West System and Gel Coat?

I have a area about 5' by 8' that I have to reglass on my charter boat. Im in Chicago and boat hits the water by mid April.

Given my time frame for the glass work I'm really forced to use epoxy due to the low temps in the spring and no indoor heated place to do the work. The layup will be 3 layers 1708, 3/4" coosa, 3 more layers 1708 using West System. West Marine gives me a good deal on west system so it seems the cheapest option for the epoxy route

The final finish on the floor I would really like gelcoat again. Floor gets beat to crap 13hrs a day with 6 to 8 people. Looked into Durabak which is what I have in my cabin and really good luck so far but I like to clean with bleach and Durabak doesn't hold up to chemicals. Would like to avoid all the steps for awlgrip.

So question is how well does gelcoat stick to west system and if it does stick are there issues with cracking down the road? I know epoxy and gelcoat don't mix But west system has videos of gel coating over west system so maybe its different then the run of the mill epoxy resin?

I'm also looking at Raptor coatings but I would rather roll on then spray.

 

Was your boat built using epoxy or polyester?

Polyester on epoxy doesn't work. It stays tacky. That is one reason to stick to polyester to avoid any complications with future repairs.

Given the ambient temperature. Polyester is also a much better choice. Add a little more catalyst to speed things up. Your topcoat issue will be resolved as well.

Epoxy is a far superior resin and I prefer working with it. Especially new builds and repairs on wooden boats. And would never use it below 21 celcius. Our repair facility is kept at a low ambient temperature during winter and spring, mainly to avoid drying out wooden hulls.

Do you have a particular reason for going with epoxy?

 

Boat was built with polyester and polyester would be my first choice but given the time of year I have a window to do the work its not a option. Reason for Epoxy is in spring we may have a high of 50 and by mid April the boat has to get splashed and go to work. West System with fast hardener says its rated down to 40f and I can also heat up the bilge a little bit to keep it warm for a night.

 

If that's true I'd say go for it. However you will still have the topcoat issue.

I've worked polyester at those temps. 2-3% cat and it's tacky after a few hours. Hardened by the next morning. Not ideal, definitely undoable with the epoxy that I buy in bulk and have great experience with.

 

There is no problem with polyester gelcoat over epoxy, if it is allowed to cure. I put gelcoat over a large epoxy repair to test it. After 8 years, it is still holding.

 

How long does it usually take to cure?

I too have many times wanted to topcoat epoxy but have refrained due to the experience of tacky spots on polyester hulls. These have been sanded down to the gel but obviously had some past work done with epoxy.

 

The epoxy needs to be thoroughly cured before applying gel coat, and low temps don’t allow epoxy to cure well.

It’s not hard to heat an area that size, so polyester is an easy option. A halogen shop light will heat a large area, you need to make you keep it back off the surface a ways so you don’t cook it.

The same method will work with epoxy, but polyester is easier to use.

 

1708 has mat, which is not the best to use with epoxy. You will waste resin and get a heavy laminate. Biaxial stitched fabric is a better option.