What epoxy should I use for my mayfly 14?

[jasonikakis]

I'm currently building a Mayfly 14, and although I haven't yet reached the epoxy step, I'd like to start preparing for that as soon as possible to eliminate wasted time on research. So, what type (or specific product?) of epoxy is used, for internal filleting and external coatings?

[koederfischgriller]

Hi,

i´d ask Behnke ...

https://bootsservice-behnke.de


https://bootsservice-behnke.de/contents/de/d61.html


shipping costs should not be too crazy

[stromborg]

Here in the US West and System 3 are the big players, I don't know what you have in Greece. It really comes down to using what is locally available, I suggest visiting your local boating supply store and using what they have on the shelf.

[WI-Tom]

I'd say, lots of reputable choices--probably best to stick with one brand. I've used West Systems and System 3--both are fine.

Tom

[Todd Bradshaw]

Start by downloading this free book. It is the best text available on using epoxy resins for boat building, and though written by the WEST Epoxy folks, the vast majority of the information will apply to any boat building epoxy resins. Epoxy is great stuff if you know how to use it and knowledge is the key to using it well.

https://www.westsystem.com/wp-conten...k-061205-1.pdf

[Andrew2]

Start by downloading this free book. It is the best text available on using epoxy resins for boat building, and though written by the WEST Epoxy folks, the vast majority of the information will apply to any boat building epoxy resins. Epoxy is great stuff if you know how to use it and knowledge is the key to using it well.

https://www.westsystem.com/wp-conten...k-061205-1.pdf

What Todd says is especially good advice. All general purpose epoxys are stronger than the wood, so you are likely to find something local, or maybe online? Recently I have been using Amazon.de in English. Cheaper than the French version and quick delivery, might well be of use.
Personally I use Resoltech and another French resin company. Bit of googling in your future

[Edward Pearson]

The higher heat in a Greek summer will make your epoxy ‘set’ more quickly. The standard stuff is basically designed to go off at the temperature in northern temperate climates when standing comfortable in a T shirt on an overcast day. In Greece and being a new builder you might want to have the option of a ‘slow’ hardener and make sure your mixes are done in shallow trays rather than tall narrow plastic cups to avoid the ‘exotherm’ making it set double quick.

You are probably going to need more one sunday lunch time so I’d look at the local chandlery stock as well as mail order. MAS is best i’ve ever used followed by Sicomin (french). The Sicomin doesn’t crystslize. The MAS doesn’t blush and i think has/ retains flexibility more than most just from feeling it after its gone off in a tub. All seem to work, just understand how they work and get the mix ratio exactly correct and mix it. Stop for a second and go through again to make sure your not mistaken when figuring the volume of each/ or by weight. Write the mix ratios on the tubs. Leave out the left overs to check its rock hard the next day as verification you didn’t make a mix error.

[Andrew2]

Good stuff from Edward
I use a decent kitchen scale, good to a gram. Better than iffy volume pots.

[Todd Bradshaw]

If you are going to be doing some fillets You want to keep very close track of the mixture ratios of resin and whichever powder you are adding to thicken it. Test your formula on scrap wood all the way through to a solid cured state before you ever try it on the boat. You want to make sure that it doesn't eventually sag into a pool of goo before it hardens, which can be really frustrating and a mess to clean up later. Find your formula, test it to make sure it works, and stick tightly to that ratio for the fillets on the boat.

[Etdbob]

For fiberglass work on boats like this I use polyester resin, usually Bondo brand. I can get a gallon locally for under 40 bucks. I've used it for fillets some too, and it works fine (tape seamed boats were first made with poly fillets, not epoxy) but I usually don't bother. As far as I know, the only fillets on a Mayfly 14 are inside the boat where the bottom joins the side panels. Jim Michalak recommends a small bead of something there to prevent water getting in that joint and starting rot. This is especially important if the boat will be left outside upright, and will collect rainwater. I just use something that comes in a tube to seal that joint.

Does Jim specify tape-seams to seal the outside of the bulkheads too?

Uh, unless you are building her as a tape-seamed boat, not external chine logs as designed???

While on the subject of sticky stuff, I've come to prefer Titebond III glue above all others, although an earlier boat built with Titebond II hasn't come apart yet. I don't much care for the polyurethane glues.

