Replacing keelbolts on 32 ft boat - how big a job is it?

Modulation

Modulation

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My insurance survey is recommending that the keel bolts be removed for checking within the next 2 years. To be frank I was going to raise it with him as the bolt heads in the bilges looked to me to be pretty corroded - and also the steel bearing plates on which they bear. I had one removed a 4 years ago - it was about 200mm long and the whole length was corrosion-free then.
With the boards up and the bilges exposed they're reasonably accessible, but I was wondering how big a job this is? Most of the bolts still have nice hexagonal heads and will be removable with suitable sockets but 2 of them don't and will need a different approach- not too sure what!
Anyone else been through this and how did you get those bolts out??
Thanks
 
You will almost certainly find the bolts in pristine condition if there are no signs of leakage of the keel hull joint - despite the rusty heads. However if mild steel plates have been used under the heads chances are they are also rusted. Difficult to ignore the surveyor but I would ask him why they need removing, and whether just cleaning the heads up, rust proofing and painting would suffice.

As to how difficult they are to remove, that depends on access, in particular how much space you have to get a good lever on your socket extension. Usually they should come out easily, but if the heads are corroded, you may need to be inventive at getting a socket to bite firmly. Lots of penetrating oil and clean up the heads and surrounding area will help.
 
First you need to establish what kind of keelbolts you have.
For example some keelbolts cannot be withdrawn from the top and some can.
Some have hidden bolts inside the keel that without a drawing will be hard to locate.
So boat type, builder, age will help.
The builder/designer should be able to nail down the keel maker and specific manufacturing design.
 
The boat is a Beneteau 32s5 25 years old and the keel is iron. The keel is fixed with bolts (not studs) with hexagonal heads. I'm reasonably confident of all bar 2 responding to lots of leverage with an appropriate socket and plenty of penetrating fluid but it's the corroded heads I'm mainly concerned about as I don't think there is enough sound metal for the socket set to grip. Is there some other tool one can use , I wonder?
 
Six-point sockets which grip the flats can sometimes work better than normal 12 point ones. Then there are bolt-grip sockets, never tried them:
http://www.toolstation.com/shop/Aut...sd2938/Irwin+Bolt+Grip+Nut+Remover+Set/p63045
Otherwise sounds like it might be a case for hammering on a too-small socket. When that fails, cut two flat sides on the hex head and use a big spanner, which I guess you won't be able to swing in the bilge. Then get a man to weld a stout bar on the bolt head.
 
fisherman said:
Six-point sockets which grip the flats can sometimes work better than normal 12 point ones. Then there are bolt-grip sockets, never tried them:
http://www.toolstation.com/shop/Aut...sd2938/Irwin+Bolt+Grip+Nut+Remover+Set/p63045
Otherwise sounds like it might be a case for hammering on a too-small socket. When that fails, cut two flat sides on the hex head and use a big spanner, which I guess you won't be able to swing in the bilge. Then get a man to weld a stout bar on the bolt head.
Click to expand...

Or you may get away with carefully grinding the flats of the bolts to fit the socket next size down.
 
There is a long thread in the middle of p9 (sorry no good at posting links!) on Beneteau keelbolts which you may find useful.

Really would try and avoid taking the bolts out, particularly as you have already done one and it was fine. If there is no sign that the joint has been disturbed than highly unlikely any water will have got to the bolts. The ones with the corroded heads are no more likely to be damaged than the others, so would have though just pulling two others, one near the problem ones would be sufficient to show they are sound.
 
I feel that once you've interfered significantly with the bolts, it's time to drop the keel and re-seal.
I would have gone for pulling the worst one.
If it's so corroded you don't trust it to undo, I'd want it changed.

If you have a good cradle you can jack the boat on, it is not that big a job to take off the keel. but you want to be in a serious yard, on concrete with proper gear to keep the keel in place and re-align it.
Otherwise one bolt at a time and trust the sealant stays intact.
I've seen keels changed on slightly smaller boats with nothing more than a cradle, jacks, scaffolding and careful planning. And some lasers to check the alignment but that was optional!

The bottom line is I wouldn't buy or (in the long term) insure your boat with 2 keelbolts in the state you describe.
 
lw395 said:
Can't agree with that, sorry.
Quite possibly rusty under the head.
Click to expand...

See the first exchange about the state of the washers underneath which may need attention.

However, the principle stands. Corroded heads is not necessarily an indicator of corrosion of the bolt. It arises from water in the bilge, whereas the bolt will only corrode if the keel/hull joint fails.

Read the other thread I referred to. Many people have gone to the trouble (usually because of a survey report) of removing rusty headed bolts in boats such as Beneteaus and Moodys that use mild steel only to find the bolts in perfect condition. Would only attempt the corroded head ones if the washer was gone or taking the next one out and finding it unserviceable.
 
Tranona said:
See the first exchange about the state of the washers underneath which may need attention.

