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which sealant to use

3K views 5 replies 3 participants last post by  LookingForCruiser 
#1 ·
Hello,

I have many things to seal. I wanted to both question, and verify, which sealant goes where.

1. Teak rub rail to fiberglass deck. This is polysulfide, such as Sikaflex or 3m 101, yes ?

2. Metal chock (is that how it is spelled) to wood - the wood is above the fiberglass, the metal chock sits on the wood so its above the rub rail, and is bolted through both wood & fiberglass. Is this polysulfide as well ?

3. Plastic to fiberglass. The stern light will be attached to the stern. It needs a wee bit of adhesive strength, as the mounting hardware for the Aqua Series 32 stern light is fairly wimpy. 3m 4200 yes?

4. Metal bolt to nylon antenna mount that is 5200'd to the fiberglass. Well I have a big 8' VHF antenna off the stern of one of my hulls, and the antenna mount was broken during shipping. Undid the bolts, and went to remove the mount. Surprise! it's attached with 5200. Joy. I found an identical mount, and was going to use a good piece off that to fix the glued-on mount, rather than try to get the thing off (whacking with a hammer did nothing, absolutely nothing). What sealant should I use when putting the bolts back? Not that they are necessary for anything more than cosmetics, nothing will ever get that stupid antenna bracket off now...

5. Plastic cable gland to fiberglass hull. I plan to scrape out whatever sealant was used to halfway-seal the VHF antenna cable to the half-inch hole it came out of, and use a proper cable gland. What sealant would I use here?

Almost done with the electrical now, not much after that, so hopefully I get this boat into the water weekend after next.
 
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#2 ·
Patrick-

Might want to read this post. :)

Hello,

I have many things to seal. I wanted to both question, and verify, which sealant goes where.

1. Teak rub rail to fiberglass deck. This is polysulfide, such as Sikaflex or 3m 101, yes ?
Polysulfide...but make sure to wipe down the teak with acetone before applying the sealant.

2. Metal chock (is that how it is spelled) to wood - the wood is above the fiberglass, the metal chock sits on the wood so its above the rub rail, and is bolted through both wood & fiberglass. Is this polysulfide as well ?
If the wood is teak, yes, polysulfide is probably the best choice.

3. Plastic to fiberglass. The stern light will be attached to the stern. It needs a wee bit of adhesive strength, as the mounting hardware for the Aqua Series 32 stern light is fairly wimpy. 3m 4200 yes?
Since this is an LED fixture, the 4200 should be a good choice. :)

4. Metal bolt to nylon antenna mount that is 5200'd to the fiberglass. Well I have a big 8' VHF antenna off the stern of one of my hulls, and the antenna mount was broken during shipping. Undid the bolts, and went to remove the mount. Surprise! it's attached with 5200. Joy. I found an identical mount, and was going to use a good piece off that to fix the glued-on mount, rather than try to get the thing off (whacking with a hammer did nothing, absolutely nothing). What sealant should I use when putting the bolts back? Not that they are necessary for anything more than cosmetics, nothing will ever get that stupid antenna bracket off now...
Debond works to remove 5200... so you do have a choice... but if you're just going to replace the bolts... go with 4200.

5. Plastic cable gland to fiberglass hull. I plan to scrape out whatever sealant was used to halfway-seal the VHF antenna cable to the half-inch hole it came out of, and use a proper cable gland. What sealant would I use here?
I would go with either 4200 if you want the sealant to provide a bit of the strength for mounting the cable gland or butyl tape if you don't. However, IMHO, I would go with a through-deck PL-258 female-to-female connector instead of a cable gland and use that instead. It is a far easier and more secure way to do it IMHO.

 
#3 ·
I'll just use the cable gland since I've already bought it, and that VHF antenna is temporary (when I blow some money on a radar I'll get a proper mast-mounted antenna and run the new cables at the same time). It'll be better than the open hole it's running through now...

However, apparently I need to be mounting my stern light on a piece of teak, cut so that the light will be vertical to the waterline (my stern has a bit of an angle where I plan to put the light).

This all assumes I can even get an unobstructed 135 degree field of view from some spot on my stern, that's not necessarily a given. Need to check that out this weekend and make sure ...

In any case, I'd bolt the teak to the hull with 2 screws, and seal with polysulfide. Then two holes going thru teak & hull, for the wires and for the ridiculous expanding bushing that mounts the stern light. And I'd attach the stern light to the teak with that stupid bushing and the 4200 ?

How do I clean up excess polysulfide? Acetone?
 
#4 ·
Then two holes going thru teak & hull, for the wires and for the ridiculous expanding bushing that mounts the stern light. And I'd attach the stern light to the teak with that stupid bushing and the 4200 ?
The "ridiculous" and "stupid" bushing is working very well on my boat. I just bedded it in butyl tape, tightened the expander and it holds fine.
 
#6 ·
That would be awesome, SD, thanks!

Now it would presumably be butyl tape around the bolts to mount the PVC shim, and then 4200 the light to the PVC shim.

jarcher - Yes I believe in normal circumstances the stern light will hold just fine. I'd worry under a big breaking wave where the you have a slim line of plastic around the wires on the other hole, and that expanding bushing on the other side, that the light will get hammered right out. It also makes doing things like I'm doing now, installing on a shim, more complicated than it has to be.
 
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