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You can also purchase it at any heating and air conditioning (HVAC) supply store. We use it to seal high pressure duct flanges for an air tight joint. Grey in color.
 

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Here's why I like butyl tape

This is a cut-a-way photo i made of a section of deck that I first potted with epoxy then countersunk. I then wrapped butyl tape around the bolt head, tightened it down and left it there for a while. I then loosened the bolt and began pushing up from the bottom. There is no movement on a boat, with a mechanically fastened deck fitting, that will even come close to that amount of flex and stress on a sealant.

Remember this stuff has very low adhesive properties, unlike 5200, 4200 or any other caulk tube type sealant, and cleans up quite easily with paint thinner. Adhesion is not necessarily needed flexibility is! This stuff will out stretch and out flex any caulk tube sealant you can buy in a marine store..

Of course you must always bevel or countersink the deck side so you can fit more sealant in the gap. The more sealant the more allowable flex. If you look close you can see the beveled edge.

Yes I finally got sick of trying to describe the process of potting holes and countersinking so I took some pictures.

Stretch!


 

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Maine Sail-

Nice photo... :) very illustrative of the properties of butyl sealant. Glass shops usually carry it btw... but usually only in the black. :(
 

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Discussion Starter #24
A source for the grey butyl tape

I looked all over Long Island, calling a bunch of RV stores, and finally gave up. I ordered mine from The Sportsman's Guide (an amazon.com seller) for less than $10, shipping included.
 

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I use butyl tape while vacuum bagging. I get it from a roofing supply store. It is used on standing seam metal roofing to seal the seam between sheets. Much cheaper than the specialty vendors of bagging supplies.
 

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Butyl tape and visqueen beats tarps and tape for staying dry

We are currently living on a boat with all portlights and one hatch removed. Replacing them is taking longer than expected. Meanwhile, we've had sleet, snow, rainstorms, and temperatures in the 20's.

We are snug and dry, thanks to butyl tape and visqueen plastic.

Here's what we did: We cut a piece of plastic to fit over each opening. We formed a long skinny "snake" of butyl and put it around the perimeter of the plastic, then stuck it on. It's quick to put on and take off (we use a dull razor blade to get it started), so we can put it on at night and take it off while we're working. Unlike tape, it doesn't leave residue and we just keep using the same piece over and over.

This would work for just about any large opening or deck repair.

For small holes, just make a ball of butyl and stick it over the hole.

The only downside to this solution is that when you have hail, it's like living in a large, noisy drum! But it holds up just fine.
 

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I'll be re-bedding my bow pulpit soon and I have a question on the application of the butyl tape. Obviously it goes around the bolts as per Maine Sail's instructions.
But would you also cover the entire bottom of the plate base with strips of it? I don't see why this would be needed if the bolt holes are sealed with it. Your thoughts..
 

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Yes

Yes I cover the entire base of the fitting then tighten it down. It's best to wait for a hot day and the butyl will compress easier.. The problem with us NE boaters is that water can get under a fitting and expand and yuo don't want that so it's best to seal the entire base. Get the thin flat butyl tape. I think mine is 1/16" thick if I am not mistaken.
 

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Thanks Maine Sail. My tape is about the same. About 1/2" wide and 1/8" thick, gray. I can heat the surface and SS with a heat lamp before I pull everything tight with the bolts. I bed my topside teak hand rails last year and still had some squeeze out the joint during the summer. Easy to remove.
 

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I think the butyl I have is more like 1/8". I'd love it if it was 1/16" as half of it squeezes out--but at least at that point you can be pretty sure you've got a great seal there.

A couple of things about butyl I've found lately:

* When working on an overhead bolt that hangs straight down, a dot of butyl on a washer will hold it there temporarily while you are trying to get that nut on there.
* Mineral spirits gets it off your fingers and other surfaces if necessary. This is especially handy when your fingers have reached critical mass of stickiness, turning you into spider man.
 

