Skin on frame solo canoe build, Day 4, part 2

Skin on frame solo canoe, Day 4) 7hrs.
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The biggest challenge when building open boats with skin on frame techniques is that without a rigid shell the framing members are always trying to spring back into natural curves that may not be desirable for the shape of the boat.
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One approach is to build a mold just like you would for any wooden boat and then wrap it in stringers and steam bend in the ribs. In my experience though, the boat that comes off the mold is rarely the same as the boat that was on it.
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For little row boats I still build over a mold (or laminate the ribs) but otherwise I prefer free bent methods for both speed and the fact that any shape that I can make is going to be a shape the boat can hold. Just like every building technique there are compromises and limitations, in this case not being able to add much tumblehome or make really deep square bilged canoes; but there are also considerable savings in the time and money that it takes to build a strong back and loft out a set of forms. I also love the ability to change the shaping and the sizing of each boat individually, which is really handy for rapidly evolving designs.
.
I designed the system I’m using here as a fast way to build nesting pack canoes, but before I even had the plans ready though there were a LOT of people asking if it could be used to build larger canoes as well.
.
It seemed like a bit of a stretch for free bent techniques but with careful attention to process it seems to be possible. To keep the tensions balanced I flip every other rib that comes out of the steam box and clamp opposite stringers on simultaneously working from the gunwale down to keep the tensions balanced. The symmetry is never perfect but it seems to be good enough if you start with really good bending stock.
.
The system gives me the freedom to change many variables and produce roughly the shapes I intend. The bigger challenge is just knowing what shapes to make in the first place! I expect it will be many years before I understand the nuances of full size canoe design to anywhere near the degree that I’m familiar with kayaks.

Skin on frame solo canoe Day 4, continued.

The biggest challenge when building open boats with skin on frame techniques is that without a rigid shell the framing members are always trying to spring back into natural curves that may not be desirable for the shape of the boat.

One approach is to build a mold just like you would for any wooden boat and then wrap it in stringers and steam bend in the ribs. In my experience though, the boat that comes off the mold is rarely the same as the boat that was on it.

For little row boats I still build over a mold (or laminate the ribs) but otherwise I prefer free bent methods for both speed and the fact that any shape that I can make is going to be a shape the boat can hold. Just like every building technique there are compromises and limitations, in this case not being able to add much tumblehome or make really deep square bilged canoes; but there are also considerable savings in the time and money that it takes to build a strong back and loft out a set of forms. I also love the ability to change the shaping and the sizing of each boat individually, which is really handy for rapidly evolving designs.

I designed the system I’m using here as a fast way to build nesting pack canoes, but before I even had the plans ready though there were a LOT of people asking if it could be used to build larger canoes as well.

It seemed like a bit of a stretch for free bent techniques but with careful attention to process it seems to be possible. To keep the tensions balanced I flip every other rib that comes out of the steam box and clamp opposite stringers on simultaneously working from the gunwale down to keep the tensions balanced. The symmetry is never perfect but it seems to be good enough if you start with really good bending stock.

The system gives me the freedom to change many variables and produce roughly the shapes I intend. The bigger challenge is just knowing what shapes to make in the first place! I expect it will be many years before I understand the nuances of full size canoe design to anywhere near the degree that I’m familiar with kayaks.