Epoxy or not?

S

SeaRenity

Member
Mar 31, 2008
200
chesapeake bay / Back river
Boat Info
320 Sundancer 2005
Engines
350 Mag hor.
Need some advise! The past few seasons I have a small leak on the foredeck hatch. The leak is on the downslope section starboard side. I removed the hatch last weekend now that I she is under shrinkwrap and confirmed I had some leaking issues. My question is 5 or so of the perimeter hatch screws are somewhat stripped ( screws facing forward, where the leak is)-- should I allow to air/dry a few months then fill with epoxy? Is there a better way or better product? I have read that epoxy is brittle and when I try to install the screws the epoxy will crumble and not hold. Any suggestions? Thanks Rich
 
Assuming we are talking about a solid fiberglass part, then filling the holes with epoxy is fine. If these are through holes you may want to put tape on the back side to keep the epoxy from leaking. If you can't get access to the backside the you will have to mix some thickening agent into the resin (all of this stuff is available at marine stores like WM, or on line). I personally prefer the West Systems products (no relation to West Marine).
The first step is to drill out the existing holes with a bit just large enough to clean the threads and any cracked fiberglass/gelcoat. Then apply epoxy and let cure. Keep in mind epoxy cure times are temperature sensitive, pick a day when it is nice and warm under the shrink wrap. The trick is that when the epoxy has cured to drill the correct size pilot hole for the screw.

Henry
 
I would also oversize the holes and then apply the epoxy. This way when you drill down the middle of the epoxy the screw will not contact any wood/fiberglass/gelcoat which will give the screw more holding force. Also as an FYI as I assume you are not having to re-gelcoat anything, but just in case you do in the future, gelcoat will not adhere to epoxy very well at all. Epoxy adheres to polyester very well but not the reverse. Gelcoat is a polyester resin so gelcoat does not adhere to epoxy and may fail. This is just an FYI in case you wanted or needed to know.
 
Epoxy will never make a acceptable bond to polyester. Go ahead over size the holes. Then look up Plexus MA 300. This is an adhesive that makes a chemical bond to the polyester reinforced fiberglass. Fill the holes and cure. Then predrill and fasten back your screws. You can buy the plexus in 50 Ml tubes and need to purchase a hand gun to apply w/ mix wands. I do this for a living. Just my 2 cents.
 
My info is from Chemistry. When Sea Ray builds boats ( or buys sub-assemblies from vendors ) they do not use epoxy for bonding. Epoxy will stick but not form a fused bond. They use a fusor product like Plexus due to its abilty to chemicaly adhere the the joint. The Plexus bites into the polyester substrate thus chemicaly linking the two substrates. Boldly, Plexus even states no sanding or prep is nessesary prior to bonding. For optimal results we take a 36 grit disc to the surface then wipe w/ acetone prior to bonding. Mercury, GE, & Phillips have all tested the joints to failure and found the fiberglass failed and not the joint. ( I am a part owner in a composites company ) Mike
 
Thanks for all the responses -- Great information. I do believe that there is a wood core under the fiberglass that the 3/4" screws are holding into. The wood is wet, and as I mentioned I have the hatch out so it is trying to dry. Will the epoxy be ok under these circumstances? Again, I should be OK with the screws holding into the epoxy. Thanks Rich
 
Just replace the screws with ones that are one size larger. (If that is possible and the wood not rotted.)
 
Is that company Plexus?

If the wood is rotted then it needs to be removed as it will never hold any type of force, epoxy, plexus etc. Wood rot is just that, rot and needs to be taken care of before trying to place screws and mount things back in place.
 
SeaRenity said:
Thanks for all the responses -- Great information. I do believe that there is a wood core under the fiberglass that the 3/4" screws are holding into. The wood is wet, and as I mentioned I have the hatch out so it is trying to dry. Will the epoxy be ok under these circumstances? Again, I should be OK with the screws holding into the epoxy. Thanks Rich
Click to expand...


There is a product called CPES that is made for this type of wood rot. You can find it at rotdoctor.com. You will have to let the wet wood dry out for a while and the inject the CPES into the wood fiber. Should work out just fine. :smt101
 
ITW Plexus. There are several versions. The Plexus MA 300 has a faster set time then most. Mike
 
I tried the CPES and it does not work well at all. It might be ok for new wood that you want to encapsulate but if the wood has any moisture it just didn't seem to work well at all for me. Brushed on an edge, not bad. Injected into a rotten wood core, not worth it. Remove the wood and replace with a composite core would be much better and easier.
 
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