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Yes I cover the entire base of the fitting then tighten it down. It's best to wait for a hot day and the butyl will compress easier.. The problem with us NE boaters is that water can get under a fitting and expand and yuo don't want that so it's best to seal the entire base. Get the thin flat butyl tape. I think mine is 1/16" thick if I am not mistaken.
I concur completely. I am on Lake Ontario, so while we don't have the salt, our freeze/thaw cycles are as brutal as Maine's if not worse (we are enjoying one today, for instance!).

I got hit at dock by a Peterson 37, the crew of which had loosened the nut on the wheel in preparation for a winter haulout...BEFORE they had motored there...anyway, one of my stern quarter extrusions had been bashed and needed to be removed for rewelding and anodizing. So when I got my wife back in the stern with a rachet and undid the afflicted piece, I noticed it was fully bedded in grey butyl tape.

My boat was 33 years old at the time, and this stuff was "live" in the sense of being seemingly fresh!

Not being one to argue with success, when I redid the job, I redid the butyl tape the exact same way, but with separately bedded and new bolts and fender washers. It looks great and there will always be a place aboard my boats for this half-forgotten but very versatile product.
 

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This butyl tape thread is very interesting. Last Autumn I removed my grab rails for refinishing (looked like they had not been removed since my Islander was built in 1984). Who put them on used something red that worked like glue (and is now hard as a rock). No clue what that was.

I've been wondering what to use to reattach my grab rails to the deck. What do you think? Is butyl tape the best product given the roughness of the wood?

DaCap
 

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I have a some questions about beveling. To create the bevel are you simply using an oversized drill bit to countersink or is there some other method? Having never drilled through gelcoat I am concerned about chipping.

Also, are you beveling all holes (including those under chainplates, stanchions, etc.)?

thanks!
 

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Yes, butyl tape should work quite well for you.
This butyl tape thread is very interesting. Last Autumn I removed my grab rails for refinishing (looked like they had not been removed since my Islander was built in 1984). Who put them on used something red that worked like glue (and is now hard as a rock). No clue what that was.

I've been wondering what to use to reattach my grab rails to the deck. What do you think? Is butyl tape the best product given the roughness of the wood?

DaCap
If you're using a good countersink bit, run it in reverse so you don't countersink too large a hole... It won't chip the gel coat if it is run in reverse either.
I have a some questions about beveling. To create the bevel are you simply using an oversized drill bit to countersink or is there some other method? Having never drilled through gelcoat I am concerned about chipping.

Also, are you beveling all holes (including those under chainplates, stanchions, etc.)?

thanks!
 

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Hm, I need to rebed my traveler and car tracks. I was going to use 3M 101, but it sounds like butyl will be lots easier. Thanks for the thread!
 

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So if the car track is 3/4 inches wide, is it best to use 3/4 inch wide tape, or 1/2 inch tape? I am guessing that when the bolts are tightened, the tape compresses and oozes out a certain amount...
 

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Use the 3/4" wide tape if you've got it... makes applying it simpler. Cleaning up butyl tape excess is really easy. :D
So if the car track is 3/4 inches wide, is it best to use 3/4 inch wide tape, or 1/2 inch tape? I am guessing that when the bolts are tightened, the tape compresses and oozes out a certain amount...
 

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Use the 3/4" wide tape if you've got it... makes applying it simpler. Cleaning up butyl tape excess is really easy. :D
Nah, I don't have any, i was about to order some and was trying to decide what size. I'll get some of each ;) At $3.50 a roll, ya can't have too much!
 

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Yes, it is probably the least expensive and most versatile of the sealants. As I said in my nutshell post, the fact that it doesn't have a cure time makes it very good for doing genoa tracks and traveller tracks... which are often long enough that doing it by yourself with a quick curing more adhesive sealant is a real PITA.


Nah, I don't have any, i was about to order some and was trying to decide what size. I'll get some of each ;) At $3.50 a roll, ya can't have too much!
 

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Nah, I don't have any, i was about to order some and was trying to decide what size. I'll get some of each ;) At $3.50 a roll, ya can't have too much!
Went by the local Marine store the otherday,and they have butyl tape, but it is $21/roll. Off to the RV Center one afternoon this week!
 
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