What NOT to bed with butyl tape?

[Suijin]

OK, so Mainesail says that he beds 80% of his deck hardware with butyl tape and that's my plan when everything goes back on during my refit.

That begs the question of, what not to bed with butyl tape, why, and what to bed it with?

Discuss.

[Copacabana]

Suijin, I have become a big fan of butyl tape over the years. It never dries out, remains flexible and, being quite soft, really deforms to form a water-tight gasket. If one day you decide to remove the hardware, the butyl doesn't hamper this, unlike an adhesive or glue like 5200. That said, it has a few minor drawbacks. Obviously, it can only be used with hardware that is bolted on (it isn't an adhesive). It can't be used below the waterline (or so they say, although I bet it would be fine). The main problem with butyl is that it will ooze out from the sealed surfaces for quite some time. Normally for months after using it you have to go along and remove the excess from around whatever you sealed. A little piece of butly dabbed against the edge usually lifts it off (or you can use a plastic spatula). So, for a time anyway, there is some unsightly grey stuff oozing out from deck hardware. It's something I'm more than prepared to accept in light of the many positive qualities of butyl.

[Suijin]

Originally Posted by Copacabana

Suijin, I have become a big fan of butyl tape over the years. It never dries out, remains flexible and, being quite soft, really deforms to form a water-tight gasket. If one day you decide to remove the hardware, the butyl doesn't hamper this, unlike an adhesive or glue like 5200. That said, it has a few minor drawbacks. Obviously, it can only be used with hardware that is bolted on (it isn't an adhesive). It can't be used below the waterline (or so they say, although I bet it would be fine). The main problem with butyl is that it will ooze out from the sealed surfaces for quite some time. Normally for months after using it you have to go along and remove the excess from around whatever you sealed. A little piece of butly dabbed against the edge usually lifts it off (or you can use a plastic spatula). So, for a time anyway, there is some unsightly grey stuff oozing out from deck hardware. It's something I'm more than prepared to accept in light of the many positive qualities of butyl.

Yes I'm familiar with it's virtues and have used it in the past. I'll repeat the question, is there anything on the deck that you would not bed it with, why, and what would you use instead?

[Copacabana]

Originally Posted by Suijin

Yes I'm familiar with it's virtues and have used it in the past. I'll repeat the question, is there anything on the deck that you would not bed it with, why, and what would you use instead?

Sorry, I guess I didn't make myself clear ... I'd bed anything on deck that is bolted on with butyl, with no hesitation.

[CarlF]

I use butyl on any anything that penetrates the deck, wrapping screws so that the butyl extends about 1/2" below deck surface (and slightly chamfer the hole).

I'd be interested in opinions about bedding the entire fitting. When I used to use caulk, I would caulk the entire base of whatever I was mounting. Lots squeezed out and made a mess. Worse, when I remove old fittings it seems that this seal often partially fails and there is evidence of trapped moisture under the fitting (even if no water leaked through the bolt holes). So my new practice is just to seal the bolt holes. The risk is that it might allow crevice corrosion on the underside of the fitting. Thoughts?

[appick]

I don't know of any reason not to use butyl other than on fittings that will regularly be exposed to fuel or solvents. I've found that even the hardware store butyl tubes of caulking used for flashing siding work great and come in white. However they are.much messier than the tape.

[CarlF]

Has anyone tried butyl on chainplate deck penetrations?

There's no real mechanical seal beyond packing it in with a screwdriver blade. But it would seem to be well suited to the movement at this spot that causes regular caulk to fail.

[Suijin]

Originally Posted by CarlF

I'd be interested in opinions about bedding the entire fitting. When I used to use caulk, I would caulk the entire base of whatever I was mounting. Lots squeezed out and made a mess. Worse, when I remove old fittings it seems that this seal often partially fails and there is evidence of trapped moisture under the fitting (even if no water leaked through the bolt holes). So my new practice is just to seal the bolt holes. The risk is that it might allow crevice corrosion on the underside of the fitting. Thoughts?

