The Rot Doctor


Subject: Nail Sickness
Date: Tue, 30 Jul 2002

Dear Doc ...

We have a wooden boat that is 52 years old and iron fastened. We have some nail sickness that I would like to address with something other than total plank replacement. This boat has 2 1/2" larch planks on 5X7 sawed white oak frames spaced every ~13".

Would CPES be effective in the treatment of nail sickness? I plan on attempting to remove the wasting boat nails; or at least stop the rusting and seal them from moisture, and would like to treat the plank area that is soft ... I will have room to add a fastener near the original. I would assume I would need to use an injection process since the boat is a little too large to lay on it's side (60' and 80 tons)

Please advise ...

Niles C.


Is this the M/V Nathaniel Bowditch that used to charter out of Maine?

Yes, CPES would be your best hope for sealing the nails. I once had a 42' cutter that was iron fastened and I fought nail bleeding all the time I owner her. There wasn't any such thing as CPES back then, so my efforts were only partially successful. It worked pretty well as long as I sailed locally, but one 55 day trip across the Pacific brought all the old bleeding back. I did learn, though, that those nails could produce a lot of rust and still remain amazingly intact.

Your best bet would be to clear the head of the bleeder, use something like a Dremel tool (I used a bunch of fine nails gripped in a drill head) with a coarse grinding bit to clean down to bright metal, and then saturate the whole area with CPES. I don't think I would bother with drilling access holes around the nails, as the CPES will penetrate deeply even with just surface application. If you have the time, wait for a few days after the first CPES application and then go back and do it again.

The most permanent and watertight closure would be an epoxy filler, such as our Fill-It, which is a bit softer than Marine Tex and other marine grade fillers. It will bond with the CPES-treated area. The downside to this approach, of course, is that the filler is almost impossible to remove at a later date, should that be necessary. That wasn't an issue with me, and probably wouldn't be with you either.

And then good primer and paint, of course.

Hope this is some help, and feel free to come back if you have comments or other questions.