Outfitting the tandem kayak, Part 1: The Materials

I. Resin

The resin I use is pictured at left.  Resin is simply a plastic in liquid form.  When the two parts are combined, it hardens into a solid in an hour or so, and cures to its full strength over the next one to three days.  The pumps on the two cans (sold separately) are calibrated to dispense the resin and hardener in the correct ratio.  I mix the two parts in a plastic party cup like the red one in the photo.

The resin pictured is epoxy resin, generally the best thing for building boats and other marine-related objects.  There are other types of resin, such as polyester and vinylester, that I understand are fine for building accessories like the bulkheads and hatches and stuff that I'll be building in this project, and they generally cost less than epoxy resin.  But at this time I have no experience with them, and I'm sticking to what I know.  One day I'll get around to trying those other resins out.

Whatever type of resin you use, take this advice: spend a little extra and get the good stuff.  If you use the stuff they sell down at the auto parts store, you WILL be disappointed.  The Gougeon Brothers West System brand pictured is about as good as you can get for marine applications.  I've also used the System Three brand, on a project I did several years ago, and it seemed fine as well.

So, where do you go to get good resin?  I buy my resin (and numerous other things, as I'll explain later) from a mail-order supplier called Sweet Composites.  John Sweet, one of the best whitewater racers in the U.S. back in the 1960s and 70s, founded Sweet Composites to provide boatbuilding materials for his fellow paddlers (back then, in the days before Perception Kayaks and other manufacturers, the best way to get a good boat was to make your own).  When Sweet retired a few years ago, he sold the company to Jennifer Hearn and her husband Davey, a world champion and three-time Olympian in whitewater slalom, and they now run it out of their home in Bethesda, Maryland.

There are other places to get good-quality resin; the West Marine chain of stores is probably the best-known.  I have not compared prices to see where I can get the best deal; personally, I prefer mom-and-pop companies over large national chains even if I have to pay a few more dollars.  Since Sweet Composites is operated by paddlers, for paddlers, they're a cinch to get my business.

Sometimes it is desirable to add a thickener to your resin to increase its viscosity.  Unthickened resin has the consistency of thin maple syrup; you can thicken it into a putty thicker than peanut butter.  Happily for me, one of the most common thickeners is a by-product of my woodworking business: wood dust.  I keep a jar (pictured at right) full of the dust from my belt sander and random orbital sander and keep it handy for resin-thickening purposes.  The downside of wood dust is that it turns the resin a chocolate-brown color, which could be a cosmetic problem.  I only use it on the inside of a boat, or in non-visible woodworking applications.  Sweet Composites sells a variety of thickeners for a variety of situations.




II. Cloth

Race boats and other high-performance canoes and kayaks are made of cloth.  The cloth is saturated with resin and laid into a boat-shaped mold, and after the resin cures, it all comes out of the mold, and it's a boat!  That's the very basic explanation, anyway.

There are different kinds of cloth, each having desirable properties that the others lack.  Therefore, most boats contain layers of two or more of them (that's why such boats are often called "composite" boats).  The photo at left shows the two types of cloth I use the most.  The white cloth is basic fiberglass, sometimes called e-glass or s-glass depending on its weave and strength.  The gold cloth is Kevlar, developed and trademarked by the DuPont company.

What's pictured here are assorted scraps of cloth that I keep in Rubbermaid containers to protect them from dust and moisture.  In the little white sleeve with "KEVLAR" written across the top is a pair of scissors that I keep with the Kevlar and use ONLY for cutting Kevlar (Kevlar is difficult to cut with anything other than very sharp scissors, and using a pair of scissors to cut fiberglass quickly ruins it for cutting Kevlar).

When I buy cloth, I sometimes buy part or all of a large roll like those pictured at right.  Sweet Composites sells fabrics in rolls or by the yard from said rolls.  If I don't need such a large quantity--if I need just enough to patch a boat, for instance--I can buy small bolts of it here in Memphis at Outdoors, Inc., our local outdoor sports retailer that I'm happy to support because it's owned by Memphians, one of whom is my good friend and training partner Joe Royer.  Fiberglass of various qualities and grades can also be bought in hardware stores and auto parts stores.  One disadvantage to buying cloth in some way other than from a roll is that it will typically be folded up into a plastic package, and as a result will have creases in it.

(By the way, the black fabric on the left in this photo is graphite (carbon) fiber, which I use only very occasionally.  Martha's boat has a carbon-fiber deck, and if it gets cracked I'll patch it with a piece of carbon fiber along with some fiberglass.  I also use the carbon fiber if I have to repair one of my carbon-fiber paddles.  In any case, this roll should last me a good long while, as long as I keep it carefully stored.)

These cloths also come in tape form, pictured at left.  The most common use is for the seams where a boat's hull meets its deck.

The Sweet Composites website has more information on all the different kinds of cloth and the pros and cons of each.  Go there if you want more information than I'm providing here.






Whew... I feel like I'm writing a book here.  Hopefully future posts on this project won't be so long once I get this background information out of the way.