To Butyl or not to Butyl

[KenH]

Looking for some help from the knowledge here.

I need to re-do my Portholes and was thinking about using Butyl tape.
I would like to use Black or White to try to match the Hull or have the ring just look more solid.

I was going to go with 1-1/2" wide and cut the extra off.

Do you guys think this would be a viable way for just plex Portholes?

Here is a picture so you can get the idea.

[Hartleyg]

It should certainly seal the port. Keep in mind that the butyl will ooze out some when you tighten down the screws - and it will continue to ooze as long as there is pressure, so you may have to "clean up" several times before it stabilizes.


Hartley
S/V Atsa

[stainless guy]

If it were me I would mask and paint the backside of each porthole to match the opening to hide the inconsistencies of the butyl

[S/V Illusion]

There is a butyl tape which comes in various widths and thickness which avoids the messy liquid type. On another forum I frequent, a guy there sells the stuff but it's nothing special despite his claims and can be bought at most hardware stores.

I have never used this stuff as it seems inherently a poor filler but it is an easy fix if it works.

[estarzinger]

3m VHB (very high bond) tape (double sided) is terrific for that application. you can get a wide range of widths and thicknesses.

[Bleemus]

If it is attached by screws you want an adhesive. Butyl if not an adhesive. If through bolted then butyl is fine.

[KenH]

Originally Posted by Hartleyg

It should certainly seal the port. Keep in mind that the butyl will ooze out some when you tighten down the screws - and it will continue to ooze as long as there is pressure, so you may have to "clean up" several times before it stabilizes.


Hartley
S/V Atsa

I figured I would have to clean it up here and there for a while..
Thanks

[KenH]

Originally Posted by estarzinger

3m VHB (very high bond) tape (double sided) is terrific for that application. you can get a wide range of widths and thicknesses.

I can get some, I just think it breaks down faster.

[KenH]

Originally Posted by Bleemus

If it is attached by screws you want an adhesive. Butyl if not an adhesive. If through bolted then butyl is fine.

I was thinking about changing from the bolts with Acorn nuts to screws that are shorter on the inside.
The thru bolts are a pain...

[philgiles]

Definitely the way to go. Butyl is also available in cartridges. Either tape or cartridge is OK. However, I have found that the black butyl stains the surface of the cabin side. The cartridge is easy to apply and excess wipes off easily and cleans up nicely with mineral turps. The screw heads should also have butyl applied and best to hold the screw heads to stop them from rotating whilst tightening up the nuts from the inside.


The butyl does not harden and so subsequent removal of the windows is a breeze.

[letoile]

I used it on a fixed hatch on my boat and it is bomb proof, no silicone required. A.few things I learnt when using it.
1. When screwing through it the screw will grab and.twist butyl around the screw. Thus punch a small screw sized hole through the butyl reduces the twisting.
2. Butyl will compress as.far as you drive the screw, thus a thickness spacer like a O ring of.the correct thickness around each screw will allow you to tighten the screws without totally compressing the butyl.
3.you can double it with thickness spacers
4. Put on enough width so it extends.past.the edge and.trim
5. I.found it cheapest to buy at RV stores.
Good luck!

[Locquatious]

Butyl strip caulk can be found in many RV stores. We have had success w/UV4000. Over time the butyl will weather and harden just like in old window frames.

When replacing the bolts, make sure you use bronze rather than stainless. The stainless will give up to bronze when clamped between bronze flanges. We lost stainless bolts in just a few years.

If there is wood between the bronze port flange and the hull fiberglass, ensure the wood is in good shape and even then coat the wood with epoxy resin to prevent water from soaking into the wood. The old wood becomes spongy over time. Just tightening the bolts rarely stops the leaking. Dig out the bad wood and replace it with epoxy. We make clear-box-tape molds held flat with clamped boards to contain the liquid epoxy till it hardens. The box tape will not stick to the epoxy. Usually the wood is good just up to the edge of the port flange so you never see the epoxy repair.

In some cases, where the ports were more exposed to sea water, we cut out all the wood that was clamped between the bronze port flanges and the hull fiberglass. We fabricated fiberglass rings to replace the wood and have had no leaks for 15 years.

The port seal is actually in the flange clamped portion and less so in the hull edge to port body region. You can usually get the caulk uniform under the flange but you are never sure you have the caulk fully between the hull edge and port body. Make sure you caulk the bolts when you put them in as this is a common leak path. It is doubtful that butyl caulk would seal the bolts as well as urethane caulk.

[Scaramanga F25]

Butyl is best for your application, re: your photo.

[EmeraldCoastSailor]

I have used the black stuff from auto parts stores and white stuff I got from Camper's World. The white stuff works great without the nasty black mess. You must have fasteners that hold things together as butyl isn't technically an adhesive, and you will need to tighten once or twice more after installation. I say technically only because all my applications using butyl are rock solid and involve plenty of stickiness. Still, you need fasteners. I think butyl would be a good fit for your situation.

[Scaramanga F25]

The Butyl ribbon that was used by C&C Yachts and Mirage Yachts on portlights was grey an is available in various widths and thicknesses at holland marine products.

1/8 in. thick X 3/4 in. wide. 15$Can. a roll. grey