What Kind Of Epoxy

[scarlet]

The mast on my sailboat sits on, and is attached to, a stainless steel plate that is about 18" x 18" square. The reason it is there is that at one point in our boat's history, the coach roof started to sag. The previous own decided to put a large support bar under the coach roof, and then place this SS plate on top to shore things up. Overall, not a bad solution.

The SS plate sits directly on the fiberglass. I do not know how it is adhered to the fiberglass, all I know is that there is a slow water leak that I want to fix. I do know that at one time the previous own put some type of caulk all around the plate to prevent leaks. This did not hold up.

I want to remove all that caulk, and seal it a different way. I assume that applying a bead of sometype of epoxy would be appropriate, but there are so many to choose from, I don't know where to start.

Could someone recommend a good Epoxy for sealing between Stainless steal and Fiberglass?

[Privilege]

If you're removing the plate and re-bedding it, then epoxy may be the way to go as it is a tremendous glue. However, if you're just trying to seal it, I wouldn't go with epoxy as a filler as it is somewhat brittle and the flexing will likely crack it. Assuming that the area is subject to slight flexing forces, for gluing the plate down, use 3M's 5200. If you don't need the superior adhesive quality of the 5200 and you're just sealing the edges, use the 4200.

In summary...use 4200.

[chris95040]

Originally Posted by scarlet

The mast on my sailboat sits on, and is attached to, a stainless steel plate that is about 18" x 18" square. The reason it is there is that at one point in our boat's history, the coach roof started to sag. The previous own decided to put a large support bar under the coach roof, and then place this SS plate on top to shore things up. Overall, not a bad solution.

The SS plate sits directly on the fiberglass. I do not know how it is adhered to the fiberglass, all I know is that there is a slow water leak that I want to fix. I do know that at one time the previous own put some type of caulk all around the plate to prevent leaks. This did not hold up.

I want to remove all that caulk, and seal it a different way. I assume that applying a bead of sometype of epoxy would be appropriate, but there are so many to choose from, I don't know where to start.

Could someone recommend a good Epoxy for sealing between Stainless steal and Fiberglass?

I think you want something more flexible. What you are talking about doing is "bedding" the plate to the deck, and a "bedding compound" such as polysulfide would be appropriate.

For something permanent like this I'd probably even use an *adhesive* caulk like 4200 or 5200 after THOROUGHLY prepping both bonding surfaces by scuffing and cleaning - when using products like that you want to never have to revisit the bond ever again.

I'd root cause your leak. If the fasteners holding the plate to the deck are leaking, they could be rotting the wooden core material that is embedded in your deck fiberglass. You don't want that, and you want to make sure your work here addresses it.

[Almost-There]

I'd first find the leak and if there's any fasteners in the deck that's probably the culprit.

Make sure the core is good and dry, remove and fill with epoxy making a solid plug to drill through. This will prevent future issues with water intrusion and compression. I've found compression leads to leaks among other problems.

Then seal and bed the plate with plenty of 5200 and be done with it.

[Cheechako]

The good way to fix it is to remove it and clean up then seal with caulk. 5200 will be nearly permanent. Other caulks should work too. Is it screwed on? If so the screw holes are likely the problem and you may have water in the cabin top core... as mentioned.
That's an awful big plate for a 22 ft boat or even a 40 ft boat! If it has been reinforced underneath then it doesnt have to be near that big.

[ArmyDaveNY]

If you desire an epoxy but also need flexibility you could use G-Flex epoxy. It is great stuff and unlike normal epoxy, it has good flexibility. West Systems makes it and I've used it. It is quite good stuff. It is also good for bonding dissimilar materials. I am sure other manufacturers make similar products. Good luck with your repairs.


There are also some good videos on this stuff.



WEST SYSTEM | Specialty Epoxies - G/flex

[roverhi]

Find out where the water is coming from. A deck leak will soon lead to core rot which may already be the case for your boat. Trying to seal where the water is coming out is sticking your head in the sand.

Epoxying fastener holes.

If you want to do a permanent fix for any fastener through a cored deck do this.

