Build Your Own Kevlar Canoe

 source: http://bwca.cc/tripplanning/equipment/canoes/kevlarcanoebuilding.htm

The Nitty Gritty on Building Your Own Kevlar Canoe by Ed StilesYou can build a Kevlar canoe for half the price of a commercial one. And a backyard boat-building project can be a lot of fun. Still, you wonder, ”Is working with Kevlar difficult, and what kind of mess does it make?” You can get a good idea of what’s involved by reading James Moran’s book, Building Your Kevlar Canoe: A Foolproof Method and Three Foolproof Designs. But to get the real nitty gritty, you need to talk with someone who bought the book, built a mold and laid up the Kevlar. I got a chance to do that recently when a friend at work mentioned the fishing trip she and her husband took in their homemade canoe. It wasn’t long before I was standing in Bob Bowers’ workshop inspecting the 18 1/2-foot-long ”Family Canoe” he built from plans in Moran’s book. The canoe weighs 60 pounds, cost $1,000 and took about four months to build. ”It was messy,” Bowers admits. ”You have white dust everywhere when you’re sanding off the mold, and you need a good respirator. You also have to wear latex gloves when working with epoxy. When you’re in the middle of building, it’s a great big, messy project.” Start Small! If you don’t have experience working with fiberglass, Bowers recommends building a couple of small, easy-to-handle projects before tackling a canoe. ”You could build some small bowls, for instance,” he says. ”You should make one using too much epoxy, one that’s just right, and one that does not have enough. That way, when you make the canoe, you know how much epoxy to use.” Or you could gain experience by building the fiberglass-covered grub box in Gil Gilpatrick’s The Canoe Guide’s Handbook: How to Plan and Guide a Trip for Two to Twelve People. Gilpatrick, notes that these plywood-and-fiberglass boxes are animal-resistant and can double as a camp chair or table. Easier Than It Looks! Working with fiberglass and Kevlar is not as difficult as it looks, Bowers adds. But getting a perfect, factory-style finish is not easy. ”To go from a pretty good outside finish to a perfect one would require half again as much time as I spent on the canoe, and the performance benefits would be negligible,” he says. Besides, the canoe’s first trip was down Arizona’s rock-choked Gila River from Clifton to Safford by way of the Gila Box. ”We ran over some monster rocks and high centered a couple of times, and a perfect finish would have been ruined, anyway.” Moran explains the building process in detail. But Bowers has a few tips to make things easier, based on his experience. ”Of course,” he adds. ”Once you’ve made one, building a second canoe would be a lot easier.” The Nitty Gritty Building the canoe involves: Drawing the plans and making a set of plywood forms (called stations). The stations are fastened to a central spine, and each station is a cross-section of the canoe at that point along its length. The final assembly, with the stations spaced along the spine, resembles a dinosaur backbone. Making the mold. This involves linking the stations (which will end up inside the mold) with foam strips. These are like the strips of wood that form the hull of a wood-strip canoe. After the strips are in place the gaps between them are filled with drywall compound. Finally, this foam-strip hull is sanded smooth. (At this point, you have a male mold on which the Kevlar and fiberglass are laid up.) Laying up the Kevlar and fiberglass hull. First, the Kevlar cloth and the fiberglass cloth are cut to size. (The canoe is made from an inner Kevlar shell, covered by an outer fiberglass shell.) Then the cloth is impregnated with epoxy to give it rigidity. Removing the hull from the mold and finishing the bow and stern. Kevlar and fiberglass cloth are epoxied to the bow and stern to finish the hull. (The ends of the canoe have to be left open in step 3 so the hull can be pried off the mold.) After the ends are finished, the hull can be painted. Adding the gunwales and ribs, which reinforce the bottom of the canoe. The top edge of the hull is sandwiched between two gunwale pieces. The excess hull material that sticks up above the gunwale is cut off. Adding the flotation compartments, and building and installing the seats, yoke and thwarts. Tips and Tricks Here are Bowers’ tips for making some of these steps easier. The numbers on his suggestions match the numbers of the steps above. Plotting the paper plans from dimensions in the book ”took forever,” Bowers says. So allow plenty of time. The stations are cut from these plans. Bowers used foam insulation that had aluminum on one side. The aluminum had to be removed before he could cut the foam into 1 5/8th-inch-wide strips. These strips are fastened to the stations and form the mold. ”The aluminum was a real pain to remove,” he says. ”You should find foam that does not have the aluminum.” He notes that Styrofoam will not work because epoxy melts it. Aviation foam also doesn’t work because it’s expensive. It also gives off poisonous gas if you cut it with a hot wire. ”Don’t be a perfectionist with the first coat of drywall compound,” he adds. ”You’re making a mold that goes on the inside of the canoe, so it doesn’t