Help please from Butyl Tape experts on rebedding

[Frank Langer]

hi,

I have read the various posts on rebedding deck fittings with butyl tape. I very carefully rebedded several stanchions with butyl tape--cleaned the area thoroughly, placed a 1/16" base of butyl on the deck under the stanchion base, wrapped each of the bolts in butyl tape "worms", etc. A few days later, I noticed that the tape had oozed out a bit further from the base of the stanchion, so I trimmed it back flush, and was able to tighten the bolts a bit more than when I had done it a few days before--they had been tight then.

Today, to my dismay, I noticed that the teak inside the cabin underneath the stanchions was wet, so clearly they are leaking. I am tempted to abandon the butyl tape and try 4200 or similar caulking material, but the butyl tape was so nice to work with, and others have spoken so highly of it, that I am asking for any advice or tips that might explain why the stanchions are still leaking and what I can try next.

Any comments or advice is welcome.

Frank

 

[mherrcat]

This is a dismaying development. I don't remember where I read it, probably a Maine Sail writeup, but in cleaning the surfaces to be sealed removing any trace of silicone residue is very important; even to the point of wet sanding the surface. Acetone, lacquer thinner, etc. are not enough.

I did some wet sanding when using butyl to rebed my original windows and did notice that the butyl will not stick if there is any silicone residue. Maybe that is what happened and water was able to get in?

I haven't had any problems with the rebedding job that I did on my windows several months ago. The butyl did ooze out for several days after bedding and I have noticed that even a little more has squeezed out over time; probably because of softening due to heat from sunlight.

 

[tenders]

Butyl is a simple, forgiving material...if it looks like it's sealing, it's probably sealing.

Are you positively certain that the core through which you're running the fasteners is bone dry? It's possible that the water is coming from the inside, or elsewhere on the boat, rather than from the outside. And if you're able to tighten the fasteners after a few days, it may not be due to the butyl tape - it could be because the two layers of the hull are flexing (again possibly due to wet core).

 

[Emerald]

I would agree to look at surface contamination that kept the butyl from sealing properly or water moving through the core from somewhere else. Have you disassembled one to see how the butyl stuck? Regarding the oozing at the edges, if this is bothersome, you can put a small bead of another caulk around the item to keep the butyl in. Something like 3M's 4000 UV, which doesn't yellow, would be a good candidate.

 

[Maine Sail]

Butyl is a simple, forgiving material...if it looks like it's sealing, it's probably sealing.

Are you positively certain that the core through which you're running the fasteners is bone dry? It's possible that the water is coming from the inside, or elsewhere on the boat, rather than from the outside. And if you're able to tighten the fasteners after a few days, it may not be due to the butyl tape - it could be because the two layers of the hull are flexing (again possibly due to wet core).

This is very often what happens. With a quality butyl you MUST make multiple small tightenings allowing the butyl to compress slowly and the excess to ooze out at it's own rate. Tightening all at once is not good as a good quality butyl has a fairly high durometer rating. Due to this density you can compress the deck before the butyl if trying to do this to fast.

As mentioned the deck and fittings need to be 100% clean and free of all contaminates.

I would be very surprised if your water came from the bytyl side. My guess is that it came from the deck or another leak in the boat that "escaped" through channeling at that particular stanchion. Very often "leaking" hardware is not the "leaking" hardware but rather the exit point for a leak elsewhere. You could also be compressing a damp core and squeezing it out like a wet sponge.

 

[Loren Beach]

I generally agree with both Tenders and Maine Sail.
One caveat is to invoke the spirit of Occam's Razor -- and be sure that a deck leak that appears after your resealing work is a "new" or "old" leak.

Lots of rain in the NW lately; was there either a rain event or was the deck washed down right after the stanchion was rebedded?

Was the teak inside showing any sign of seepage prior to the rebedding?

BTW, the advice about slow compression of the butyl is right on. That stuff will compress (very slowly) until hard surfaces on both mating parts limit the process.
*(Prior boat story) I was still removing a small bit of butyl "seepage" from under the factory toe rail 12 years after my Niagara 26 was constructed.
No leaks, though!

Cheers,
Loren