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First time with Butyl Tape


freewheelin

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This will sound dumb, apologies. I am re-bedding a port light for the first time. I am using Life Safe Butyl tape. I looked through threads here and videos, but want to make sure I am not missing anything. I remove the mechanical fasteners, remove the existing silicone, clean with denatured alcohol and dry, line the port light with the butyl tape, and re-fasten the mechanical fasteners.

Is it really that simple? Do I need to add some silicone to the seal?

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No need for silicone. However, you should countersink the fastener holes in the fiberglass so the butyl will fill the countersink around the fasteners.

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No need to add silicone to the seal.  What does matter is to be neat/careful with the seams.  Butyl works by ""expanding" when compressed.  If your seams are not reasonable tight, its possible that you leave a path for water to get in.  A little thought about what direction the seams run (not vertical in this case) and nice clean cuts with a sharp knife/scissors will make sure you don't have an issue.  Same goes for the "holes" for where the mechanical fasteners pass thru.  As I recall from doing this years ago on our First 30E, you have "barrel bolt" fasteners right?  Again, if I remember correctly, I lined the portlight with the tape, then I used a long skinny xacto knife to cut an "X" thru the tape for each fastener, then cut the triangular tabs off, so that the hole was slightly smaller than the diameter of the barrel nut...took a little time, but didn't leak a drop when Hurricane Isabelle came thru Annapolis back in 2004.

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yes, barrel bolt fasteners. good memory! Ok, all of this seems to make sense to me so far. be careful with the seams, "predrill" a smaller hole for the fasteners, and countersink so the butyl fills. Thanks for the advice.

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First time with butyl?  Trust me, once you use this stuff you'll never go back to tubes of goop again.

The shit lasts forever, is clean and easy to apply (once you learn the proper techniques) and easy to disassemble and clean out, if you need to. There are only a small handful of applications where goop from a tube is the more proper sealant, such as through hulls below the waterline, but only a handful.

Also, the quality of butyl matters. Don't just buy the black shit from the auto parts store, buy the right stuff from Maine Sail.

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On 3/15/2019 at 7:27 AM, Ajax said:

First time with butyl?  Trust me, once you use this stuff you'll never go back to tubes of goop again.

The shit lasts forever, is clean and easy to apply (once you learn the proper techniques) and easy to disassemble and clean out, if you need to. There are only a small handful of applications where goop from a tube is the more proper sealant, such as through hulls below the waterline, but only a handful.

Also, the quality of butyl matters. Don't just buy the black shit from the auto parts store, buy the right stuff from Maine Sail.

What he said.

have some on my boat from 33 years ago that is still pliable..

Most important, get the good stuff from Maine Sail!

White stuff used to patch mobile home roofs is rubbish in a marine application too.

Ask your buddies if they want you to pick up some up for them too.  The shipping was pretty steep for a single roll  I purchased the other day.

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On 3/16/2019 at 10:52 AM, Foreverslow said:

What he said.

have some on my boat from 33 years ago that is still pliable..

Most important, get the good stuff from Maine Sail!

White stuff used to patch mobile home roofs is rubbish in a marine application too.

Ask your buddies if they want you to pick up some up for them too.  The shipping was pretty steep for a single roll  I purchased the other day.

@Foreverslow Do you have a link to maine sail?

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Didn't I read somewhere that you can't just crank down on the fasteners and leave it at that? Something about taking a few weeks to gradually tighten them down to prevent the stuff from thinning excessively under pressure. 

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It does need to be re-tightened, though not to prevent excessive thinning. The issue is that it cold flows (if you consider it a solid) and when it does so, it relieves the clamping pressure. In principle, you need to re-tighten to increase the pressure on the seal again. I've found that it's pretty forgiving about re-tightening if you start with clean surfaces because the butyl makes a nice adhesive bond and doesn't rely solely on clamping pressure to keep the water out like a rubber gasket would. One or two retorques does the job unless you used a really thick layer in the cold. When summer comes, you'll squeeze out a lot of excess.

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FWIW, I rebedded my 4 bow pulpit legs with Bed-It yesterday - went pretty well.  First shock was the amount of crud under the legs, grey powder, some flakes of caulk and a little rust staining.  Took more time cleaning that up than anything else.  There was some stuff very stubbornly stuck to the bottoms of the leg flanges, I sanded on it for a bit with a 150 grit sponge-block, some stuff came off but most of it was textured from the non-skid it had cured against and remained stubbornly attached - I figure the butyl rubber should attach to it just fine after it was washed and dried.

Some holes were already a little counter-sunk, I touched them all up to a uniform countersink that didn't quite reach to the balsa layer.

The sun was out, mid 70s but warmer on deck, and the rubber was pretty sticky.  I re-used the 1/4-20 stainless hardware and fiberglass backing plates, my wife torqued down with an electric impact driver from above while I fitted the washers and nuts and held fast with a wrench below - crud in the hair and a pain in the back getting to the front legs, but otherwise pretty easy.  I was worried about the jagged edges of my strips I was laying down, but they all contoured nicely around the flanges pretty well after the outflow from tightening.  Children on today's trip picked away the soft rubber around one flange, but that's not really the part that does the work - I hope.

So far, so good - rain for the next 72 hours should tell the tale of what else is leaking - a good jet from the hose didn't see any water intrusion around the pulpit legs, and they were a major source before the rebedding.

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5 hours ago, Fleetwood said:

Better to hold the screw from above and tighten the nut, to avoid rotating the screw/butyl joint and starving it.

Yes, better, and also incompatible with the impact driver due to access limitations.  I might have fit a ratchet and socket underneath, but there is maybe 6" of clearance side to side in which to work a ratchet.

All in all I think it's better done as is than not done waiting for perfection.  Mainesails' BedIt was flowing pretty well out everywhere.  Time will tell, but for now the rain inflow is stopped, at least around the pulpit legs.

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On 3/29/2019 at 12:32 PM, freewheelin said:

thanks for all the advice. I had already bought this stuff from defender when i started the thread. https://www.defender.com/product.jsp?path=-1|10918|2303278|2303279&id=1983369

Hoping to re-bed this weekend if the weather holds. 

there's no doubt that maine sail has a great product, but I've used the defender product with great success as well. you won't be disappointed.

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