plans for square stern canoe

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plans for square stern canoe

Postby slick » Wed Mar 23, 2005 5:23 pm

so far i've been unable to find a set of plans for this type of canoe. any suggestions for a set of plans that could be modified to square stern? right now i am leaning towards the canadien because i like the classic peterborough lines.
i would like to build something that i can strap a small (2-3 hp) outboard onto for big lakes and still paddle on shorter trips. i've seen photos of grand laker style canoes and i think they are a overkill for my needs.
is there a set of plans out there i've overlooked? or would something other than the canadien be better suited to this sort of modification?
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Postby Glen Smith » Wed Mar 23, 2005 5:39 pm

Have you seen the Mini-Grandlaker?
If you just chop off part of the stern of an ordinary canoe, there will not be enough volume to support the motor and motorman without having the bow riding high out of the water.

One of our members modified a Bob's Special. His website is in French but pictures are a universal language. :wink Click on all links and you will eventually find pics of his boat in use.
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Postby slick » Thu Mar 24, 2005 5:48 am

thanks for the quick response.
i wish there were more photos on that page of the mini grand laker design. i don't know if plans are still available since all links to that page on the site have been removed...... i still tend to think that there is far more than enough flotation with a stern that wide to support the weight (although perhaps not the thrust, without modification) of a 5hp motor (roughly 55 lbs). something that wide in the beam and stern would almost need to be rowed, and i greatly prefer paddling to rowing.
i bookmarked jean-pierre's site a few days ago after i found it through google and thanks to their translator program was able to read it. it convinced me that what i wanted to do would work.
it's my understanding that very little of a canoe's flotation is provided by the pointed ends; the transom would be roughly where a side motor mount would be bolted so i don't think it should squat too badly with the motor (2hp, roughly 28 lbs) attached. proper transom angle should prevent the bow from rising too much under power.
the "muse" for this project is a peterborough square stern i saw photos of which is why i like the canadien, unless another design would be inherently better for this type of modification.
i am a first time builder so any advice and criticism is appreciated.
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Postby Kurt Loup » Thu Mar 24, 2005 8:14 am

I emailed Newfound WW a couple months ago about the mini grand laker plans. Their response was that they are revising the plans at this time. They weren't specific about what they were changing. If I remember correctly, they said it wasn't a scaled down version of the grand laker plans in the Gil Gilpatrick book.

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Square Stern

Postby Tom in MN » Thu Mar 24, 2005 1:35 pm

I think you can take any canoe and leave the stem station off, and build the last form as a permanent transom. Gilpatrick's mentions this in his book. I would take whatever design you think would work best, make the end station to be permanently affixed to the hull, (cut it to it's finished size, then attach a temporary piece of plywood to carry the station down to the strongback. Leave tape off of this station so the strips can be glued too it. Then fllip the canoe and wrap glass around the transom on the outside and inside corners and you have a square stern canoe. The one question that I would have is what type of wood to use for the transom? Plywood would probably work best, then trim off the top edge with a piece of harwood, and then affix a metal plate for the motor brackets so they don't dig into your transom .

I have never read anywhere that square stern canoes have different design characteristic, so this should work with nearly any canoe. Just make sure it has good stability because you will raise the center of gravity (bouyancy) with the addition of an outboard (you already know this).
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Postby Bryan Hansel » Thu Mar 24, 2005 2:39 pm

I remember see a free plan on the internet somewhere that had a squarestern canoe. If I remember right the language was Russian. Unfortunately, I deleted the bookmark (kicks self).

If you haven't tried this site yet you may want to look. I believe I found it from one of the links there.
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Square Stern Canoe

Postby Shuswap Pat » Fri Mar 25, 2005 11:54 pm

I have a 17' 6 Square Stern I built, using a 'Modified Prospector" design. I took the basic prospector offsets from Canoe Craft, scaled them up 7% to give me the width I wanted. I then placed the stations from midship forward at 13" instead of 12, and midship aft at 14". The hull finished at station 14, which was a piece of 3/4" plywood. This concept works, but it would be better to faire the stern in, for less turbulance. If you need more information, I think I have pictures.

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Postby slick » Sat Mar 26, 2005 4:38 pm

pictures would be great. post them here or email them:

if by fairing in the stern you mean a wineglass shaped transom, i had thought about this but i'm not confident in my ability to design one to a proper shape (something that the cedar strips could cope with, without twisting them beyond their limits) . i also thought that this might reduce flotation with the motor in place. i figured the turbulence would be the price to pay for having a square stern.

right now i'm looking at 17' plans, transom at station 14, 13" between forms would yield a boat about 16'. sound ok?
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Postby KARKAUAI » Sat Mar 26, 2005 6:32 pm

Has anyone considered making a motor well instead of squaring off the transom? It would allow puttering with a motor without changing the shape or bouyancy of the hull much. Would probably cause considerable turbulence, but ? maybe worthy of consideration.
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Problems with Square Stern Canoes

Postby garypete » Sun Mar 27, 2005 9:57 am

Before deciding irrevocably on the square stern for outboard use, consider three serious problems inherent in square stern canoes as opposed to a clamp-on side motor mount.

Ease of motor use
With a square stern, the motor is directly behind you and very close which makes it very uncomfortable to reach the tiller handle. Tiller outboards are designed for an operator sitting ahead and to one side of the motor so the tiller naturally lines up with one of the operator's arms. Also, think about turning around in your stern seat to pull the starting cord. You need to turn nearly completely around and come off the seat because the motor is right in back of you. Motors on a side mount have neither of these two issues.

Stabilty/torque arm
When the motor is suddenly cranked up to full throttle, there is a torque force that functions exactly like a gyroscope. If that gyroscopic force is from a stern-mounted motor that's directly in line with the overturning axis of the canoe, it's really easy to flip a canoe with a stern-mounted motor. On the other hand, a side-mounted motor has its gyroscopic torque motion well to one side of the canoe's long axis. When underway at full throttle, the side-mounted motor's gyroscopic force actually tends to keep the canoe in its upright position. The force is very noticeable and comfortably reassuring.

Displacement craft hull speed
The potential maximun hull speed of a canoe is directly related to the square of its waterline length. Cut 18" off the stern of the canoe and you have severely altered its waterline length and decreased its maximum hull speed.

Paddling efficiency/turbulence
This problem is tied in with the above problem of decreased waterline length. Unless you opt for doing a wineglass stem like the Grand Lakers, the suare stern creates lots of speed-robbing turbulence and greatly increases the paddling effort needed for any speed above about 3 knots.

The first canoe I built as a teenager back in the 60s was a square stern and had all the problems above. I finally ended up making a clamp on outrigger to stabilize the canoe so I could use the outboard.

Since then, I've used outboards many times with clamp on side mounts for Canadian fishing trips with fully laden canoes.I feel it's the only way to go.

You can make a nice wooden side mount for a couple dollars in a couple hours that will last a lifetime. Like Thoreau said, "Simplify, simplify, simplify."

When people figure out what's really important in Life, there's gonna be a big shortage of canoes.
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