Only time I used epoxy was to laminate a double layer bottom together, and I think it's worth spending the extra for it in that application.
The stuff I got was Raka brand from Duckworks, a three quart kit. It wasn't enough. If you are gonna glass the bottom with it, fill screw holes with thickened epoxy (which does work very well) and make yer butt joints with it, I'd recommend the 1-1/2 gallon kit, which will cost ya 113 bucks.
You'll probably have a bit leftover, but that's better than having to re-order it.

It is a pain to use, always having to mix it before you glue up something, and there is always waste - Or you didn't mix enough -
I'd leave all the screw heads that needed to be filled alone, and use up the leftover epoxy then, filling 'em up. If you have the time.

Be sure to use a slow hardener in this hot weather!

Bout the only other trick I can think to pass along is the use of waxed paper. Put it under the butts so you don't glue the sides to the floor...
Also, wax paper pressed and smoothed over a joint or fillet will save countless hours of sanding later on. It peels off later, leaving a nice, smooth surface! At least, it works very well with poly resin.

Eh, perhaps I should mention that I use ordinary bread flour to thicken epoxy with fine results! I've also used talcum powder to thicken poly and epoxy resin and that works too, but it really stinks of perfume when you sand it down. I use this kind of stuff to save coin, no need to send away for fancy extra fine wood flour or what-not to thicken resin.

https://duckworks.com/raka-resin-hardener-kits/

[Boatsbgood]

OK, this is a bit treacherous to engage...but. Epoxy. Wood boats, epoxy. Not gonna get into the weeds here, but polyester on wood boats is not the way to go. Cheap isn't the most important thing, if you are using your time and energy to build something.

[Todd Bradshaw]

Agreed. As one who originally started using polyester resin on wooden boats back in the days before boatbuilding epoxy became available, I see no reason to go back to it. The development of epoxy resins for wooden boat construction solved most of the problems common to polyester - poor sealing capability, shrinkage and delamination. There is not, and never has been, a formula of polyester resin specifically developed for sealing or gluing wood. This is why there are lots and lots of old powerboats out there with a big sheet of delaminated, water-damaged plywood stuck in their transoms. Spend the money. buy epoxy resin and don't make needless future problems for yourself and your boat.

[WI-Tom]

Jason, as a new member, you may not recognize the level of expertise some of these posters have, and share openly for everyone. Todd Bradshaw is one of these experts. If he suggests using epoxy, I'd believe him. (My own opinion is the same, also based on having used both polyester and epoxy).

Tom

[Andrew2]

As above, the Mirror dinghy, sold as a kit in the thousends (sail numbers over 80K) used polyester resin and tape. Worked surprising well and lasted. But it would have been better with epoxy, if it was available back then. OK it cast a lot more, but that is only a small % of the materials and effort when building a boat. Personally I like it as a glue, rather than tape and fillet style. But, that depends on the design. Yours is mostly ply to stringers/log chines? So you don't need that much.

[John Meachen]

Good stuff from Edward
I use a decent kitchen scale, good to a gram. Better than iffy volume pots.

I use a digital scale with 0.1 gram increments.I have been caught out by one that had endured a set of corroded batteries and one that didn't seem consistent from day to day.

[Todd Bradshaw]

I switched from polyester resin (Techniglass/US Polyesters 329-2 unwaxed laminating resin was the best we ever found for use on wood after a lot of experimentation and we applied it over a couple primer coats of Pratt & Lambert Vitroloid lacquer sealer) to WEST Epoxy around 1975. I have always used the WEST mini pumps to measure and have never had a batch fail to harden properly. If you take your time and use your head there is no reason to expect anything else. For big glassing jobs, I do always have an assistant to measure and mix a constant supply of small batches. That is their only job and it keeps me from making any mistakes because I would be rushing to get the next batch mixed and get back to work.

[Larks]

Scales are a useful and easy method of getting a good mix ratio but make sure that you look for the products specified “mix by weight” ration as opposed to the more general “mix by volume” ratio that will most likely be more visible in the instructions. They can be quite different.

If the product doesn’t show a “mix by weight” ratio it’s easy enough to work it out by weighing equal amounts of resin and hardener separately, they will often have different specific gravities or relative densities. For example I use International Epiglass HT9000 which specifies a 3:1 "mix by volume” ratio but doesn’t provide a “mix by weight” ratio. When I weighed the products the ratio turned out to be 3.65 : 1