Tacks are proud - I'm ashamed!

[Brad Fisher]

A year after putting the final coat of paint on my 1927 OT Double Ender, I'm looking at tack heads pushing up under the canvas. Bummer! Obviously I didn't clinch them enough. Rookie mistake!

The thing is, I'd swear those proud heads didn't show when I canvased, filled and painted. The final job looked smooth as silk. So what gives?

Full disclosure, I used Chil-Seal water-based filler instead of the traditional boiled linseed stuff. Did the filler shrink down? Did the tacks work their way up?

And of course, is there a fix, short of recanvasing?

BEFORE: No hint of the horror beneath.

ONE YEAR LATER: Dimples of DOOM!

 

[Dan Miller]

I experimented with Chil-seal many years ago, and experienced the same sucking-in of the filler that can be seen in the lower right quadrant of your photo, highlighted by the reflection of the light bulb.

I stopped using it thereafter.

 

[Dave Osborn]

I had that happen once. Because it was a customer canoe I took the canvas off to find that the bumps were caused by varnish that squeezed between the planks. Feel along the plank seem to see if the bumps are along the seam. Either way it’s is unsightly, but it’s in the water so nobody will see.
From that point on I never varnished a a canoe with the canvas on.

 

[Rod Tait (Orca Boats)]

Odd that they are all in a row or maybe you are only showing one area. I suppose you could try to re-clinch them. When this happens to me on old canoes that have old tacks that I just missed re-clenching before canvas, I use a sledge hammer on outside and hit clench side of tack on inside. And if you dent the canvas, might I suggest that you add some high build primer paint over the outside and sand smooth and re-paint rather than re-canvas. You must not live in a place that sees a lot of sun. That canoe hull must get pretty hot in the summer on top of your vehicle and does that have something to do with the issue? Anyone?

 

[Craig Johnson]

I had that happen once. Because it was a customer canoe I took the canvas off to find that the bumps were caused by varnish that squeezed between the planks. Feel along the plank seem to see if the bumps are along the seam. Either way it’s is unsightly, but it’s in the water so nobody will see.
From that point on I never varnished a a canoe with the canvas on.

So I was reading this thread this morning and I thought “gee I have never had that happen and I often put at least the final coat of varnish on after the canoe has been canvased.”
An hour later I am out in my shop doing a light sanding on my Peterborough Cruiser before the final coat of paint and sure enough I see a row of bumps along every plank line on the bottom of the canoe. On this boat I did 3 coats of varnish after the canvas was on. I was particularly careful to work varnish into the cracks because it makes the white canvas showing through the cracks disappear. Also some of the cracks were a little wider than on other boats. I think those factors were what caused the problem this first time for me. They are not very noticeable and will be less so with the less glossy final coat, although I expect they may get worse since the canoe is about as dry as it will ever be and when it gets wet the gaps may close up some and squeeze out more varnish. Oh well, lesson learned, I still learn something new on every one I do.
Luckily this is my own boat that I am repairing to use specifically for tandem wilderness tripping. You notice I said repairing and not restoring. Sometimes it is nice to make a canoe as close to original as possible but on occasion I have just repaired a boat to a useable condition often for a specific use which may require modifications that do not match the original boat. These may involve moving the seat and thwart locations. In these cases, since it will be set up differently than originally, I am not so worried about mixing new and old screws or highly polishing all the brass or replacing the proper decals. It is satisfying to take a busted up old canoe and make it a functional working boat and not a show piece.
Example below is my 14’ Peterborough Mermaid that I moved the thwarts and seat to set up for solo tripping. Anyway, my 2 cents.
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