Planning new pirogue

[beekeeper]

I have a model on my work table that is very similar to yours. It is based on my last boat, the square stern pirogue built for my son. Yours will be a little narrower and his is tumblehomed to increase the side depth.
If I use the model to build for me I will increase the length 8" to 12". This will help compensate for my wider floor.
I like the sheer line ratio of 8" deep at midship to 11" or 12" at the stems. It has a nice curving flow. Unfortunately I am more comfortable with about 10" depth at midship. That would make the stems too tall. The tumblehome adds the height needed but preserves some of the nice lines and keeps the overall beam manageable. I actually like the looks of a non tumblehomed pirogue, but I would rather have an ugly boat and be dry than pretty and swamped.
The curved/near vertical stems are more pleasing to my eye than the pointed/raked forward look some designs have. That said function over form, I hope they are not an issue for you (beaching the boat. log jumping, etc.)

 

[jdupre']

More vertical stems do hinder log jumping a good bit and beaching a little bit. Both compromises I'm willing to make for a lighter, sleeker boat. Like I say, I like the 3D sculptural aspect of building a boat probably more than any other reason.

 

[beekeeper]

Doing some rethinking. If I'm planning on doing some epoxy/glass work anyway, I might just go ahead and tape and epoxy all the hull joints. I definitely don't want to do a whole inside/outside glass job. Taping the bottom and stem joints is really not too bad. Time wise, it's probably close to building with chine logs and wood stems. Epoxy/glass joints are very strong and the 1/4" ply is strong enough everywhere else. I could always put in a couple of ribs if it needs it. Still mulling it over.

If you filet and tape the chines but think the the boat still needs ribs would glassing over the outside add as much strength/stiffness as the ribs? Since you are already invested in the resign and glass, doing the outside may not be any harder than fitting a couple ribs.

 

[jdupre']

For me, I think adding the one rib I think I may need is a LOT easier than a complete outside glassing. I just don't want to glass, fill, sand, fill, etc. I'll see what kind of chine material is available and then I'll make up my mind. Building on the fly.......ya gotta love it!

 

[beekeeper]

I was not trying to steer you to glassing. Mostly wondering if the glass would stiffen it as much as ribs. I think it would help with the flexing of the plywood more than it would with the stiffness at the sheer line. Ribs, or gunnels, or tumblehome panels would probably work better for that.

 

[jdupre']

I don't think the all-over effect of glassing would increase the flexing strength of the plywood as much as the localized strength of a rib. There is hardly any flexing out close to the ends..... in the sides or in the bottom. One rib close to the middle is about all I've ever needed in my boats. At this point, Bee, you and I have a pretty good feel of what it takes to make a "strong enough" boat. That is different for both of us. My feeling is that a really stiff and rigid boat is slightly overbuilt. By how much is anyone's guess.