Mostly retired spend all my time working on or thinking about boats and outboard motors :)
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Epoxy and Glue

When it comes to Epoxy there seems to be no common ground amongst wooden boat builders.

They either love the stuff or hate it. While there are no doubt some building methods where epoxy in inappropriate, plywood construction is definitely not one of them. In fact, without Epoxy it isn't a viable and durable method.

So yes, I used epoxy and a lot of it.

So what's the best brand of epoxy to use? If you stick with any of the major brands the answer is - whichever you find the easiest to use.

You have your choice between West System, E.A.S.T. System, System 3, MAS, Industrial Formulators, RAKA, a bunch I can't even think of, plus dozens of privately branded to specific builders/suppliers, made by one of the above companies, and sold to a local client base.

All epoxies are a "two part" system with the first part being a Resin and the second a hardening agent.

Without getting too deeply into the subject (there are very very thick books on the subject), most of the resins are near identical, the hardening agents allow for either a slow or fast cure depending on your particular needs and the temperature at which the product is being used.

The two components must be mixed at specified proportions for the product to cure correctly. The most common are 5:1, 3:1, and 1:1.

In "general" the 5:1 will produce a "harder" less flexible finish than a 1:1.

I am using West System. The standard resin can be mixed with either fast or slow hardener (5:1 for bonding), or an extra slow or special coating hardener (3:1 for encapsulation/glass work). All structural bonds will be made with thickened epoxy (silica or microfiber additives) as per WEST's instructions.

I followed the recommendations of the mfg quite closely and copied their methods - after all, the "brothers G" did write the book on epoxy.

I chose West System for my epoxy because:

Initially I was going to use a product produced exclusively for a supplier called Clark Craft (Buffalo NY area). It would have suited all my needs, the price was great and I lived less than 2 hours drive from their shop but on the Canadian side of things.

Well that idea kinda got squashed. First off, crossing the border got alot more complicated and time consuming (even with a passport). Second, the Canadian dollar which had been running at par with US buck for a while, tanked again to 88 cents. And third, I moved to Eastern Ontario adding three hours to the trip - so my "economical" option kinda went down the drain (and it's really difficult to ship epoxy accross the border by most commerical means - somebody in customs got the idea that it's "hazmat").

Because of that I had settled on using EAST system simply because it was a little cheaper than the others (and just as durable etc) when I came accross a super deal for two of the big jugs (4.3 gals) of WEST system resin - so it won by default :)

For my cabinet work in the cabin, I picked up a quart kit of System 3's "T-88 Structural Adhesive" - it's a 1:1 epoxy that is said to be suitable for marine bonding without being thickened (which would save a step and some cost). So I figured some limited use on my current build would give me a sense of how well the product works and if I am satisifed with it, it may see some action as an adhesive for frames etc on my "next" build.

Why not use wood glue, super glue or any of the other products out there that can suspend an elephant from a steel beam dangling three stories above a busy street? Simple answer - they are not "marine" rated. Yes, someone can provide you all kinds of facts and figures showing how much stronger they are than epoxy but that proves very little.

How much stronger do you want? Would you pull your 16 foot fish/ski with a Mack truck? why not? The simple answer is, your 6 cylinder passenger car is more than adequate.

It's great that some of these new glues can support an elephant but that will be of little consolation when your frame beams start separating when you are a few miles from shore because water or constant "damp" caused the glue lines to separate or dissolve.

I have been doing cabinet work for a number of years and when the polyurethane glues hit the market I thought they were the greatest new invention (well at least new to the mass market).

You could glue up a cabinet frame with the stuff (sold under brand names such as Gorilla glue or ProBond) and you would literally have to shatter the wood to get them apart. Strong, oh yes - suitable for a marine environment - not yet. Until one of the mfgs puts their reputation on the line stating that their product is for marine use, I will limit that product to the cabinet work in the galley and use the tried and tested product for all structural components.
 
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