: Basically it will be a 4m aluminum frame with HDPE cross sections,
: Inflatable sponsons in the flanks, and a 18oz. (HH-66 glued) PVC
: hull.

: I would appreciate any feedback on my plans (which are attached to
: this post). I have a few questions too that I have struggled to
: find good answers for, like:
: 1.) Is there an easy way to work out the Gunwale length (before it
: is bent) or is it a case of trial, error and adjustment?
: 2.) Is the recommended load of the commercially available canoes
: dependent on the strength of the craft, overall buoyancy or a
: combination of the two?

: Any help with those would be great too!
: Thanks, Ben. (apologies for the long post.)

I looked over your drawings and have but a few comments.

1. Gunwale length will be determined at time of building on a strongback. On a 17' X 21" kayak, the curvature of the gunwale will add only 3" or so to the length.
You mention bent , I assume you mean taking the curve and not actually machine bending the gunwales, which is not required.

2. Load is normally a function of displacement, not so much a factor of strength, which is not normally going to be an issue. My Sonnet double
appears very light in structure, and has a quite flexible frame , but easily holds over 500+ lbs on the water. A fully loaded , flexible , lightweight SOF
sitting in the water is not like a fully loaded SOF sitting on 2 sawhorses... a common misconception regarding strength and buoyancy.

3. Use more chines on a wider taller boat like yours for frame rigidity. As drawn, your gap between keel and chine is too wide.
resulting in a sluggish performing boat. Sponsons will act as chines, but I don't see their location in your drawings.

4. Telescoping stringers are problematic vs simply using inserts as the farther you insert one tube into another, the
greater the chance for them to "freeze up" whenever a burr or scratch gets on the tube... and it will. The gap between tubes
will be very tight, and that makes them very susceptible to sticking together when telescoping. Pay close attention to the wall
thickness of your tubing as that will determine whether or not thay will fit together properly for telescope , or inserts use.
Also, know what grade aluminum you are buying as all tubing is not created equal.

5. Look at the "Pakboat" site frame pics for more frame ideas. They are sponson oriented ( 3 per side) hybrids, but use multi-stringer floors.
I prefer multi-chines vs multi-stringer floors, but either will suffice.

6. Consider making an inexpensive wood frame rendition "non-folder" of your design for testing with a plastic wrap skin. You can lash it together so
that the materials can be reused when making mods to the design. Wood folders, on the other hand, requires much more complex hinges and connector
hardware vs simply using an insert between aluminum tubes and snap on technology. As a homebuilt non-folder, wood is fine.

7. Folders share a lot in common with non folding SOF's, but are considerably more complex to design and build. Keeping it as simple as possible is the key to
success in homebuilt folder construction.

Have fun, Tom