Stuck swing keel

[qbot2]

Hi All, This question is regarding removing rust and freeing rusted components, so I am unsure if this is a topic that you cover. I have looked in the FAQs and not found any clues. As background, I have a sailing boat (Hunter Sonata if that helps) with a swing keel mechanism. Basically, the swing keel is a large block of cast iron (1200mm horizontal/front to back x 400mm horizontal/side to side x 250mm vertical), with a slot (900mm x 300mm x 40mm). Imagine this (pictures are much easier!) being bolted to the underside of the boat, with the long (900mm) slot on the bottom, and open (300mm vertical x 40mm horizontal) to the rear. A 1200mm x 300mm x 38mm cast iron blade pivots on a 25mm dia bolt (at the closed end or front of the keel), and swings from horizontal (up or housed) to vertical (down or vertical) under its' own weight for sailing. The chap I have just bought the boat from said that the keel has been in it's UP position for about 3 years, afloat in a marina.
I now have the challenge of freeing off and removing the blade. So far I have cleared loose flakes of rust and debris from the slot with a pressure washer, removed the pivot bolt, attatched a winch to the rear of the blade to give a constant tension, used various hacksaw blades, improvised chisels and thin strips of steel to chip away at the rust build up between the blade and the slot. The blade has moved about 40mm with approx 9 hours work so far. I am just wondering if there are any tips or techniques you have, for ways to dissolve or remove the rust? I know that a number of products are available as 'Rust Remover', but I am not sure if they would penetrate the depth of rust in the slot or if the 'coating' some of them form on top of rust would jam the blade in further? Any Ideas? With the size of the keel block and the fact that the boat is fibreglass, I have not tried using heat...
Thankyou for taking the time to read this, if you got this far!, and I apologise for my long winded description, but I do not know what info you may need, to help me.
Cheers,
Austin Holden

 

[Peterduck]

I would try to remove the whole rusted assembly from the boat if possible. If this can be done, then a fire built under the whole thing to heat it up would be a very good thing to do. The fire should remove the water of crystallisation from the rust and reduce it to a powder. Failing that, while it is still hot, toss water on to it. This will, of course be instantly converted to steam, so stand well back! During the conversion to steam, the steam explodes the rust very effectively. This should free up the pivot and the plate in the pivot block. Any remaining rust can be effectively removed by brushing molasses on to the steel and letting it steep in this for a week or so. I know it sounds unlikely, but it does work, and it works well. I hope that this will help.
Peter.

 

[qbot2]

Hi, thanks for your advice, I am using a penetrating oil and time, combined with the winch, a 5' bar and a hammer. This just seems to be one of those jobs that will take as long as it takes...
Cheers,
Austin Holden