Butyl Tape in Tropics

[delmarrey]

Project Boat Zen - Understanding and Using Marine Sealants

Cons
Cannot be used underwater, Paint will not adhere to it, Will support mould and mildew growth, Short tack free times mean you must work fast on larger projects, Low tear strength, Poor abrasion resistance, Harder cleanup (leaves film) does not sand well.

Now, why would I want to use it???

[sailvayu]

Pros
Ease of use, Fast cure, Long life, Good Flexibility over its life, Comes in many colors including clear, Inexpensive, Non Toxic once cured, Excellent UV and weathering resistance, Good resistance to chemicals, oils, and high temperatures, Long package life even once opened, Low shrinkage rate, Large gap filling, Non acidic type good for sealing electrical connections, Can be applied in a wide range of temperatures.

Come on why just quote the negative

[Blue Stocking]

Must be a slow Saturday

[sailvayu]

Must be a slow Saturday

LOL I am installing a new dinette table while doing this! got to have fun somehow lol

[Maine Sail]

Cheaper grades of butyl, like the RV or roofing grades, will ooze worse than quality butyl tapes. Black can bleed and be messier than gray but if "properly" bedded and torqued down correctly, meaning multiple small tightening events, the butyl will not ooze, or very, very minimally. 80% of our 1979 boat is 100% un-rebedded. She's bone dry and was factory bedded with butyl tape in 1979...

Even the chain plates had not leaked a drop in 31 years. I removed them to inspect and replace if necessary seeing as the PO never had. They were in pristine condition and bone dry even after 31 years and over 50k nm. Five years of her life were spent on a world cruise much of the time spent near the equator..

The idea that all the butyl will squish out and the fitting will leak is completely un-true if bedded properly with a good quality product.. Bone dry decks & fittings even at 32-33 years are not uncommon with butyl.

This piece of Lexan was drawn tight enough to snap a 1/4 X 20 SS bolt. There has been no more "oozing" of this test fitting in the four years since I did this and it has been stored in the top floor of my barn which regularly hits 140+ degrees in the summer heat due to the black roof.



This is how I bed with butyl tape:

Bedding With Butyl Tape

[minaret]

Personally I don't think oozing butyl is acceptable on a "bristol" yacht. Hence the suggestion to only use butyl for fasteners or in the center of a piece of hardware and finish with a bead of sika or 4200 around the edges. However, I actually do use a ton of butyl on my boat. I use it to fix in place everything belowdecks which I dont want to move on me. Computer monitors, speakers, art work, all sorts of stuff which I don't want to drill some holes in my priceless bookmatched teak to install. If you use the good butyl made for vacuum bagging, which I always have a surplus of from work since we go through a few cases a year, it holds amazingly well. On my last boat the main table in the saloon was bonded to the sole with a spiral of butyl. I'm a big guy but I could stand on it without it moving at all. I've never even pulled any varnish removing something I butyl'd in place, a perfect compromise for me....

[sailvayu]

Mainesail

With all due respect your test is not really valid as example as most boats do not spend their life in a barn protected from sun and rain. As a heat test yes it does prove something.

Now I am not saying butyl should not be used I have seen it used in many places effectively, the poster who said hull deck joint is a good example. Builders use many different sealants in different places for different reasons. I am just saying for bedding most deck fittings I think silicone should be considered.

Just because one type of sealant works in one place or use does not mean it is good for everything. I agree butyl for chainplates and windows is a good use but to install a cleat or stanchion no. As for hull deck joints there are now much better product such as methacrylic adhesives.

[s/v Jedi]

I will not start about solid neoprene gaskets again, so it's about a polysulfide this time

I prefer polysulfides for bedding anything that has mechanical fasteners, i.e. 3M 101 or BoatLife LifeCalk. I had to remove a huge stainless piece of gear from the bow that had been there for 15 years and it came off easily, with liquid 3M 101 in the center still (it cures with moisture).

The best way to use this is in a combination of cured and fresh sealant. You can put a little bead (in any shape/figure you like: square, round etc. to fit the flange) on some scrap and let it cure, then use a razor knife to cut it off. Put that between the hull and fitting as a spacer so that not all liquid sealant that you add will be pressed out. Tighten fasteners a bit so that fresh sealant shows a bit all around and let cure 24 hours. Torque fasteners to spec after that. Cleanup is the easiest of things with polysulfate: just cut around the fitting and use terry shop cloth to mechanically remove it.

Also: countersink the holes for fasteners so that sealant forms a gasket there.

ciao!
Nick.

