Skin-On-Frame Outrigger Sailing Canoe. Chapter 1: Deck, Keel and Cockpits

This is a 16 foot long outrigger sailing canoe. The shape is inspired by Marshallese sailing canoes. The internal structure of the hull is inspired by Inuit Kayaks and Umiaks.

This chapter is followed by:
Chapter 2: Make Ribs
Chapter 3: Lash the frame
Chapter 4: Carve Outrigger and Break Tools
Chapter 5: Hull Frame Finishing
Chapter 6: Morton's Oar
Chapter 7: Sew a Skin over the Hull Skeleton and Seal it
Chapter 8: Keel and Rub Strips
Chapter 9: Dipaakak
Chapter 10: Independent Suspension
Chapter X: Maiden Voyage

The design goals:
Light enough for one person to lift without getting hurt. That means 70lbs for men and 100lbs for women (they don't get hernias as easily). If it goes overweight Star will have to lift it.
Big enough to carry two people plus a few days of food and water.
Seaworthy enough to launch and land in minor surf.
Easy to paddle and possible to sail.
Easy to carry on top of a small car.
Quick and easy to carry from the car to the water, and possibly to portage.
Quick and easy to set up and launch.

Seen here with temporary jigs setting the shape of the keel.

Thanks to Star for much collaboration.
Thanks to Roland Chen for much advice about local conditions.
Thanks to Don Montague and Stephanie Simpson for hospitality and encouragement!

Please support the WAM canoe project as they preserve and foster canoe knowledge in the Marshall Islands.

We looked around for materials. Our host Don had some nice "luff cloth" sailcloth from his days as a sailmaker. We decided to make a skin-on-frame canoe. We kept our eyes open and grabbed various scrap lumber and materials when we saw them.

We didn't have any plywood thin enough for the deck, so we broke down and bought a sheet of 1/4" Luan plywood. We also got some "borated" rot-resistant boards to saw up for stringers and other parts. The deck would be 16" wide, so we sawed the 48" wide plywood into thirds lengthwise (48" / 3 = 16" ) with a Japanese pullsaw for ease of transportation, and to make some progress right away. We drank some coconuts while doing that and tying the lumber on the truck with trucker's hitches.

We tied strips of red bag to the boards hanging off the back to make it totally legal and safe.

We used a sabersaw to cut the ends of the decks pointy. Blunt and pointy anyway. Two such pieces butted up would make our canoe 16 feet long, which is perfect. I drew lines around a tin can to make the ends a 2" radius curve. I laid a flexible ruler on its side and bent it into a graceful curve to draw the taper from the straight sides to the rounded tip. I cut that out with a saber saw and shaved it down with my little wooden plane. Then I flipped it over to trace onto the other piece. Then I used that as a pattern to finish the first one. That's how I got them symmetrical. The ends look like gothic arches.

The remaining third of the sheet of plywood was cut up into more gothic arches to laminate onto the tips to make them strong. That part of a boat is called the "breasthook".

Describing the end of the deck and the breasthook:
What curve is the taper of the deck end (top view)? Nearly a "segment of circle" arc. The curve merges with the edge of the deck 2 feet from the tip. The curve is tangent to the edge of the "blunt tip circle".
The breasthook pieces are 3 feet long. The cutaway starts 1.5 feet from the tip. At the 2ft point the "leg" of the piece is 4" wide. At the 2.5ft point the leg is 2.5" wide.

I couldn't pack a tablesaw in my luggage, but I do have a circlesaw. I bolt it to the underside of a board and then do a plunge cut through the board. Now I have a tablesaw. For a fence I clamp a board to the table with C clamps or spring clamps.

KleinJahr says: "Nice build. The circ saw to table bit is an old construction gimmick. I would suggest getting a switched outlet ext. cord for it. That way you don't have to reach under the table to switch off the saw. Also, be sure to secure the table to the sawhorses. A bit embarassing to push the table, with a running saw, onto the ground."

Good point. Be safe. I later found a beefy plywood box to use for this. I turned the saw on and off by unplugging it from an extension cord, which isn't very good safety or convenience. A switch would be better. Don't ever use a foot switch for a power tool. That can make it into a trap with a foot trigger.