Mainesail has a tutorial on his bedding technique and advocates bedding the entire bottom surface of the fixture. Excellent article BTW:

Re-Bedding Deck Hardware With Bed-It Tape Photo Gallery by Compass Marine How To at pbase.com

[Suijin]

Originally Posted by CarlF

Has anyone tried butyl on chainplate deck penetrations?

There's no real mechanical seal beyond packing it in with a screwdriver blade. But it would seem to be well suited to the movement at this spot that causes regular caulk to fail.

That is my plan.

My chainplates, which I just pulled, were bedded with 5200. While it had kept it's seal with the surrounding deck opening and core, it had separated from the chainplates themselves in some spots due to flexing.

The problem with a curing caulk is that once it cures, if it comes separated from a surface it's done. Butyl never cures so remains tacky and so short of contamination of the fixture surface will potentially rebond. It's also much easier to renew if necessary.

And there is a mechanical seal, it's just not a glue. The grey stuff is relatively sticky. The black stuff is almost impossibly sticky and working with it on a hot day maddening. I keep it in the fridge until the very moment I need it. Even then a few minutes of contact with my fingers and it's not coming off except with mineral spirits.

[appick]

On a side note have you ever tried to contaminate the stuff? From my experience you can't! Bits of dirt and debris just get swallowed by it and it keeps on sticking.

[Suijin]

Originally Posted by appick

On a side note have you ever tried to contaminate the stuff? From my experience you can't! Bits of dirt and debris just get swallowed by it and it keeps on sticking.

Yeah dirt just gets amalgamated into it but that can only happen up to a certain point, I think. If you get continual contamination into a joint eventually the butyl is going to be stuck all to dirt and not to the fixture. Not an issue in fixtures that don't flex but chainplates do, so vigilance and periodic inspection are pretty key to keeping the seal maintained.

[Tessellate]

To answer your question, I would not use butyl on anything that you physically can't get the butyl into very well. For example, awkwardly shaped things, or perhaps chainplates that don't have a coverplate. If there isn't something to compress the butyl with, it may not form as good a seal as a goopy sealant that can flow around the part.

Also if you require strong adhesive properties (load bearing) and the item isn't thru-bolted, then don't use butyl. This is uncommon on well designed boats because something that needs to be strongly attached should usually be thru bolted.

[EmeraldCoastSailor]

Originally Posted by CarlF

Has anyone tried butyl on chainplate deck penetrations?

There's no real mechanical seal beyond packing it in with a screwdriver blade. But it would seem to be well suited to the movement at this spot that causes regular caulk to fail.

I used butyl on my Beneteau chain plate arrangement. Almost two years ago and so far so good. I used it liberally and was trimming excess for several months but a trivial issue for the value.

[mark maulden]

Originally Posted by CarlF

Has anyone tried butyl on chainplate deck penetrations?

There's no real mechanical seal beyond packing it in with a screwdriver blade. But it would seem to be well suited to the movement at this spot that causes regular caulk to fail.

I use it on chainplates. Mine stick up through the deck and I've used polysulfide and would have to redo every yr depending on boat usage. Every time I was out of town, I'd wonder if they were leaking. Take some tape and roll into a cylinder bigger than the gap and lay it in all around. Then take some flat and lay it over the stuff you just packed in. Take anothr flat and lay it next to the plate so some of it goes up the plate. Wrap the dck plate screws and install. You can knead the butyl around the chain plateand all around between the deck plate and chain plate. If you still have have more room between the deck plate and chain plate, just knead in some more butyl. Mine have not leaked in 3 yrs since doing this. There are no real compression forces but it seems to work since butyl sticks to everything...

[Copacabana]

Originally Posted by EmeraldCoastSailor

I used butyl on my Beneteau chain plate arrangement. Almost two years ago and so far so good. I used it liberally and was trimming excess for several months but a trivial issue for the value.

This seems to be the only real drawback with butyl- the excess that keeps oozing out. Even a year after applying butyl I find myself removing a bit of excess on an especially hot day.