Best Butyl Tape For This Job?

[Madehn]

So i am in the process of replacing the large windows in my Gulfstar with 1/2 inch real safety glass as the old stuff was badly crazed and fogged-- i have one side out and are working on fixing all of the stress cracks etc that come with having an older boat. i planned on using butyl tape when i put the new windows in but got to wondering if all butyl tape is created equal i suspect not - how do you tell the really good stuff from the run of the mill? Cost is really not a consideration as i want to do this job once and have it last for a long time.
The other question was is butyl tape the right product to use for this? Is there something better? The way the mountings for the glass are there is no need for adhesion just for sealing.

[LLCoolDave]

MaineSail is a member here. He has lots of great how to articles. I've heard his butyl tape is the best but haven't used it myself.

https://shop.marinehowto.com/products

[john61ct]

The best, from our Maine Sail

http://shop.marinehowto.com/products/bed-it-tape

Edit: jinx!

[PLANET EXPRESS]

https://www.amazon.com/3M-08609-Wind...95050258&psc=1

[john61ct]

And it is possible this **one** use case glazing, is like the only one where sillycon is appropriate

But I'm sure others will have comments and better suggestions on that

[ontherocks83]

I'm not sure if these are the type of windows you have, but here is one possible option. I found this channel a few months ago and it has become one of my favorites. He is a little quirky but I find his channel very informative for boat repairs! Hope this helps.

https://www.youtube.com/watch?v=MQyjxVUskd8

[Reefmagnet]

Butyl mastic is great for window sealing. I've used the stuff designed for sealing car and truck windows in the past for boat windows. Has no holding strength and is non hardening. It's supplied in a regular caulking tube and is black, too, which may hide it a little better

[jooa]

Butyl also comes in tape form. There are at least 3 that I am familiar with black, grey, and white, all of which come in a variety of widths and thicknesses. The tape is very easy to handle, just peel off as much as you need and have at it.



The black butyl can stain white fibreglass but works well in situations where you might have very dark windows or the the boat was originally trimmed out with black chaulk/sealant. It is easy to handle, clean up (except for the possible staining), stays flexible forever, easy to store and seems to have no expiry date.



I find the grey to be the most compatible with many boats as it is fairly neutral in color, seals exceptionally well, stays flexible forever, is easy to use and easy to clean up and wont stain surrounding material.



The white is to be avoided at all cost. You may think that it will blend in well with your white gelcoat, but the down side is that it breaks down very quickly in the marine environment.





Butyl is not an adhesive! It must be used in conjunction with mechanical fasteners. Butyl is my #1 go to when attaching most hardware that is mechanically fastened to the deck. The hull deck joint on my 41 year old CS27 is sealed with grey butyl and is still soft and flexible and doing its job exceptionally well, as are my window lights, shroud plates, chainplates, primary forward cleat, and assorted other hardware. Also, butyl can be broken down with some solvents/petrochemicals, so do not use it on your fuel fill!



I live in Vancouver and have bought butyl tape at auto supply stores, usually the black. I have found grey at glass/window/mirror supply stores. The stuff is cheap, like $10.00 for a roll which will last you forever. It's great stuff on a boat.

[CarlF]

If going with Butyl definitely use MainSail's version recommended above. If you've never used it, buy some just to have aboard. Lasts forever on the roll and useful for many things.

The challenge with Butyl is you need a lot of clamping force. Does your window frame have a lot of screws so that the butyl with be compressed over its entire length? You should tighten the screws for several days to keep pushing it down.

If you may not be able to get enough clamping force, consider Dow 795. The stuff is designed to hold windows on skyscrapers. Adheres tenaciously to metal, fiberglass, glass and plexi. No UV color change. Much neater to work with compared to most adhesive caulk. Smooths nicely with a small putty knife and gloved finger. Very strong.

But the trick with 795 is the bead must be at least 1/4" thick to be flexible enough to handle expansion/contraction. It shouldn't be all squeezed out. One trick is to use a 1/4" thick foam tape at the edge to act as a spacer while the 795 cures. Or use 3M VHB 4491 tape as both a spacer and an adhesive along with the 795.

[sailortype]

avoid the black auto butyl stuff... works well but what a mess it makes if you get any on your gel and it will be a permanent stain. I know this : |
Also best to avoid silicone based sealants because nothing will ever stick to the gel again where it is used. Dow has some good goop for this, also one of the many polysufides. But butyl works well, easy to use and redo if you have to, and as long as you have compression you will have a good seal.

[doublewide]

my 2-cents-worth:
I would always follow the instructions given by the boat manufacturer or the window manufacturer if available
Having said that, I am a huge fan of butyl tape for caulking any joint that derives its mechanical strength from some fastener other than the caulk.
If the caulk also needs to be an adhesive, then butyl tape won't suit the job.
As proof of efficacy, auto manufacturers use butyl tape for windshields, and they never leak even after 20 years.
I have bought black butyl tape from the auto parts store and it caulked fine, but it was sticky and hard to clean up.
Better was the gray-colored butyl tape I bought from Sailrite. It cauked very well and was exceedingly easy to handle, and easy to clean up after the job, using the "bubble-gum technique." Just dab at any squeeze-out using a little lump of butyl, and it cleans right up.

[Dash-Robo]

I am rebuilding 4 by Lewmar Superhatch 30 plus years old
the butyl tape was still flexible and easy to remove, found that the silicon seal areas were zinc chromate protected to inhibit corrosion (some silicons have an acid content )
I had the hatches surrounds anodised to protect against corrosion and toughen the surface ,anodising is an inexpensive process and for hardness is second only to diamonds
Many hatch repairers use new technology ,non acidic sealants and packers they no longer use buytel tape. I looked at the revised process decided to stay with the original assembly method as the butyl tape is easier to bed the lens into and has a consistent height, Tip for final finishing of the outer seals tape edges or use existing paper film and chamfer the lens edge makes it easier to remove and produces a nice clean edge
If possible fit the frame to the lens not the lens to the frame . Best elevate lens and lift frame to fit the lens

[AKA-None]

I’ve tried the hardware store stuff of various types but the sailrite butyl ended up as the best seal. I’ve since replaced all the other products with that and am well pleased.

[skipgundlach]

I have used Dow 795 for bedding non-glass plastic lenses. It's the bee's knees. Available in black, gray and white. Here's the aft hatch lens - from - solid change we did:

Pictures: Flying Pig 2011-2012 Refit/Aft Hatch Glass

Note the first subgallery - prep is key; we'd misread the instructions and used the cleanup, not cleanER, stuff, and the first attempt never set. 6 years later after the redo, it's perfect, still, and I expect it will be, for however long the plexi lasts.

Rod Collins (Mainesail) will tell you that curved surfaces (surely not with actual safety glass) are not appropriate for the tape, and while it CAN work, having a bolt which you can secure from turning while tightening the nut will give you the best results, rather than a screw, which MUST turn to tighten (and may not be able to exert the force needed to fully bed it, whereas the 795 should have spacers to insure adequate expansion/contraction space)...