Leaking Through-Bolted Skeg

[arjand]

The bolts with which the skeg is throughbolted to the hull started leaking within 5 minutes after the boat was lowered in the water. This is not a new situation, probably there for years (dont ask). Inside the skeg there is a big vertical plate which is than welded to a horizontal plate. Both plates are from mild steel (asked the builder). There are nine bolts welded to the horizontal plate which are than throughbolted to the hull. (bolts are stainless) This whole structure is than capsulated by fiberglass but the fiberglass is not structural. The front bolts (max three) leak. his means that water is inside the skeg and than leaks into the boat. From the ouside there is no sign of any issue whatsoever. I got advise to unscrew the affected bolts one by one and try to rebed them with 5200 for now and deal with it this winter. In his view it is not problem that there is water inside the structure.

My plan of attack: Dry out skeg, open the structure to take a look at the metal if possible (1981 boat), find the source of water penetration, try to seal it, fill voids, add additional fiber glass to increase overall strength and take some load of the bolts. I can not do a lot myself but want to be on top of the yard.

Does anybody have any experience with a similar situation? Any tips/tricks? How best to proceed?

I very much appreciate any input!

Regards, Arjan

[Bash]

Great boat, the Nordic 40. In my opinion, it's the best production boat ever designed by Robert Perry.

I don't like the original proposal to rebed with 5200. You'll just make the job twice as hard when you finally get around to doing it right.

I don't understand how you'll have a chance to "take a look at the metal if possible." Would hate to see you mess with the installation just to get at a pesky leak.

[arjand]

Hi Bash,
She is indeed a beauty, thanks. You seem to imply that I should not be overly worried about the fact that there is water inside the skeg. I am worried that the probable multi year exposure to salt water has impacted the structural soundness of the structure instead of just resulting in a leak.

https://lh5.googleusercontent.com/-B...%252520002.jpg

[Jim Cate]

G'Day Arjan,

I'm not sure that I understand the layout exactly, but see if this fits:

The whole skeg is glassed as part of the hull.

There are mild steel structural components in the skeg.

There are bolts welded to the mild steel bits, these bolts penetrate the hull layup and some of them are leaking seawater into the interior of the hull.

If all those are true, then it seems that there must be salt water in contact with the mild steel structure, and if this is so, I would be concerned about the integrity of that structure. Further, there must be some breach of the glass skin on the skeg, for that water must come from somewhere.

Not very easy to examine the interior of the skeg without a lot of grinding, but it could come to that. Perhaps a call to Bob Perry would reveal just how important the interior structure is to the strength of the skeg, and how important the strength of the skeg is to rudder support.

I hope that you can find a reasonable solution to the problem.

Cheers,

Jim

[arjand]

Hi Jim,
your analysis is correct. I am in touch with the builder and the metal plates make up most of the structural strength. There are no visible cracks whatsoever so I suspect a leak at the connection with the rudder. Thanks very much for your reaction!!

[Bash]

Originally Posted by arjand

I am worried that the probable multi year exposure to salt water has impacted the structural soundness of the structure instead of just resulting in a leak.

I understand. At that point, I agree with Jim that a lot of grinding could be involved. One question you may want to ask the yard before they start this job is whether it might be more cost effective just to replace the skeg.

[Jim Cate]

Originally Posted by Bash

I understand. At that point, I agree with Jim that a lot of grinding could be involved. One question you may want to ask the yard before they start this job is whether it might be more cost effective just to replace the skeg.

Seems to me that in the process of a preemptive skeg removal one would reveal the suspect parts and thus allow inspection. If ok, one then only reglasses the affected portions. If the structure is toasted, then continue the removal process.

Anyhow, I think that Arjan is likely correct in thinking the water is getting in via the gudgeon(s). That is where localized stress is applied, and where there may be through bolts that penetrate the skin of the skeg. I think my first action would be to drop the rudder and have a good look. (Sounds easy when you say it fast).

Cheers,

Jim