[sailvayu]

Nick I agree with the counter sink around the hole. I use a O ring around the fastener that seems to work well and is fast, it fits into the counter sink nicely if it is shallow and will compress as the fastener is tightened.

I do not like to cut cured sealant because it can score the gelcoat and cause hairline cracks, also it can leave a sharp edge for water to get started into. I like a little fillet to keep water out

The home maid gasket sounds interesting but I am guessing you have more free time than I do lol I am always in too much of a rush for that type of thing but does sound like it would work.

I have never had much luck with Neoprene gaskets, they tend to get hard after a few years and start to leak. But I have not tried them in a long time and maybe the rubbers are better these days

[s/v Jedi]

Originally Posted by sailvayu

I do not like to cut cured sealant because it can score the gelcoat and cause hairline cracks, also it can leave a sharp edge for water to get started into. I like a little fillet to keep water out

I also dislike cutting it and actually use a spudger for this... but I'm afraid nobody knows what that is

The home maid gasket sounds interesting but I am guessing you have more free time than I do lol I am always in too much of a rush for that type of thing but does sound like it would work.

Upkeep of the boat is my complete job description I copied this method from the Sikaflex instructions for glazing jobs. You can pre-make these by the cartridge if you like... it's just a bead, for spacer, nothing like real gasket shape needed.

I have never had much luck with Neoprene gaskets, they tend to get hard after a few years and start to leak. But I have not tried them in a long time and maybe the rubbers are better these days

I have it behind my chainplates, which were put on in 1993 and I can't improve it even today 18 years later. I'm sure it has to do with type/quality of the rubber. I always have some 1/8" and 1/16" thick around:


ciao!
Nick.

[Blue Stocking]

I owned a commercial glass and aluminum company. Those millions of square feet of highrise glass you see are often bedded on butyl tape-the good stuff, and squeezed in place by 1/4" thick aluminum pressure plates, fastened with 1/4 x 20 machine screws every 3"
. And usually require a 20yr guarantee against failure

[Maine Sail]

Originally Posted by sailvayu

Just because one type of sealant works in one place or use does not mean it is good for everything. I agree butyl for chainplates and windows is a good use but to install a cleat or stanchion no. As for hull deck joints there are now much better product such as methacrylic adhesives.

Funny every CS boat built except for some later models had all deck fittings bedded with butyl tape. On the CS list we rarely discuss wet decks or re-bedding. I find stanchions are one of the best places for it especially if you have those floppy plate stanchion bases. I've yet to rebed any stanchion I have ever sealed with butyl tape. Our deck cleats have been through five hurricanes and multiple Nor' Easters. Still bone dry and un-rebedded at 32 years.

No bedding compound is perfect and I still use all the others, including silicone, where applicable.

Butyl also comes apart and cleans up far easier than any of the other sealants, especially silicone, which is nearly impossible to remove the embedded residue.

[Maine Sail]

Originally Posted by sailvayu

Mainesail

With all due respect your test is not really valid as example as most boats do not spend their life in a barn protected from sun and rain. As a heat test yes it does prove something.

That example was only to disprove the theory that when you fully tighten a deck fitting with butyl that it will simply squeeze out and nothing will be left. I broke a SS fastener tightening and it still never squished it all out..

I'll reserve my vessels nearly 33 year history of bone dry decks while 80% of the boat has yet to be re-bedded, and it's not spent its life in a barn....

[Maine Sail]

Originally Posted by s/v Jedi

I prefer polysulfides for bedding anything that has mechanical fasteners, i.e. 3M 101 or BoatLife LifeCalk. I had to remove a huge stainless piece of gear from the bow that had been there for 15 years and it came off easily, with liquid 3M 101 in the center still (it cures with moisture).

I too was a HUGE fan of 3M 101 but the execs at 3M decided to discontinue the product..

If you liked 3M101 you might try Sikaflex 295UV which is a low adhesion polyurethane that holds up to UV well and remains pretty flexible....

[s/v Jedi]

Originally Posted by Maine Sail

I too was a HUGE fan of 3M 101 but the execs at 3M decided to discontinue the product..

If you liked 3M101 you might try Sikaflex 295UV which is a low adhesion polyurethane that holds up to UV well and remains pretty flexible....

They did?! Wow, probably too cheap and simple a product for them, like butyl

But LifeCalk is the same thing, I have changed to that because the tubes are easy to get, so never noticed 3M 101 being discontinued

I am not a big fan of polyurethanes but use 5200 now and then. The 295UV is used for my pilothouse windows. Renewing those is a sore spot on my list still....

cheers,
Nick.