1. Drill your holes through the outer laminate only. You don't want to go through the interior laminate if you can help it. If you drill through the inner laminate you'll have to deal with the gap between the liner and deck that will allow resin to run out the bottom. If you do drill through and can get at the backside, use duct tape or other seriously sticky tape to seal the hole. Don't even think about using masking tape and you know how I learned that. If there is a liner, best thing is use a suitable hole saw and cut a large enough hole that you can use tape to seal the inner laminate closed. Fill the hole you’ve cut in the liner with plugs available from McMaster Carr https://www.mcmaster.com/#snap-in-plugs/=1a8svq4

2. Get a Dremel tool with a Dremel 199 bit.
https://www.amazon.com/Dremel-199-Hi...ds=dremel+1993.
Cut the Dremel bit into the hole at as close to a 90 degree angle as you can. This makes for a very minimal enlargement of the drilled puka to maintain deck integrity and hopefully the fitting will cover any damage to the gelcoat. Once the bit is cut in, raise the tool to vertical and rout out the core. I’ve tried the bent nail, sharpened Allen wrench, etc, without a lot of success. The Dremel 199 bit works way better, less damage to the gel coat and easy to do for fastener pukas. If you’ve other that just s fastener puka, the other tools might work better though not for me.

3. Once that's done, vacuum out the hole. Dill a syringe with epoxy resin and fill the hole. This soaks the resin into all the void to be sure the core is completely sealed. Have discovered that West Systems has a very slow catalyst (#209) that will allow you to fill a bunch of pukas without the resin kicking in temps over 70 degrees. Use the regular slow hardener (#206) if temp is much below 80 degrees or the epoxy will take forever to go off. If you need the fast catalyst (#205) it’s too cold to be working and wait for spring.
https://www.westsystem.com/the-105-s...ins-hardeners/

4. Suck out as much of the resin as you can and mix with a structural filler like West 404. Reinject the thickened epoxy into the puka.

5. After the resin has set redrill the hole. The thickened epoxy makes an incompressible base for the fasteners. Personally believe that most of the leaks into deck core is because the installer puts too much torque on the fastener and compresses the core.

6. Finish by chamfering the edge of the hole with a counter sink bit. The chamfer allows for a thick donut of whatever sealant you use around the fastener shaft. That goes a long way to insuring that the fastener won’t leak again. Whether you decided to do the epoxy thing or not, chamfering the edge of the fastener puka is a must for any hope of a leak free install of any fastener.

[ramblinrod]

Originally Posted by scarlet

The mast on my sailboat sits on, and is attached to, a stainless steel plate that is about 18" x 18" square. The reason it is there is that at one point in our boat's history, the coach roof started to sag. The previous own decided to put a large support bar under the coach roof, and then place this SS plate on top to shore things up. Overall, not a bad solution.

The SS plate sits directly on the fiberglass. I do not know how it is adhered to the fiberglass, all I know is that there is a slow water leak that I want to fix. I do know that at one time the previous own put some type of caulk all around the plate to prevent leaks. This did not hold up.

I want to remove all that caulk, and seal it a different way. I assume that applying a bead of sometype of epoxy would be appropriate, but there are so many to choose from, I don't know where to start.

Could someone recommend a good Epoxy for sealing between Stainless steal and Fiberglass?

Yeah, coach roofs on boats with deck stepped mast don’t sag unless something is seriously wrong. Most deck stepped masts have a metal compression post between the keel and coach roof. On the top of the coach roof is the mast step, typically an aluminum casting. The load of the spar weight and rigging tension is transmitted through the mast, to the mast step, to the coachroof, to the compression post (which often has a plate on top), to the keel.

For the coach roof to sag, means something structural has weakened. If the coach roof had a leak near the mast step (mounting bolts or mast wire penetration) for a long time, there is a good chance the deck core is rotted and been squished. Puttting s large plate over this is not a proper fix.

The correct fix is to remove the mast step, repair or replace rotted core, fix the leaks, and remount the original mast step.

Sometimes on small boats there may be wood compression posts, or metal with hardwood wedges under, that may rot and cause sag, but if this was true in this case then a larger mast step plate was really really the wrong solution.

Boats are normally designed by fart smuckers so where ever possible, the repair solution should be to make it as close to original as possible, to avoid introducing another (perhaps even bigger) problem.