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 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 giving so much background, but I do not know what YOU know.
Thankyou again,
Austin Holden

 

[Guest]

Sounds a bit silly I know, but have you tries whacking the keel with a hammer? Should at least loosen the rust up a bit. Failing that Nitric acid should speed up the process as long as you remove the residue (as you mentioned)

Good luck

 

[summerwind]

Be careful about hitting cast iron with a hammer. It is very brittle and you might find your keel comes out in chunks.

A good penetrating oil will help a lot, together with movement. I know it might sound daft, but after getting as much penetrating oil in as possible and allowing capilliary action time to soak up oil, pushing the plate back in and levering it out again will cause the loose rust to flake off and fall out. The more that comes out, the easier things will get.

You have got a mongrel of a job there. Good luck.

 

[alant]

Had the opposite problem with a swing keel Sonata - string broke & keel dropped down.
If this is out of the water, as well as previous advice, best penetration gunk available is diesel - why not dribble some of that down the slot & try to move centreplate from below. Stand clear if it drops suddenly & try to protect forward part of slot with something (wooden batten) in case it over runs & splits casing.

 

[qbot2]

Hi all, 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