Hull Deck joint caulking

RossC32 · #1 09-09-2011

Hello,
I have a Wauquiez Centurion 32. There are a few leaks at the hull to deck joint. The joint itself is capped by a wooden toe rail. There is space below the toe-rail to the deck on one side and the hull on the outside and I think I could seal these areas fairly easily with caulking. So my questions are:
1. What is the best way to clean out the area to be caulked? Scrape with a pointed tool and wipe with some kind of solvent?
2. What is a good caulking product to use here?

Some of the leaks may be at the stanchions or the fairleads but I would prefer to do the toe-rail this summer and wait till next to try to get at these other areas.

If someone else has asked a similar question, just point me to the thread.
Regards,
Ross

cghubbell · #2 09-09-2011

It depends heavily on what the joint was initially sealed with. If it's butyl, then a little scraping and some Mineral Spirits will solve world hunger. If it's 3m 5200 you're in for a world of hurt.

Typically, doing this job "right" entails removing the fasteners from the joint, prying it apart carefully, scraping, cleaning with solvent, and then re-caulking it with an appropriate material.

I tend to think that when doing this job (as described) it's one of the few places where I would go with 4200 rather than butyl, but I recognize there are other viewpoints. I was able to squirt the 4200 into areas I would not have been able to lay butyl when I did my boat's hull-deck joint. However, if you can get butyl in, it's the way to go.

Either way, you want to clean out more than just the outside visible edge - you want to get into the joint to some degree to clean it and re-seal it in an area where the decks will push together to form a gasket. Anything less might help for a little while, but is not likely to be a long term fix.

mitiempo · #3 09-09-2011

I agree with Chris above - not lifting and re-sealing the toerail is only a temporary measure. But for wood to deck 4200 or Sika 291 are the way to go - I wouldn't use butyl unless it was under hardware and could be torqued down enough for compression. I don't think you could with wood unless it was a heavy bowsprit or something similar.

RossC32 · #4 09-10-2011

Hi,
Thanks to both of you for your replies. At my level of shipwright ability removing the toerail (which I would have to do to get at the hull/deck joing) would probably result in irrepairable damage to the boat, me, the environment and possibly to world itself. I will stick with replacing the present caulking that exists in at the toerail/deck and toerail/hull joints. It sounds like 4200 is the material of choice here, but what kind of "solvent"? Just the stuff from a hardware store labelled Solvent? Or mineral spirits or...?
Again, thanks for your replies and if anyone else wants to add anything, please do.
Cheers
Ross

cghubbell · #5 09-11-2011

Hard to say conclusively without really seeing the joint you are dealing with. It may be sufficient to VERY carefully use a utility knife to slice out a "V" shape in the joint, then scrape out the upper part of the v. After that, use acetone to clean the new gap. Finally, tape off the edges of the gap and put in the 4200. Use a putty knife or your finger to tool the joint smooth.

Given the length of a hull-deck joint you may want to consider injecting it with a caulking gun, but keep in mind that 4200 is VERY thick stuff and you'll want a good quality gun with some leverage - not one of those cheap ones that looks like stamped sheet metal. You will cramp your hands quickly trying to use the cheap guns. The good ones usually have a molded semi-ergonomic grip and are much heavier duty (but still available in most home stores).

Also, try not to do it when its really hot out as this will make the 4200 cure faster, and you want it soft as long as possible.

Hope this helps!

mitiempo · #6 09-11-2011

The best caulking guns are electric. Once you use one you will never go back.