The best boards we could find were 1" x 6" x 16' borated SPF.
They had some knots in them, but we dug through the boards til we found some we could saw long, clear, straight grained pieces from.
Borated means impregnated with poison so bugs don't eat it so quick. It's not as bad for humans as the old arsenic-based pressure-treated stuff.
1" is "milled dimension" which is kind of like CRT measuring. Actually the board is only 3/4" thick.
SPF is lumber jargon for "Spruce, Pine, or Fir".
Use the swanky improvised tablesaw to rip one of the long boards down. Make the gunwales (upper edges of the hull) and stringers (lengthwise strips that will support the skin).
The gunwales are 3/4" x 2" x 148".
The stringers are 3/8" x 3/4" x 16' which is longer than we really need, but we got lucky with boards.
We'll cut them down later when we fit the skin on.

It's time to glue the decks on the gunwales.
Put on your gloves and safety glasses. Two squirts each of resin and hardener.
Mix it up. Add an equal quantity of white flour to thicken it up and mix again.
I use an electric drill with a bent wire as a mixer. Mixing by hand is just as good.

These metering pumps are pretty good. It helps that it's 75F out. When it's colder you have to wait a long time for the pump to spring back, and it often gulps air, which screws up the dose.

I gathered a bunch of pandanus keys to use as paintbrushes for the glue. Otherwise I'd have to wreck a store-bough brush every time I made a joint.

Lay the deck on the gunwales and see how it looks. The deck is still in two pieces. We'll glue on one half completely, then do the other one.

Mark how far the first deck extends over the sticks.
Paint your glue on the deck and the mating surface of the gunwale stick.
I don't have enough clamps, so I'll hold them in place with temporary nails.
After nailing the deck on, check to see if it's tight by squishing the deck onto the gunwale. If glue squeezes out or if there's a gap, add whatever clamps you have.
Repeat with the second half of the deck. Epoxy and butt the two halves up squarely. Try to make them straight. Try to make the edges straight.
Put the whole thing in the sun to make the epoxy cure quickly.
When it's hard, remove the clamps and pull the nails.

Paint all the stringers with linseed oil. And everything else that won't be coated with epoxy. Some types of wood survive better with linseed, some with epoxy. I haven't quite figured out what the rules are. Do it in the shade. Sunlight will gel it before it has a chance to soak in properly, and there'll be nasty goop on your sticks.

The gunwale strips are too thick to make the bend at the front, so we're going to laminate and bend the ends with extra sheets of plywood to make a "breasthook". We might as well call the laminations "cheekpieces" while we're at it.

Mix up some epoxy glue as in step 6. Paint it on every mating surface. Stack up the laminations. Nail the tails of the cheekpieces through the deck into the gunwales. Bend the stack up at a pleasing angle. I think mine are 4" or 5" above the deck. Put a clamp on the nose. I propped the nose up on a folding chair. This tries to tighten the radius of the bend, putting all the laminations under good pressure. Try it with some sheets of cardboard to see how it works. For extra security, put more clamps along the edges. Pound some temporary nails if you think that's necessary. Pile bricks and car batteries on it for even more clamping gladness.

Put it in the sun to kick off the glue. Go to the beach for some boogieboarding.
When it's all set up, pull the clamps off and marvel at the excellence. Don't do it until the glue is really hard.

When you take the clamps and weights The piece will spring back a little bit. I tried to make both pieces the same but it doesn't really matter. One end swoops up 4", the other 3.5".

Cut a piece of 1/4" plywood to fit over the joint in the deck. Paint some epoxy glue on the mating surfaces. Clamp it down or put a sandbag and car battery on it til it cures.

I used up all the good sticks making the gunwales and stringers. I don't have anything long enough for the keel. So I'm going to "scarf" some good sections together. That means cutting them off at an angle to make a splice and epoxying the sections together. A scarf joint is as strong as the wood it's made from and flexes almost as well. People argue about how long to make the scarf. I usually do it by eyeball then check it so I have something to agonize over. I wasn't sure how thick to make the keel, so made two of them. The other stick will come in handy.

Cut the scarf on the tablesaw. You can also do it with handsaw, power planer, beltsander, disk sander, etc. etc.
Then I cleaned it up with my little wooden plane. I got it in Japan for $10 or so at a "Cainz Home" superstore. High quality tools are really cheap in Japan. This one came with a sticker showing how to adjust the blade and keep the plane in your shirt pocket.