have to be perfect.” And don’t be stingy with drywall paste. Throw it on and spread it out. ”Buy it premixed,” he adds. ”It’s cheap and easy to use that way.” All the pieces of Kevlar cloth need to be cut before the canoe is laid up. ”You need to know which piece goes where, so its a good idea to mark them so you’re sure which end goes to the front and which end goes up,” he says. ”In the heat of battle, you don’t have a lot of time to figure out how things go together.” Standard household scissors won’t cut Kevlar. You can buy expensive scissors made for cutting the cloth, but Bowers says you don’t need them. ”I found hardware scissors worked well. I had one set lying around that didn’t work and another set that did, so you have to experiment.” The ones that worked were Wiss M-300 scissors. ”When we put on the Kevlar, there were five of us,” Bowers notes. ”One guy spent all his time mixing epoxy.” Even if you have the help of a good-sized crew, buy the calibrated pumps that measure out the proper amounts of epoxy resin and hardener. There’s not a lot of time for tedious measuring and weighing. The epoxy has to be well mixed, and tongue depressors can be used to scrape down the sides of the mixing bowl. Epoxy is applied to the Kevlar and fiberglass with paint rollers. ”You can’t let the epoxy get more than a quarter inch thick,” Bowers adds. ”It releases so much heat as it’s curing that it can start smoking through spontaneous combustion. Sometimes the paint rollers would start smoking. At that point, we had to get a new roller.” Air temperature also influences how fast the epoxy cures. ”If the manufacturer says it should be used between 65 and 85 degrees, use it in that range,” he says. ”At 110 degrees, even slow-curing epoxy cures too fast and I think at 32 degrees it would be like molasses.” Fast-drying epoxy can be handy for tacking things down and for touch-up work on small areas like the bow and stern. But Bowers estimates that he used slow-curing epoxy for at least 90 percent of the work. ”I used a shop blow gun with a rubber tip to get the canoe to release from the mold,” Bowers adds. ”I would break the edges and stick in the nozzle tip and the canoe lifted off pretty easily.” ”Finishing the ends took a long time, and the canoe ended up being longer than the plans called for,” Bowers says. ”I made the ends a little longer to give them more taper, and the canoe really glides through the water and tracks well.” Kevlar is sun-sensitive, and Bowers painted his canoe with a clear UV blocker to protect it. The Kevlar is difficult to trim down neatly to the gunwales because it tends to fray. Bowers found that cutting it with a router didn’t work. Instead, he used a sharp knife to trim the Kevlar above the gunwales. ”But it’s brutal on knives,” he says. ”I would make a few cuts and then I would have to put the knife in an electric knife sharpener.” Bowers also recommends using stainless steel screws to fasten the gunwales to the canoe. If the gunwales or canoe need repairs later on, the stainless screws are easier to remove than steel or brass screws that may have corroded. Since Bowers uses his canoe primarily for fishing and doesn’t do much portaging, shaving off the last ounce wasn’t a big priority. So he constructed larger, heavier floatation compartments than the plans called for. His compartments have flat tops and give him a handy surface for holding fishing gear and drinks. Alternative Solutions ”I built the canoe to save money, and a guy has to have a project,” Bowers says. But, he adds, there are other alternatives. ”You could buy a damaged outfitter canoe and patch it,” he says. ”This isn’t rocket science. Kevlar canoes are easy to fix. You sand off the finish and patch it.” Moran’s book includes instructions for doing this. Buying a commercially made Royalex canoe is another alternative if you don’t mind carrying a few extra pounds on the portages. Some new Royalex models cost about the same as the materials for a homemade Kevlar canoe, and they’re ready to paddle out of the box. Used Royalex canoes are even cheaper. Of course, some of us simply enjoy paddling a canoe we’ve built ourselves. Books and videos are available to help us build Kevlar, wood-strip or wood-and-canvas canoes. And some specialty canoe manufacturers offer classes in wood-strip and wood-and-canvas construction techniques. So if you’re yearning to build your own canoe this winter and spring, here are a few places to get started: Resources James Moran’s book Building Your Kevlar Canoe appears to be the only one available about building a canoe from Kevlar. The Wooden Boat School offers a wide range of boat building classes, including courses in wood-strip and wood-and-canvas canoe building. The Northwoods Canoe Co. offers plans, kits, materials, classes, books and videos. Bear Mountain Boat Shop offers plans, videos, books, courses and even a 1/12th size scale model kit for apartment dwellers or the less ambitious who would like to build a pint-sized wood-strip canoe. Canoe Passage Outfitters offers classes in wood-and-canvas canoe building. Amazon.com lists its picks for the best 99 books on boat building. The list includes several books on building canoes. Happy Paddling!
–article courtesy of BoundaryWatersMagazine.com