keel nuts- rusty can you replace just the nuts

[nikksandy]

Hi, I have a moody s31 bilge keel about 15 yrs old and discovered one badly rusted nut. The bolt thread looks reasonable. No leaks etc nut is under galley area and has been dripped on. I believe moody use mild steel. How feasible is it to replace this nut without removing the keel. Has anyone done a similar job. Any advice greatfully received.
A

[brianontheroad]

you can replace just the nuts -- you can remove the nuts and inspect it if you can get it to turn....your keel should have several bolts holding it on, each one rated to hold thousands of pounds of weight so replacing that one in the water isn't going to stress them too much. you can also remove the nut, clean it and replace it or just treat it with some Ospho ..... mild steel makes for a pretty good keel bolt, it seems counterintuitive but it holds a lot of keels on!

[sailingdog]

How old is the boat? If the keel bolts haven't been inspected recently, then it would probably be wise to drop the keel and inspect the keel bolts. This is especially true of stainless steel keelbolts, as they could be suffering from crevice corrosion and could fail with little warning.

[nikksandy]

Thanks for replying to my post.
I think on further inspection I need to replace the studs and the nuts, indeed it seems likely from what I've been told that the stud will unscrew when trying to turn the nut. Is it feasible to do this one at a time afloat?

[mitiempo]

I don't think the studs are likely to come out when removing the nuts. The studs are probably buried several inches into the keel and will have quite a grip. I'd do this out of the water and it makes sense to drop the keel and rebed at the same time I think. If the studs are suspect the bedding between the keel and hull likely are as well.

[AdamLein]

Some keel bolts are threaded into a hole tapped in an iron keel. Others are bent into a J-shape and molten lead is poured into a keel mold; I don't see these coming unscrewed when you turn the nut. What's the composition of your keel?

[nikksandy]

Thanks again, Its the studs I'm told that are likely to come out with the note and I'm pretty satisfied that the condition of the studs are good. Therefore it seems to me I should have a good seal between hull and keel, Its just the nuts that are corroded. What I'd be interested is to if anyone else has carried out this job afloat. I'd rather do it out of the water but circustances are against me!

[mitiempo]

I would not suggest getting into this on the water. I don't think the keel bolts will come off with the nuts. But if they do you may have a problem. The exposed nut and thread that is slightly rusted has been exposed to air and has a limited amount of corrosion. The buried part could well corrode more.

[sailingdog]

Have you actually inspected the studs. If not, you may be in for a rude awakening... Here are some keelbolt photos by Maine Sail that show what looks like a perfectly good stud or bolt and what the reality of the section that is hidden from view is like:







If the keelbolts haven't been checked recently, it is probably well worth doing. Dropping the keel and inspecting all the bolts and re-bedding the keel is probably not a bad idea.

Originally Posted by nikksandy

Thanks again, Its the studs I'm told that are likely to come out with the note and I'm pretty satisfied that the condition of the studs are good. Therefore it seems to me I should have a good seal between hull and keel, Its just the nuts that are corroded. What I'd be interested is to if anyone else has carried out this job afloat. I'd rather do it out of the water but circustances are against me!

[rperret]

ditto - all of the above. as the old saying goes its not what you see but what you don't that will hurt you...

Question - some people have talked about "tapping" keel bolts to listen for different sounds that might indicate a bolt problem - personally I would find that hard to test - but wondered if anyone has ever heard of this.