Which Epoxy is "the best bang for the buck?"

[Fast Shafts]

Im doing a major structural repair on the bottom and side of a boat. Which epoxy is the best per dollar? West System seems to be the best, but is also the most expensive. Other epoxies such as Raka, System 3, MAS and Total Boat, all have great reviews and vary in price. I'll need approx 3 gallons. Any suggestions? Thanks!

[Turtleherder]

I have had great success with Raka non blush epoxy. I’m not doing big structural repairs just stringers, floors and transoms but boats I have done 30 years ago are still in great shape. Three gallons is around $200.

[MattGreen]

Im doing a major structural repair on the bottom and side of a boat. Which epoxy is the best per dollar? West System seems to be the best, but is also the most expensive. Other epoxies such as Raka, System 3, MAS and Total Boat, all have great reviews and vary in price. I'll need approx 3 gallons. Any suggestions? Thanks!

Is there a particular reason you're going with epoxy over vinylester for a major repair? I've used lots of both, and definitely prefer vinylester for this kind of thing, and the fiberglass guys I know echo this. Was the boat laid up in epoxy originally (possible but rare)?

WEST Systems is pretty common and works fine for lots of things but is old technology and ovepriced for what it is. If you have your hearts set on epoxy there are better choices as indicated by Turleherder.

Matt

[Fast Shafts]

Is there a particular reason you're going with epoxy over vinylester for a major repair? I've used lots of both, and definitely prefer vinylester for this kind of thing, and the fiberglass guys I know echo this. Was the boat laid up in epoxy originally (possible but rare)?

WEST Systems is pretty common and works fine for lots of things but is old technology and ovepriced for what it is. If you have your hearts set on epoxy there are better choices as indicated by Turleherder.

Matt

The boat I'm working on was made with Vinylester. I'm leaning towards Epoxy because it is stronger than Vinylester. I've used Vinyl in the past and had success with it. Another concern is the short shelf life of Vinyl-a few months. Being that it is structural, I'm thinking of using the strongest stuff-Epoxy....and leaning towards RAKA non-blush. Why do you prefer Vinyl? Thanks for your input!

[rgsauger]

I used System three epoxy for my build. Their silver tip wets out more easily than their general stuff but both worked for me. Would buy again.

[LakeFever]

I’ll second the vinylester. I love the stuff. It bonds great, has the best secondary bonding window, completely waterproof, can be gel coated, and disolves the binder in stitch matt where epoxy does not. My supplier was pretty adamant that material choices are different for epoxy he strongly advised against any stitch matt with epoxy and suggested roving was the way to go. Can’t remember all of it but there was enough hmmms for me to skip epoxy. Poly is crappy to work with imo, mainly for adhesion to old glass issues, poor secondary bonding window means too much grinding which also compromise the glass just laid.

that said, there is no denying all the strength benefits of epoxy as well as controlled kick timing. Cant really go wrong either way

[FUJIMO]

...vinyl. not epoxy. you want to stick with "like" materials with large repairs/use. epoxy on an epoxy boat, etc...

[LakeFever]

Thats a good point Fujimo, if repairs are made in one area with a much stronger resin like epoxy, its going to make the hull flex on wave impacts all out of synch. Might even make the seam where the factory poly and epoxy meet become a high stress area

[XstreamVking]

Agree with Fuji also. I only use epoxy on epoxy things. Just no advantage in mixing materials. The vinyl is plenty adequate in all the physicals.

[Gordon02]

I use the 3:1 Laminating epoxy from US Composits. I used 8 gallons on my last project and almost that many on the 7 projects before that. You can certainly use 1708 with epoxy since 1708 has the 17 ounce woven fiberglass because the 8 ounce mat is stitched to it. In fact, I've always heard and understood the use of stitching to hold the two fabrics together was so that epoxy could be used. While true, you cannot use regular mat (non-woven fiberglass mat) with epoxy as the binder used to hold the fiber strands together must be dissolved by the MEK used with polyester resin.

If you Google "Epoxy versus Polyester Strength", you'll read that Epoxy bonds can offer up to 2,000 lbs per square inch of adhesion strength. The best of Polyester Resins offer a maximum of 500 and less. The point I make here is that if you want to bond/hold/stick to something, then I would use epoxy. My exception to this is if I am making fiberglass panels or parts that I will later laminate to the hull, I will make those in one layup. If mat, 1708, or other fiberglass fabrics are rolled out and laminated as a solid piece or panel, then I make those using polyester resin. I will then cut/trim those to shape, grind and laminate using epoxy for the joints and bond areas.

You can do your own demonstrations to see what is best for the application - using the material (wood or fiberglass) of your choice, fashion a test laminate by first grinding both surfaces to a 35 or 40 grit bite, then laminate with the before mentioned resins. Once cured, pull them apart. My experiences show the epoxy bonds will hold while the material and everything attached to it will be destroyed. I've seen White Oak and marine plywood pulled apart internally before the bond breaks loose. I've restored old boats with keels, stringers, and flooring supports held in with Polyester and rarely have those been difficult to remove. The bad news about epoxy ? - you won't be pulling that seam or bonded member out/off without pulling the bottom out where bonded.

[XstreamVking]

It's nor really the materials used, it's the quality of the prep and application. Use what you are comfortable with.

[25ss]

Also if you keep your vinylester in the refrigerator it has a lot longer shelf life.