No form needed
Tim –
Check your private messages.
Not much of a building form would be necessary to build a canoe like yours. Indeed, it could be readily built with no form or mold whatsoever.
A Trailcraft canoe had three or four plywood frames/ribs plus two plywood stems. The frames/ribs and stems were held in position by the inwales and the keelson – these pieces, in effect, becoming the building form. The stringers were then installed, the canvas was stretched and fixed in place, and the keel was screwed on. To the best of my recollection, no strongback was used – the keelson served as the starting point, to which the stems and frams/ribs were attached, with shape and symmetry being provided by carefully-measured placement of the inwales.
The 1938 PM canoe is built with a form using 7 hull molds, the 2 stems (built up from plywood and sawn lumber), fixed to one plank that served as a strongback. Ribbands (temporary stringers), a keelson, and the inwales are placed in or on the molds and stems, then steamed ribs are placed inside of, and clamped to the ribbands, keelson, and inwales. When the ribs are cool and dry, the ribbands are removed and the planks are fastened to the ribs and stems. There are many more ribs than there are station molds for the hull.
I would speculate that your canoe was built by some combination of these techniques. A form with several molds could have been used, to hold ribbands in place while the ribs were shaped and installed, after which the ribbands were removed and the permanent stringers then fastened to the ribs. Alternatively, and I would think more likely (since fewer temporary framing molds and ribbands woud be required), 3 or four heavy temporary molding ribs similar to the Trailcraft ribs could have been fashioned, then temporarily fastened to the inwales, keelson, and stems (or perhaps temporary stem frames). The stringers would have then been installed, after which the temporary molding ribs would have been removed. Depending on where the temporary molding ribs were located, it may or may not have been necessary to replace them with permanent ribs. The framing stems could have been the permanent stems, or they could have been temporary, to be replaced with the permanent ones at this time.
I would be interested in seeing a detail photo or two showing how the stems are built in your boat.
With a good set of plans, construction would probably have been relatively simple, and may have required nothing more than building a few simple temporary framing ribs/molds\, perhaps with a strongback.
A kit certainly would have been possible, containing not only the canvas and wood for decks, keel, keelson, gunwales, and stringers (as did the Trailcraft kits), but also the temporary molding ribs, just as the Trailcraft kits contained the three permanent framing ribs for their canoes (one of which I built many a year ago). If a strongback were required, I would expect the seller of the kit to presume that a local lumberyard could provide a satisfactory piece or two of dimension lumber.
It must be noted that neither strongback nor molds nor a frame are really needed. Robert Morris gives instructions for building a 16’ skin on frame Canadian canoe that has 20 thin, steam-bent ribs, and his technique requires no mold, no shaping frames and no strongback. His book “Building Skin-on-Frame Boats” is a well-written guide to building SOF canoes, dinghies, and of course, kayaks – all without the need for forms. Shape is created and held during construction by thwart-like temporary braces between the gunwales. I would recommend the book to anyone owning, or wishing to build, a canoe such as yours.
As I noted above, the way the sheer is shaped at the stems is of great interest, and solves a problem of hogging that can too easily develop in SOF boats that do not have longitudinal deck structures as have kayaks – a problem described by Morse.
Anyway, I would hope that plans do exist for this canoe, and that someone has a set of them that can be shared in some way.