: And,the power of oars applied directly to the hull can be fairly great.
: Constructing an SOF rowing shell that is sturdy enough to take the abuse
: of oars being pulled with maximum force will not be easy. SOFs can survive
: in rough water because they flex when encountering outside forces. An SOF
: rowboat is also going to flex because of inside forces generated by the
: oars.
: If you build SOF kayaks that are paddled rather than rowed you will be making
: your design problems much simpler.

Hi Charlie,
If Alan, the original poster, was to go the way of a SOF open boat, a design similar to a currach in construction technique would not flex under oar pressure. The currach uses a double gunwale, one above the other, 6 to 9 inches apart, with stanchions between the gunwales, 12 to 18 inches apart. These are nailed in place. The ribs fit into the lower gunwale only and are almost semi-circular in bend. There's more stringers than even Alaskan kayaks have but not as many as a birchbark canoe. There's no keel as such, just another stringer the same as the rest.
A currach built for two men to row is light enough for the two men to carry easily.
They're fast but don't have as much inertia as a wooden hull the same size. Good for acceleration but they don't have too much glide.

Being designed/evolved for the Atlantic sea off Ireland, they'd handle the river waves mentioned fine.

Mike Savage
South West Cork