Are wooden pirogues safe and sturdy?

[mmelnick]

For anyone here who has ever built or been in a wooden pyrogue... Do they feel flimsy and flexible at all? I'm finally about to embark on my first boatbuilding mission, but I've been worried that something built out of 1/4" plywood might not be the safest.

Will the edges feel fairly ridgid like a traditional fiberglass canoe? Or will it creak and flex out on the water?

Also, would you recomend a small outboard motor, or is that asking too much for what it is?

[alan white]

You should find a pirogue to be quite stiff due to the flat bottom. It should be possible to stand up easily without fear. The traditional construction is usually heavy with full thickness boards for sides and bottom and no worries about flex. A better design would be to use 1/4" plywood and tape the seams. That would be light and considerably easier to propel and handle, and flex wouldn't be an issue if properly built.

[gonzo]

1/4" is actually quite stiff. It is possible to build them lighter.

[mmelnick]

I was planning on a good thinck transom. Probably a solid piece of 1" thick pine. Maybe even built from 2X dimensional lumber (so 1 3/4" thick).

Then probably 3 ribs built from 2X2's. One along the seam where the 2 sheets of plywood meet and another on each side cutting the boat into fourths.

Then on top of that I'm planning on taping the seams.


I wasn't really planning on any gunwhale reinforcement though. I'd like to keep the weight down.

I think I'll stick with this plan as long as there is no indication that the sides of the boat will flex or move at all.

My father in law said that he built a plywood jon boat in the 70's and it was really scarry. He said that he got out on the water and it would start to creak and flex. But I think he used plywood, 2X4's, silicone for the seams and paint. He didn't use epoxy or even poly resin.

His story ghot me a little bit worried though. So I thought I'd double check with you guys since you have a lot more experience with doing this sort of thing.

[mmelnick]

Originally Posted by gonzo

1/4" is actually quite stiff. It is possible to build them lighter.

Not the 1/4" luan that I can get.

It's nice and flexible, and the stuff that I can get has 3 EVEN plys without any voids at all.

I used a sheet for something else and even after cutting it in half down the middle it had no voids at all. So I'll be using that for my pirogue.

[gonzo]

If you want to keep the weight down, those scantlings are overkill. Ribs of 3/4X1 1/2 are more than enough. The transom can be framed with the same and then skinned over with 1/4" ply.

[mmelnick]

Originally Posted by gonzo

If you want to keep the weight down, those scantlings are overkill. Ribs of 3/4X1 1/2 are more than enough. The transom can be framed with the same and then skinned over with 1/4" ply.

Could I do the transom like that and still use an outboard motor?

How big of a motor could I use with this boat?

I didn't grow up around boats so this is all very new to me.

I did grow up doing a lot of woodworking. My parents owned a shop called Wooden Things where my dad made all of our inventory in the back room with a glass window so the customers cuold watch. I'm confident that I can build a simple boat like this. But I really have nothing to gauge my build by since I haven't been around that many boats.

I'm assuming that the transom thickness will greatly effect the use of an outboard motor? I wouldn't want anything big. Just something with a horsepower in the single digits. But even that's a lot for a 1/4" plywood boat right?

[mmelnick]

Originally Posted by gonzo

If you want to keep the weight down, those scantlings are overkill. Ribs of 3/4X1 1/2 are more than enough. The transom can be framed with the same and then skinned over with 1/4" ply.

Oh, and I'm assuming the 3/4" side would go towards the hull leaving the 1 1/2" side exposed right?

[gonzo]

The finish thickness for an outboard needs to be about 1 3/8 to 2". I have built a few small boats with a framed transom. I glue and screw a 3/4" board on the outside that goes from side to side and a filler on the inside for the outboard screws.

[Submarine Tom]

Mercury makes a 2 1/2 hp, four stroke with a built in fuel tank that would be great.

You may want to consider going electric, they're really quiet.

-Tom

[mmelnick]

Gotcha. So maybe a 2X2 (1 3/4" thick) frame for the transom with a 3/4" ply layer on the outside and a 1/4" ply layer on the inside to get me to a total thickness of 2" would be perfect for a small outboard.

Or just skin it with 1/4" and forget about the inside if not using an outboard.

Then use 3/4X1 1/2 for the scantlings and I'll have no trouble with creaking or flexing.

[mmelnick]

Originally Posted by Submarine Tom

You may want to consider going electric, they're really quiet.

Plus I can take them on a lot of lakes where gas motors are banned.

I've been seriously considering going electric for sure.

[alan white]

Lighten up that transom. Depending on transom width, with an electric outboard the transom can be 1/4" with a 3/4" board maybe 4" wide across the top inside. Width of board need only be wide enough to accommodate the motor clamps. An additional patch of 16 Ga.aluminum inside will allow the board to be a softwood for light weight.

[mmelnick]

Originally Posted by alan white

Lighten up that transom. Depending on transom width, with an electric outboard the transom can be 1/4" with a 3/4" board maybe 4" wide across the top inside. Width of board need only be wide enough to accommodate the motor clamps. An additional patch of 16 Ga.aluminum inside will allow the board to be a softwood for light weight.

With that setup could I still strap an 8-9 HP motor on there though?

[alan white]

Originally Posted by mmelnick

With that setup could I still strap an 8-9 HP motor on there though?

No, not necessarily. You should never overpower such a light boat. Boat speed will not increase hardly at all with the larger motor. Only planing hulls can take advantage of more power to get more speed. Three HP is way overkill, equal to 6 men rowing hard (without the weight of 6 men).
Yet that much power (8-9 HP) will still stress the transom about 10 times as much as an electric. You could certainly use up to a 2 HP and achieve top speed easily at half throttle.