very flat float in inches of water and rolls onto a trailer easily. The best part is that the performace of the boat because of this keel is vastly better than anything else around. Forgive my wild suggestions its just that you would be amazed what a good keel can do to your boats performance. especially to windward

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[qbot2]

Hi, had this problem on a Hunter Sonata Lift keel. The previously suggested ideas did not work totally, but each one removed some small amounts of rust ( i got rust flakes 1/4 inch thick by 2inch dia coming out !). you could try using a 3/16th flat bar, chamfoured at one end (like a long chisel) and harden the point. I had to drill up the side of the plate and keel housing in the end. it took about 20 vertical drill holes each side to free off enough to move. good luck. let me know if you still have difficulty. i was contemplating using a chemical bath to eat the ferrous oxide (rust) at one stage!
Cheers,
Oz

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