Never seen damage like this before

[rbudge]

The pictures show only part of the damage. Here's the story: the canoe is a very old Bastien Bros "Huron" 16. I've had it for over 20 years. I re-canvased it in the spring of 2018, replaced outer gunwhales, replaced the centre thwart with one better fitted for carrying. At that time, I was living in Labrador and though there is a lot of precipitation, most of it is snow and humidity is very very low through the winter. When I put the canvas on the canoe, it had dried to the point that there were gaps in the planking of nearly 1/4". A lot of the planking is spruce or pine I installed 20-something years ago after damaging the original cedar tearing fiberglass off it. It's all 4" plank.
Then we moved to Nova Scotia. The canoe spent the winter on a pair of sawhorses, well covered with a tarp and I did not even look at it until a month ago. The canvas was torn at both ends and pulled out from under the gunwhale in a couple of locations. The pipe lagging filler had cracked and crazed almost everywhere from the stretching.
The only possibility that I can see for the source of the damage is from the canoe woodwork absorbing water from the air and expanding. When I pulled the tarp off and turned the boat over, it weighed 20 to 30 pounds more than it did last fall and the planking was all tight to the point that seams were bulging very slightly under the canvas. So I believe the plank expanded to the point that it ripped the canvas.

 

[Dan Miller]

Two possibilities - the planking is most likely flat-sawn, which is inherently much less dimensionally stable than quarter-sawn planking, and, based on my own experiences, pipe lagging compound (the US Childers version of the Canadian Bakore) ended up not being a great solution. Admittedly, I've lost track of the canoes I used it on so I don't know the long-term effectiveness, but my short-term results were not great.

 

[rbudge]

Dan
You are quite right about the plank grain orientation. I sawed that plank out of whatever construction leftovers I had saved. The original builder built with 4" plank, so the replacements I installed were 4". If I had used narrower plank and introduced more seams, more expansion space, this problem might never have occurred. It's worse at the ends where the planks are close to being in a plane. Through the middle of the boat, the plank could force itself outward, the circumference of the curve would not increase much and there was no canvas torn.
I've had the canoe indoors for a month or so now. It has lost weight, gaps have appeared in the plank seams. I eased off the tops of the brass stem bands and added patches over the tears, bedding them and covering them in pipe lagging compound, then replaced the stem bands. My repairs do not go under the gunwhales, which is a pity, but that was more work than it was worth. I wiped a lot of the surface with lagging compound, which filled the micro-cracks, then painted with Tremco rust paint.
I don't think the lagging compound contributed in any way to this damage, either good or bad.
The surface of the canoe is no longer as smooth as I like it, but I'm sure it's watertight. I'll be out tomorrow or Saturday. I wonder if the roughness will slow me down? My increasing age is part of the equation too, but it will be a sad day for me the first time one of those tub toy plastic kayaks manages to pass me when I'm in that canoe alone.
Have a good 4th of July!
Ron

 

[davelanthier]

I have used the lag coating for many years as have my previous mentors without any comebacks or issues.
I wonder if preservative was applied to the canvas before the lag coating was put on. The canvas can rot quickly without.

 

[rbudge]

As far as I am able to detect it, there is no rot. The filler used on the canvas had no effect on the outcome.
I have another canoe, a Chestnut "Fort" Prospector stored in the same way right beside this one. Its canvas was installed a year earlier, in 2017. Conditions were the same. I canvassed the canoe in ultra-dry conditions in Labrador and then brought it south to Nova Scotia. It shows a small amount of superficial crazing, but no tears and the canvas has not been pulled out from under the gunwhales. The Chestnut is deeper than the Bastien and so there is more wood edge-to-edge, so one might think there is more potential for trouble. However, the Chestnut planking is narrower, so there are more seams to take up movement, and the Chestnut's plank is still all cedar, which moves less than spruce or pine in the same conditions of moisture content.