Bob Meyer's Foam & Glass Boat Construction
This is a Baidarka, a boat design from the Aleutian Islands. "Baidarka" is the Russian word for "little boat." The design was taken from a drawing found in the British Museum, London. The original frame is there too. It was built for a British explorer who spent two years with the Aleutians in the 1850's.
Baidarkas were skin-on-frame craft, and in capable hands, were very good at sea. They had to be, because the wind and weather around the Aleutians is some of the worst in the world. In building this boat I wanted to combine an ancient design with modern technology. I used insulating foam available from the hardware store for the basic structure. The secret is to use the inexpensive 1/2 inch thick foam available at any hardware store with West System(tm) resin and hardener, which does not harm foam (it's solvent-free). Fiberglass provides the strength.
The structure is glued together with ordinary white carpenter's glue. The fact that this glue is not waterproof is irrelevant once it is covered on both sides with fiberglass and resin to form a very light and strong waterproof sandwich. The photos show my method of working. The first photo shows a sketch of the boat outlining the basic idea. Shown also is a mechanical drawing detailing the lofted sections of the boat shape. I then built a scale model to confirm that my sketches were true. I then enlarged these sections to full sized templates and began cutting the full sized sections. The *"bifurcated bow" piece, the keel and gunwale, or top sections. It was then a matter of cutting out all sections with a snap-off blade. The plastic vapor barrier must be peeled off the sides of the foam.
When completed all the sections were covered with fiberglass and resin. The boat was built in three parts, the bow, the cockpit, and the stern, because of working space limitations and because it allowed bow and stern watertight bulkheads to be easily fabricated.
The boat is 15 feet 6 inches long and 21 inches wide. These dimensions are personalized and were derived using the Aleutian system of body measurement.
The three parts were covered with foam strips as needed. When the hull was put together it was then glassed both inside and outside to form a structure both light and strong. Note that the sections were designed so that the center forms could be "knocked out" during final construction. As you assemble it you can use a stretched wire above the table to assure yourself that the boat is straight.
The hull was then painted with latex which forms a smooth finish and provides the necessary UV protection. The deck is constructed and sealed with fiberglass and painted on the inside. The deck is fiberglassed on the outside and everything is trimmed and smoothed with a "random-orbital" sander. The glass weave is filled with several coats of grey automotive primer and then sanded again, being careful not to disturb the glass weave. Several of the following are early trial photos in primer coat. Next are photos of the boat in flat latex outdoor paint and the remainder of the photos show the boat in a variety of views.
This boat was constructed in 2005 and remains in use in 2007. It has suffered one puncture on a particularly nasty submerged pipe, but duct tape came to the rescue as a temporary repair, and the later fiberglass repair was quite easy. Minor outgassing by the foam does require occasional attention (add pinhole and then reseal).
* Note: The bifurcated bow is said to perhaps resemble a seal's mouth.
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Some Answers to Your Questions
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Q: What about the strength of a foam and glass boat?
A: The structure gets its strength from the shape. Think of a foam and glass sheet as a sheet of paper. It's not strong until you put a vee into it -- then it becomes stronger. Turn the vee into a U-shape and it is stronger still. Then make the section a square, and more strength is gained. Turn the section into a circle and it becomes a monocoque shape and the structure is the strongest -- perhaps 50 times as strong as a flat sheet, with no additional increase in weight.
Q: How is fiberglass laid up?
A: I cut templates to conform to the hull shape with enough glass material to overlap each strip by at least two (2) inches. This adds additional horizontal strength. On this project I was trying for an ultra-light boat. My Baidarka is 32 lbs plus 2 lbs of paint for two finished coats. It is very light -- too light for me in fact because the boat sits on top of the water, not in it. And like the Aleutians, I have to add ten (10) pounds of sand behind the seat for ballast, to make the boat more stable, by lowering the center of gravity.
My three (3) piece foam boat is 39 pounds, and weighs more than my much longer Baidarka because 1/4" plywood was used for the four (4) connecting bulkheads, a floorboard and a seat. Plywood is heavy! I also put two layers of fiberglass on the hull and deck.
Please note that foam is used to convey the shape of the structure. The earth circling "Voyager" aircraft was built of foam and glass with very few hard points. These points were made with carbon fiber, which is 4 to 5 times stronger than regular fiberglass and resin.
Q: Where can someone get additional info on using fiberglass and the West System epoxy?
A: A quarterly magazine is available free of charge called EPOXY WORKS. It is published by;
Gougeon Brothers
100 Patterson Ave.
P.O. Box 908
Bay City, MI 48707-0908
They also publish a book called; "The Gougeon Brothers on Boat Construction." Write to the same address. These publications are top notch in terms of information.
Q: What about dings and hits to the hull?
A: Both of my foam and glass boats have been smacked around, mostly by the elements. Scuffs and bruises can be filled with "Bondo," an auto repair epoxy material available at most auto supply stores. Note that any cut or scuff that gets down to the foam must first be painted with white carpenters glue and allowed to dry or the solvents in the "Bondo" will damage the foam. I put a three (3) inch diameter hole in my Baidarka once. I filled the hole with a foam plug the size of the hole and glued it in with white glue and covered that with a glass and resin patch. I sanded down the edges, added some auto filler and repainted the patch area -- which is now invisible.
Q: Is the foam necessary?
A: It is the easiest way to sculpt a kayak or any shape. True, it has little structural integrity, but strong enough to hold itself together during construction and it provides for a buoyant boat without the need for airbags or airtight bulkheads. With two layers of glass and resin you're not going to dent it with your fist. One glass layer makes the hull more fragile but you're not going to ding it with your fingers or hits from most rocks for that matter.
Q: Why use something as cheap as foam insulation to build a boat?
A: If the blue or pink polystyrene foam is too cheap for you, you are free to use polyurethane or PVC rigid foam at 50+ bucks a sheet. This foam is approved for building airplane structures and cuts beautifully with a hot wire (avoid the fumes). This foam is required by the designers of the "KR-1" and 2, the "VariEze" and the "Long-EZ" aircraft to name a few contemporary home-builts. But Kayaks don't fly, and don't need to take high "g" loadings which could pull them apart.
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From the "Old Codger," who has paddled the entire Mississippi River, the Yellowstone/Missouri Rivers, the Illinois River, the Minnesota rivers, and Lake Champlain and the Hudson River down to Poughkeepsie, New York.
Bob Meyer, St. Louis, MO
(E-mail to Bob can be sent with "BOB MEYER" in the subj line to galt_57@hotmail.com)