Tarn - Lightweight Canoe Plans

Finally got around to drawing up the plans for my lightweight canoe, click the image for larger. Or even larger here.

As a quick disclaimer, this boat was built with absolutely perfect stock, no run out, no knots, so I was able to pare down the dimensions of the parts to the minimum. This means that if you have any flaws in your materials it would be advisable to upscale the parts accordingly. The same goes for the rest of the design, it has a minimum of ribs and a minimum of redundancy. Paddle it accordingly.

Usual restrictions apply, Commercial usage of this design is forbidden. Personal use is allowed, up to two boats, but no reproduction of the boat or this design in exchange for money or goods is allowed. Also, if you do build one, send me an email and/or some photos: dbynoe@gmail.com

Canoe Finished

Got my new canoe done. Still need to name her but details details. The shot to the right was taken up at Consolation Lakes, about 3kms into the backcountry from Moraine Lake, close to Lake Louise. Stay tuned for a video showing the trip.

Final weight came out around 15lbs for the boat, a little more than I wanted but still about 30lbs lighter than your average rec boat. I ended up adding a couple extra ribs in the middle to make it a bit stronger, probably could have gotten away without them but now its pretty much bombproof.

By the time I get my drysuit, lifejacket, throwbag, paddle and bailer loaded up my pack ends up being around 30lbs total, including the boat, so its pretty easy to carry in for any reasonable distance.  

Some construction details:

To skin the hull you basically just drape the fabric over, clamp it to the gunwales and sew the fabric together at the ends. For this boat I sewed the skin on wet and a little slacker than normal, I was afraid of the tension distorting the light frame.

Detail of stems. The stitch is basically just a saddle stich with two needles for the first pass. The fabric is then trimmed close, and the ends are folded under with a double whip stitch.

To attach the skin to the gunwales I had to get creative. Normally one would staple the skin to the outer gunwale, then screw in a rub strip to cover up the staples. This method is fast, but I didn't like the look, or the extra weight.Instead I drilled holes along the inner gunwale. These were drilled at about a 45 degree angle so they came out at the bottom corner.

The skin is pulled taught over the gunwales (while wet) and sewn through the holes. The top edge gets cut and I run another row of stitches to lock it back. Unfortunately this method means that I have to sew the entire length 4 times. I think it looks cool though.

Whenever I got to a rib I just skipped over it. There is enough tension on either side to keep it taught.

Same deal with the thwarts.

I ended up coating it with that same goop from the skin boat school that I used on my other kayaks. Its a two part polyurethane and goes on pretty quickly and painlessly.  You can see how translucent it is, that blue stuff is the waterline.

New Lightweight Canoe

Its been a busy last few months, been working at Street Characters Inc. building mascots. Spent my evenings working on a wooden drawing machine (should upload some photos of that...) and yet another boat for my fleet. This ones a canoe, and I am working to keep it under 15 pounds so I can carry it into backcountry mountain lakes. The complete frame is to the right, it came out at around 10 pounds (4.5 kg). Which is not bad for an 11' boat

Its been a fun boat to build, to keep the weight down I had to use the clearest straight red cedar I could find. The stems and centre thwart are red cedar, and the ribs are local ash wood I got from Drew Beatie, who runs a portable bandsaw-mill.

For those wondering how you build something like this, read on.

This is all the cedar stock, I start by running it through my bandsaw to rip it down to size. I dont have a jointer or a thickness planer so I hand plane all the pieces down smooth. I also dont have a carpenters bench so I use a 2x6 stuck in a workmate and resting on a saw horse for a planing bench. It works great.

This is the creation of the stem pieces (the curved bits at the bow and stern of a canoe) They need to be really strong as they are what you tend to run into things with. I took a piece of yellow cedar, roughly 2.5x3cm and ripped it into thirds. The pieces were then steamed, and bent over a form together.

They hold their shape pretty well once steamed.

I then glued them together with PL Premium construction adhesive. Use a lot of clamps.

The end then gets scarfed into the keel stringer. Most sane people use a table saw to do this. I don't trust mine, so I use a sliding miter saw. Cut a piece of scrap at 45 degrees, and clamp your piece to that. With a bit of futzing on the set up you can get a really accurate 8:1 scarf cut. Just be advised the the offcuts will launch, fortunately away from you.

Installing the stems onto the keel stringer. It would probably be wise to drill a couple dowels to keep the two parts from sliding while you glue them. Learning is fun.

These pieces are the breasthooks for the bow and stern. They attach the ends of the gunwales to the stems. To make them use a sliding bevel gauge to eyeball the angle that the gunwales meet the stem at, average all your measurements and take your best guess and set the miter saw to that.

I tape them up so I dont have to clean off the glue, and then just glue and peg them in place.

This is how you rip long stock in a very small and messy shop. I set up my bandsaw in the middle of the garage so then I can use my miter saw stand as an out-feed. It works better than those roller stands as you cant tip a mitersaw stand over easily. Here I am ripping thin stock off a big hunk of green ash for the ribs.

Once ripped, its back to planing, by hand. Someone finally told me to stick a block of wood at the end of the bench for the piece being planed to rest against. Previously I was clamping the wood down. The block of wood makes life so much easier.

Here is the hull blocked up with temporary ribs. These were left over from a previous experiment at making gluelam ribs. I learned that if you overclamp epoxied joints you squeeze all the glue out. Resulting in a useless rib for a functioning boat, but it works great as a form.

The ribs were steamed and shoved in next to the temporary frame. This was my first experience steaming green wood, and hallelujah I have seen the light. After 15 minutes in the steamer you can pull these out and bend them into a 3 inch radius with no problems at all. And this is 3/8" thick ash wood.

The hardest part of building this boat was working out all the little details, so here is a few shots showing some of the more tricky bits and how I worked them out.
First, this is where the stringers meet the stems. I cut them off at an angle to match the surface. Then tied a couple constrictor knots around the stringers. These keep the lashing from sliding off the front, I then wrapped around both stringers, made a couple frapping turns to secure it, then did a couple loops around the stems.

This is the mini thwart at the bow and stern. I added this piece in because I felt the boat needed a little more wood to keep the gunwales from spreading. Its a simple Y lashing through a hole drilled in the thwart. You can see how the inwale and outwale are also secured with a lashing to hold them together.

The centre thwart is lashed in much the same way. I added in a block of ash between the thwart and gunwale to help spread the load, red cedar is really soft wood. This joint isn't pegged or glued, the lashing holds it in place just fine.

Shot of the final stem piece. The breasthook is glued to the gunwales, but only lashed to the stem. I wasnt sure what to do with the inwales so I just cut them off and lashed them to the outwale.

Stem from a profile view, you can see the scarf joint on the keel stringer. I should probably put a couple lashings on it to secure it.

The complete frame.

For you detail nuts, the dimensions of all the pieces are as follows: (all units cm)
Gunwales: inwale: 1.1 X 4 outwale:1.3 x 4
Stringers: 1.5 x 1.7
Keel stringer: 2.3 x 2
Floorboards: 4 x 0.9
Ribs: 2.6 x 0.9
Stems:2.4 x 2.2
Centre thwart: 3.3 x 2.2 in the centre tapering to 3 x 1.7 at the ends.
End thwarts: 1.1 x 1.77

The overall proportions of the boat are 11' long and 28" wide, its 13" deep amidships and is slightly wider aft of centre.