Rub rail to hull sealant

[Night Watch]

Hi,
I have a wood rub rail and fiberglass hull. The sealant between is gone in some places. TGOD ( The Guy on Dock) says to use SIKAFLEX 295 UV ( going with black )
Any hints ? I will be taping both sides then using standard gun with nozzle cut on an angle. May smooth it after it’s on with popsicle stick rounded end as that worked on something else to give smooth finish, but not sure if this will be too sticky. ( I moved the end of tape to call attention to the gap but will smooth it out before application.
Thank you!!

 

[Giggitoni]

Sikaflex is a good choice. Have you considered removing the rub rail and re-bedding it with Sikaflex?

 

[Andiamo2018]

This is just for looks? No leaks? A good tape job and whatever UV goo you like will work.

Chances are though that the adhesive near the mountings is going too. Removing and rebedding or at least pulling the fastenings might be needed.

My choice for anything like rub rails, deck hardware etc is 5200. The black version is runny though (no one has told me why it is so much more runny than the white) so be really careful if you pick black.

 

[Comodave]

I used to use the 3M caulks but have moved to Sika products now. They seem to hold up better to me. Jamestown Distributers has technical info on the Sika products. I have been using 291 for general caulking. the 295UV is designed for sticking to plastic windows. I used 295UV to caulk my Lexan venturi windscreen to the fiberglass and it has held up very well so far. They also recommend using a primer in some applications. I recaulked the toe rail, teak, to the fiberglass deck with 291 and used the primer. It has also held up very well. I would not use 5200 in this application since it will be extremely difficult to remove if you need to redo the caulking.

 

[bayview]

Scrape out the joint and blow it out with air or water then let it dry well.

 

[Andiamo2018]

I used to use the 3M caulks but have moved to Sika products now. They seem to hold up better to me. Jamestown Distributers has technical info on the Sika products. I have been using 291 for general caulking. the 295UV is designed for sticking to plastic windows. I used 295UV to caulk my Lexan venturi windscreen to the fiberglass and it has held up very well so far. They also recommend using a primer in some applications. I recaulked the toe rail, teak, to the fiberglass deck with 291 and used the primer. It has also held up very well. I would not use 5200 in this application since it will be extremely difficult to remove if you need to redo the caulking.

I like Sika products too. But if I was rebedding a rub rail that I expected to stay in place indefinitely, years, then I'd use the 5200. Clean out the old bedding, loosely mount the rail and tape everything off. Then remove it and wipe everything with acetone and reinstall it. Without tightening it down so much that it squeezes out all the 52. Wipe off excess and then remove the tape.

BTW, I like to do a little countersink in the hull (or whatever / wherever the fasteners go) so whatever goo I use will form a little gasket for extra protection from water intrusion.

I am gluing down my teak deck slats with 291 though because I'm only doing it in a few spots. Plus Sika is cheaper than 3m

 

[DDW]

5200 will yellow and eventually degrade in the sun. 4000UV is a better product for this in the 3M line.

If you have a gap between hull and rail, pushing some sealant in will be a temporary fix. The more permanent fix is to remove and rebed the rail, but admittedly a lot more work.

 

[Night Watch]

Rub Rail

I have a place where the rail split under the bowsprit but other than that it is attached. It has separated from the hull only a small amount and no leaks so saving the rebedd job for the future.
My main concern is getting it down in the small gap, hopefully it is runny enough to go in but won't know til I open the tube.
Thanks all!

 

[Comodave]

The caulk probably will not run down into the gap unless you use the pressure from the caulk gun. Unless you use the 5200. It will run like crazy if you are not careful. Personally I would not use 5200 for this in case you have to ever get it off, but if you do watch it and maybe tape below the rub rail in case it runs.

 

[Night Watch]

Good idea

Thanks - I’ll be aware of it dripping through in the two spots I know about

 

[Bacchus]

5200 will yellow and eventually degrade in the sun. 4000UV is a better product for this in the 3M line.

If you have a gap between hull and rail, pushing some sealant in will be a temporary fix. The more permanent fix is to remove and rebed the rail, but admittedly a lot more work.

If you have a gap between the deck & hull it may be a failure of the fasteners which in most cases are different than the rub rail fasteners... depending on the joint design. On my Mainship they used screws to join the hull & deck flanges and some pull through and lose effectiveness allowing a gap. If you loosen some either side of the gap, fill and rejoin it will be better than just trying to squirt in sealant. I had to replace a few screws w bolt & nuts and would have been a more secure method to start. Big job to replace all. Any bump on the rub rail can cause flex and open the joint / leak again.

When I rebedded mine I also drilled some deep holes in bottom of rub rail to allow water to easily drain vs trying to find a gap / leak path inside.
More info & pics on Bacchus website - Hull Deck Joint Repair
https://dkloeber.wixsite.com/bacchus/project-pg-4

 

[Barabus]

4000uv

 

[kapnd]

Be sure to get both surfaces really clean before caulking, it won’t stay stuck over wax and dirt that love to accumulate in such crevices.