My Peterborough wood and canvas canoe
My theory on this unusual canoe is that it is a Peterborough canoe built around 1910 on a Peterborough wide board form. Likely this was done when it became harder and harder to get wide boards. The weakness in the small amount of rib contact to planking was made up by the very large (2”) center keel and the standard size bilge keels. This does not solve the problem of the large gap and lack of support on the planking rib to rib. Thus, these canoes were prone to planking damage from even moderate impact on a log or rock. In this case, the canvas cover keeps the canoe from leaking but the resulting weakness is progressive. The canoe distorts and field repairs cannot fix it lacking the availability of the original form. Thus, I have a canoe much distorted and with many cracked, but not failed, planks.
Let me give some ideas…First of course…this canoe saw hard service, or, more likely, it suffered unreasonably from regular service. .
I count over 30 damaging hits (fractured planks) on rocks or stumps. A dozen previous planking fixes. Had to have been at least one re-canvas job even before the Fiberglas. I made the effort to pull the canoe back into shape but only mixed results. To really get it to shape I’d have replaced over 50% of the planking and ribs. But worse, I don’t have the form or any original thwart so I really don’t know the original dimensions. After all this time looking at the canoe I can say this:
Workmanship was professional. Scarf joins on the planking and really good nailing. All nails (no tacks) clinched. Decks are mahogany and made better than the typical Old town, i.e. more curvature and shaping. The 1 1/2 “ oak strip at the gunwale is significant. Never saw that but obviously gives strength where it is needed. Was it put there originally or later? It is closed gunwale as well thus likely predates 1920. The ribs are Peterborough style, ½ “ wide and 11/16 “ thick. Unlike standard steamed ribs these are three piece oak laminates with outer piece tapered to give the canoe tumble home. The planking nails held the three laminates together and I insist, it had to be built on a form to be of the consistent quality. I’d even argue, building this canoe without a form is impossible.
So who had that form? As I will outline, this is not a strong canoe. In fact, by design, it is a weak canoe. The weakness is so pronounced that I doubt a special form was built for this boat and likely an existing form was used. What kind?
Everything points to a Peterborough form. Half Inch wide ribs spaced 6 inches. This is similar to the wide board Peterboroughs. Take a wide board form, build without a keelson; Use oak for the ribs and laminate so they bend easier. You are using a good form, the nails will self clinch. The form only allows for ½” wide ribs spaced 6 inches. In spots you do not have a full length plank you have to scarf a joint for a single set of nails. No room in that ½” rib for a double row of nails like Old town, Morris or any wide rib boat. Again, scarfed joints sound like Peterborough. Greater skill needed.
A typical wide board Peterborough will have two, three, or four boards. They started out building with two boards and when the supply dried up went to three, then four boards. What next? This canoe has eight boards per side and the widest, being four inches, is used where the maximum curvature is outboard of the bilge keels. This is a very flat canoe.
When it comes off the form you have a cedar planked canoe, closed gunnel like every Peterborough, and just like the Old Town or Gerrish of Maine. Add canvas, and gunwale caps just like the Maine builders. All this on an existing Peterborough form. Do we have two options, two style of canoe now to sell? Yes. However……
The inherent design has flaws. In engineering, the strength of a beam varies as the SQUARE of the depth. The 5/16th ribs of an Old Town have a bending modulus of about 0.1 (.3125 squared). The Peterborough 11/16th rib has a bending modulus of about 0.5 (0.6875 squared). However, an Old town rib tapers from 2 1/8” to 1 1/8”. Average, 1 5/8” Peterborough rib, ½ inch over all. OT 1.625” width times 0.1 bending modulus gives 0.1625 strength modulus. Peterborough 0.5 width and 0.5 bending modulus gives 0.25 strength modulus. The Peterborough is 35% stronger in the rib on a deflection modulus basis. However, the OT rib covers 50% of the planking space in the canoe. The Peterborough covers 8%. The stronger rib of the Peterborough is lost by the scarcity of rib to planking surface ratio. OT has over 6 times the rib surface facing the planking. My canoe is intrinsically weaker in terms of twist and longitudinal planking fracture. The journeyman canoe maker knew this as soon as it came off the form. I have to keep a 2 x 12 on the saw horses just to work on this boat. It will not really support itself under load. How to fix the weakness? Add a big keel, two inches wide and perhaps two inches deep. (I have no example, not even a scrap) keel. Obviously, there is still a weakness the builder can feel. The bilge keels are added hoping to fix the inherent design flaw. There is still a 5.5” gap between ribs. This is too much.
Short summary: Canadian “wide board” builders responded to the shortage of wide enough boards (and competition from Maine builders) by making a few canvas canoes on the existing forms. They borrowed heavily from Maine builders and made several canoes this way? Field experience showed the canoes did not have the necessary strength even with an oversize keel and the extra two bilge keels. The effort failed and the canoes made slowly disappeared.
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