Cut a plastic bag flat and lay it on a scrap board. That will be the backing board to keep the scarf straight. The plastic bag keeps your scarf from getting glued to the backing board.
Paint thickened epoxy glue (step six) on the mating surfaces.
Mate them.
Pound one nail in to keep them from sliding. Clamp the hell out of them. Actually with epoxy you're supposed to avoid getting a "starved joint" from overclamping. In reality nothing is flat enough to do this. With other types of glue you want a perfect wood-to-wood fit.

That's it. The Scarf Joint. This is the magic that makes modern crap wood from our pillaged forests into something you can make boats out of.

Now that I'd ripped all my good wood down to make strips, I wanted some wide chunks to make the stems. Stems are the vertical boards at the front of the boat that define the chisel shape there.

I only had a couple of clamps with enough span to grip the assembly. So I wrapped them with wire and pounded in wedges to clamp them together. It worked great. The wedges were left over from cutting the scarf joints.

I agonized over the shape of the keel. I didn't have my notes from the Marshall Islands with me.
I finally decided on 23" from the underside of the deck to the bottom of the keel at the middle and 17" at the stem knuckle (where the keel line meets the front line of the stem). 45 degree raked stems.
I made some tee shaped jigs to support the keel and stems. The middle jigs are 22 5/16" tall and the jigs at the ends are 17.25" tall
For double-entry prose purposes, the keel has 6" of rocker (curve). The boat is 16' long at the deck and about 13' long at the stem knuckles.

First I set up the keel on the jigs and lashed it into shape.
Then I rough-sawed the stems and eyeballed them to see how they were. I tried different angles of stem rake.
Then I traced the curve of the underside of the breasthook onto the stem and cut a mating surface. When that was tight I did the same thing where it met the keel.
I slathered up the mating surfaces with epoxy glue.
I countersank and put permanent screws through the breasthook the stem. I used stainless flathead square-socket drive screws. They have a self-tapping thing on the front which is nice, less likely to split the wood they're driven into.
I did two different versions of the stem-keel joint. The notched one in the first photo is much better.
I put temporary screws into the sides of the stem to lash the keel while the glue dried. I pounded wedges under the lashings to make it extra tight. I countersank and put permanent screws through the keel into the stem.

When the glue was hard I took the clamps and wedges off. The end with the simple stem-to-keel joint started to pull apart, so I re-lashed it til the glue was truly dry.

"Aka" is polynesian for the crossbeams that go from the main hull to the outrigger. If you are using it in polynesian, plural is "kiato". If you're speaking gringonese, plural is "akas". Don't worry about it.

I cut a pair of 10 foot 2x4s down to make mine. Again, that's U.S. Weasel Association measurements, so a 2x4 is 1.5" x 3.5'. I drew a line and cut them freehand on the tablesaw. They are 2.5" high at the hull end and 2" high at the outrigger end. They'll fit in sockets in the main hull.

To make the sockets I sawed square notches all the way through one of the gunwales. Then I made a matching notched board to fit over it, glued and screwed it in place. I didn't have enough gaping clamps to do the job, so I used rope, sticks, and wedges instead.
Then I glued a strip of mahogany on the edge of the deck to keep the akas from busting up out through the deck.

The 1/4" luan deck is a little too squishy to walk on. I looked at plans for Tom Blake style paddleboards made from the same stuff. They seem to put a deck support every 5" or so.
I cut some western red cedar (WRC) into strips.
Then I cut square notches in each stick.
The notch will go against the deck and will allow water to drain out when the boat is upside down.
Otherwise water would pool between the sticks and you wouldn't be able to pour it out. That's a big pain in the neck.
The sticks aren't quite straight so I cut the notches in the arched side to make clamping easier. Also a slightly crowned deck is a good thing. I set the sticks in the sun to warp a little and enhance the arch.

I used the saber saw to plunge cut and cut out two cockpit holes in the deck.
Glued my little WRC deck beams across at the front and back edge of each cockpit hole.
Cut redwood blocks to support the sides of the cockpit.
Cut teak strips 1/2" square and glued them to the top of the deck.
I used all my clamps. That's one of the observed rules of boatbuilding. You will always use all your clamps.
Notice the deck beams by the aka sockets. Besides strengthening this area they'll help guide the akas into place.

Max tries out the cockpit. It's exactly the right size.

Here's a picture from the panic pamphlet on airplane that brought us here. It pretty much captures the feeling of sailing at sea at night. Soon we'll be headed there in our own boat. Time to get back to work.

Continue on to the next chapter: Make Some Ribs and learn assorted random wisdom.