Originally Posted by partingclouds
The boat is a Catalina 22, without the smile... yet. The existing bolts are pure rust and should be easy to drill out to a larger size and tap. What's the most appropriate metal for new studs/bolts to mate with the cast iron of the keel?
I didn't have time earlier to go into detail. The first thing I would like to know is if you are intending to or already have removed the keel. Personally I would remove the keel before undertaking any work on the bolts. (I have had experience doing that on a few occasions.)
But I doubt that is necessary!!
If you do not intend to remove the keel I would let it be. If the bolts are rusty, they are presumably mild steel and likely they are still sound under the rust. Assuming the keel is still in place, the rust you can see must be on the nuts as there won't be very much of the bolts visible. You could wire brush them using a suitable brush in an electric
drill. A battery
drill won't go as fast. Wear eye protection and use a safety
earth leak cutout or isolation transformer. You will likely make them fairly clean again. Then buy some Res-Q-Steel ( I think that's how it's spelt. I have some but not right here.) it's messy and dark red in color and will prevent more rust if you coat it all over the nuts and visible bolts.
If your boat is out of the water
check the hull
to keel join for signs of cracking. If there is cracking get a boat builders opinion as it's likely surface cracking and easily repaired. If the boat builder
says that it's terrible and he needs to fix it at great expense get another boatbuilders opinion.
I would not try removing the keel bolts
without removing the keel from the boat which is not very difficult with the boat hauled out and a travel lift
available. Basically you remove the keel nuts with the boat resting it's weight on the keel supported by the travel lift
. Then lift the boat a couple of inches and wack the keel with a sledge hammer. The keel should drop down and be supported be a cradle
for it to rest in. Then the boat is lifted away to another cradle
As you are in a yard with a travel lift the yard will probably want that work supervised by an approved person. Again I doubt that work will be necessary.
To remove the nuts in the first place use engineering grade penetrating oil
for a few days and then a 1/2" drive impact wrench with a socket and a big hammer.
I would definitely not drill out the old keel bolts
to a larger size. You may think they will be stronger but it will be weaker because bigger bolts need bigger holes.
Likewise I would not as someone suggested drill "sister holes" as your hull
would need more holes ie perforations. Also they won't be in the correct places in the keel.
I don't think it will come to that as I'm sure your old bolts will clean up fine whether or not you need to remove the keel. You would only need to remove the keel (in my opinion from thousands of miles away) if the keel / hull join looks really dodgy.
If it is a total disaster of rust, which is highly unlikely!!! I would use the cast iron keel as a pattern for casting a new keel in lead with new 3' long keel bolts cast in
to exactly the same spacing as the old bolts. That is another story again. I'm not recommending you do that but it might be what I'd do if necessary as I have the facilities with skilled help available. It would be a heavier keel. Out of my head
, cast iron is 450 lb cu' and lead is 700 lb cu' or similar ratio.
I am though fairly sure your problem is surface rust, however unsightly it may appear to be.