Keel Bolt inspection

[pat_detente]

We have a Moody 33 Mk1 fin keel. The survey suggested that we check the keel bolts but I am unsure how to do this. The tops of the bolts and nuts are glassed over. Can anyone tell me what I should be doing? After removing the GRP do I :
a) check the nuts are tight;
b) remove the nuts to check the threads;
c) remove the nuts and check the studs are tight;
d) remove the nuts and try to remove the studs (not all at the same time, natch!).

If I am to remove the studs, what am I looking for? Corrosion, obviously, but what about cracks, evidence of minute crevice corrosion?

Any advice will be gratefully received!!

 

[MoodySabre]

Go on the Moody Owners Association website and look there for some specific advice for your model. If you don't belong then register and look. Loads of technical stuff for members make it worth joining.

 

[tillergirl]

Having replaced keel bolts three times on two wooden boats (over quite a long period of time), my immediate action is not to do any of that yet but to do some further thinking and if you are still worried to have them x-rayed.

My reasoning for this is that the only way to really check is to remove all of the studs and inspect them. I had a bolt completely gone and the top nut looked in the best condition of all of them, the thread on the top of the bolt was fine and the head underneath (it was a bolt not a stud) also looked fine. Yet if you put a big spanner on the top nut it turned because it was not joined to the bottom! Another nut also tightened slightly but when the bolt was removed, it was clear that the nut had been tight and what we had done was twist the bolt!

Yes sure these are extremes and they had been in there ages but I think the principles apply to a GRP vessel. a and b don't really confirm anything.

But do you really want to chip away that GRP inside? What is the evidence that you can see. On the wooden boat we could see rust weepage at the keel/keelson (the wooden bit) joint. Rust expands so it needs to force its way out. Have you any signs of weeping rust at the keel/hull joint? Is there any signs of dampness/rust inside? If yes to either, its worth a full investigation I would suggest. In not, is any there any signs of movement at the keel/hull joint? If yes, that suggest looseness and its worth doing a. But that still leaves you with the issue of whether to remove the studs. I guess the surveyor hasn't found any signs of movement otherwise he would have said so. So his recommendation is one of those sensible things that professionals have to say (and genuinely mean) but do not need to instill fear and need a sensible and measured response. My view would be that if the current arrangement is sound and this is merely a sensible precaution because of the age of the vessel, I would not want to disturb what has worked well in the past and which would need reinstatement when the investigation is over. If the answers to the above are no and you still are worried, get them x-rayed.

Hope this helps

 

[steve_cronin]

\"Check the Keel Bolts\"

HA that old surveyors' chestnut.

Intended to cover his back of course. However, that isn't to say that you might not have cause for concern.

As others have already said, X-raying is the best way to have a look and to know if the studs are likely to snap off if you try to remove tight nuts. Some keel bolts narrow severely in the section which goes through the hull and therefore weaken to a fraction of their original strength (waisting) so when you put your socket wrench onto them they just snap off. From outside appearance they look perfectly OK.

This must be done out of the water of course.

Steve Cronin

 

[jwilson]

As others have said, the surveyor is covering his back....

The entire studs need removing to check - a big and sometimes difficult job.

As a general rule, if the inside glassed-over nuts look OK, and there is no weeping of rust from the keel GRP jointline externally, they are probably OK (but might not be). If you get lots of weeps of rust from the keel/hull joint you probably definitely do have a problem. Your Moody must be over 20 years old, and I have seen Moodys of this age with keelbolt problems. (Also some with no problems).

X-ray checking is good, but getting more and more difficult/expensive to get done because of elf' and safety.

 

[boatmike]

If you can get an X-Ray done it's a good idea but not always as easy as it sounds as the angle at which an X-Ray wants to be at is ideally 90 degrees to the bolt. Hopefully it's possible.
This is a fairly normal surveyors "jobsworth" comment though, and I would agree with others that if you have a sound hull to keel joint without rust weeping you are probably OK. If you can lock 2 nuts on the stud and remove it from within remove 1 at a time. Any problem will be evident fairly quickly. The chances are though that releasing the thread from the iron keel will be impossible this way (though worth a try) The only proper way to do the job is to drop the keel and have a look. Not as difficult as it sounds. You need the boat on a proper cradle with about 24" inches clearance under the keel for a couple of hydraulic car jacks. You also need to rig up some side props that are properly braced to stop the keel falling over. Drop the keel slowly until the bolts are free of the hull. If you need to replace any you may need to apply heat with a welding torch or similar to get them out but hopefully you won't need to. The advantage of the exercise is that you can apply loads of sikaflex to the joint when bolting up again for a nice new seal and you will have the confidence of knowing it's OK.

 

[chrishelen]

Why glass em over in the first place if they were not weeping,any glassed over fittings must be treated with suspicion, you need to get at the things to give them a nip every now and again, i would draw one just to be on the safe side,but not under the engine bay as these are probely preserved,xraying is very expensive. yes i would draw at least two, rgrds chris.

 

[jwilson]

I think you'll find Moody glassed them over when they built the boat. Very common to find this - doesn't necessarily mean someone's tried to cover up a problem. On a GRP boat you don't usually ever have to tighten them - unlike wood where the timber sometimes compresses over time.

 

[chrishelen]

I stand corrected,although i think you will find you would like to be able to check somthing as VITAL as as a keel bolt after a rough passage,even in a moody you might ground the boat,and keel bolts do work loose and unless the are magic bolts they stretch.rgrds chris.

 

[Piddy]

Our Moody has never had them glassed - and they make the bilge water rusty.

I wish they were but can't imagine the glass would stick to them now.

Cheers

 

[chrishelen]

Paint the blighters.

 

[Ruffles]

A number of peeps have posted on the MOA fora on having their keel studs drawn and checked. From what I remember all reported corrosion on the nuts but the studs found to be in good condition when drawn.
Of course yours may be the exception!

 

[pat_detente]

Many thanks for everyone's advice - it has been illuminating and very helpful. We will join the MOA - we had intended to and this is the spur to get on with it. We understand that surveyors often cover all eventualities but, being in the survey report, the insurance company won't cover any event that could be related to the KBs unless we follow the recommendation, so we have to go down that route. Unless something else comes up in the MOA, our current intention is to try removing the studs, and if unsuccessful on all (likely) we will have the keel dropped to inspect and so also get the benefit of resealing the joint.

thanks again to all who replied