However, the principle stands. Corroded heads is not necessarily an indicator of corrosion of the bolt. It arises from water in the bilge, whereas the bolt will only corrode if the keel/hull joint fails.

Read the other thread I referred to. Many people have gone to the trouble (usually because of a survey report) of removing rusty headed bolts in boats such as Beneteaus and Moodys that use mild steel only to find the bolts in perfect condition. Would only attempt the corroded head ones if the washer was gone or taking the next one out and finding it unserviceable.
Click to expand...
Would you buy the boat with rusty keelbolt heads though?
If you believe the bolt is as sound as the next one, you can undo it just as easily as the next one.
If you don't beleive that, it needs changing.

Of course most keelbolts which are checked turn out to be fine. That's why very few keels fall off.
If those heads are so corroded you can't use a spanner on them, chances are there could be all sorts going on between the washer and the head and inside the washer.
 
lw395 said:
Would you buy the boat with rusty keelbolt heads though?
If you believe the bolt is as sound as the next one, you can undo it just as easily as the next one.
If you don't beleive that, it needs changing.

Of course most keelbolts which are checked turn out to be fine. That's why very few keels fall off.
If those heads are so corroded you can't use a spanner on them, chances are there could be all sorts going on between the washer and the head and inside the washer.
Click to expand...
So, how does the bolt get corroded when the water that is corroding the heads is in the bilge and the bolts are encased in the GRP and then the keel?

If you have ever seen corroded keel bolts you will know that the corrosion occurs where the bolt enters the keel where water has come from a failed joint, not from under the head downwards. Corroded heads are common in boats with mild steel bolts or nuts and leaky so water rests in the bilge. It is not a good indicator of bolt failure.

Lots of boats change heads with rusty keel bolt heads - goes with the territory on boats of this type. Clean it up, rust prevention and paint and try to keep dry so it does not get any worse.
 
Tranona said:
So, how does the bolt get corroded when the water that is corroding the heads is in the bilge and the bolts are encased in the GRP and then the keel?

If you have ever seen corroded keel bolts you will know that the corrosion occurs where the bolt enters the keel where water has come from a failed joint, not from under the head downwards. Corroded heads are common in boats with mild steel bolts or nuts and leaky so water rests in the bilge. It is not a good indicator of bolt failure.

Lots of boats change heads with rusty keel bolt heads - goes with the territory on boats of this type. Clean it up, rust prevention and paint and try to keep dry so it does not get any worse.
Click to expand...

The OP said:
Most of the bolts still have nice hexagonal heads and will be removable with suitable sockets but 2 of them don't

That to me sounds like the level of rust where water wil be penetrating between bolt head and washer.
Not a little superficial rust.
Very possibly crevice corrosion under the head.
Very possibly the washer flaking and no longer loading those bolts correctly.

It could be the OP has a different idea of how rusty is serious, I've not seen the bolts in question.
Quite probably the keel would be fine with two less bolts anyway.
Maybe that is too little margin for errors such as groundings.

But if we believe the bolts are fine, there's no reason to believe they won't undo.
And if they're too far gone to undo, they are too far gone to trust as bolts.
 
lw395 said:
The OP said:

That to me sounds like the level of rust where water wil be penetrating between bolt head and washer.
Not a little superficial rust.
Very possibly crevice corrosion under the head.
Very possibly the washer flaking and no longer loading those bolts correctly.

It could be the OP has a different idea of how rusty is serious, I've not seen the bolts in question.
Click to expand...

Lots Of "possiblies" there - hence the earlier advice to ask the surveyor why he thinks they should be withdrawn when an earlier sample proved OK. What has changed in 4 years? There won't be any crevice corrosion as they are mild steel.

They will probably be M20 bolts - takes an awful lot of corrosion to have any impact on strength of such a bolt - even if the head is corroded. The washers (or more likely plates) will be substantial and bet that even if the exposed parts are corroded, the bit under the bolt head will be fine.
 
I'd use a compressed air nut runner
will get the bolts out in seconds if the heads are sound enough
Worth hiring a compressor & nut runner for a day.
Actually shakes the rust off the threads so that the bolts come out clean
 
If they are done up as tight as usual then you are going to need a 3/4 drive and a fair amount of space for leverage which can be difficult so we sometimes opt for air tools and rattle them off.

For tricky ones with dodgy heads we have a quick grind and weld a nice big square on top.

For what its worth if I found one bad bolt I would strongly recommend that they all need checking if only for piece of mind.
If you can undo any with a standard 1/2" socket wrench then they were not tight enough anyway.
 
I have the same type of boat - 1989 32s5 and am in the process of removing the keel bolts in order to replace the washers which are almost rusted away.
Using a 3/4" 30 mm socket with an extension bar loosens them ok. A 1/2 drive will do nothing. The threads were all fine underneath the rusted head.
I have a saved few photos in 'photobucket' If you search for 'beneteau First 32s5' and the words 'keel' or 'keel bolts, it should turn up a few of the results.

Hope that helps
 
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