I'm glad it was too cold to canvas...

[patrick corry]

And besides, I still have stripping to do as well. But over the winter, while we had single digit temperatures, I had some new rib failures. While recently looking over the canoe in anticipation of warmer temperatures I discovered these fractures; there is fresh wood visible within the breaks so I know they aren't old breaks. I'm wondering if it was just the cold, or if my previous rib replacements and planking had introduced new stress into the canoe? The four ribs are indicated by the pink painters tape. On close inspection I suspect the new tacks played a part...

 

[Gil Cramer]

It takes very little stress to crack old 1/4" ribs. The new tacks also helped.

 

[1905Gerrish]

Pat,

Don't hesitate to pre dill the holes for the tacks (of course not to big). That has happened to me over the years but not 4 in a small section like this. Dry brittle wood and certainly at the bend with freshly added stresses. I've had ribs crack on my old Gerrish's just from moving and twisting them. Heard them pop!

 

[patrick corry]

Don't hesitate to pre dill the holes for the tacks

Oh, I do pre-drill often. Always at the ends of planks for sure, and often at 'stressful' spots like heavily twisted planks. This section of the canoe is a puzzle as to why it happened. This poor canoe has been flipped back and forth for ribs and planking repair, not to mention the stress of highway speed travel from mid-Hudson Valley to Pennsylvania with lots of pieces missing- 70 mile an hour winds whistling through the canoe! It's think it will feel better once wrapped in the firm embrace of new canvas!

 

[Rollin Thurlow]

I would bet a pound of canoe tacks that the cracks were introduce when the canoe tacks were being clinched. If the iron needs to be exactly centered over the tack with the surface of the iron firmly on the wood. Being real close is not good enough. If there is any space between the wood and the iron the wood will "bounce" when the canoe tack is being hammered. This bouncing can crack the old wood. Its most often seen at the turn of the bilge where most people find getting the clinching iron positioned the most difficult.
Normally the cracks aren't seen right away but after the canoe is moved around a bit they start to show up. Your lucky they weren't hidden until you started to do the varnishing which is when most people discover them.
Predilling will help with preventing the rib from splitting but the hammering is what will crack the rib.

 

[dtdcanoes]

Pat, I just noticed that the canoe had not been stripped before the work began. I wonder now if the wood was so dry as to make is quite vulnerable. The long and short is the curve on the iron absolutely needs to be in contact especially if not predrilling. The curse of the last strike for the clinch is the bugger. If you use the iron sideways on the rib at least you have a chance . You are lucky at this point.
Dave

 

[patrick corry]

Certainly possible that it is user error! It can't be a faulty Northwoods Canoe clinching iron after all...

I have had a hammer in my hand my entire adult life as a carpenter/builder, but it's certainly possible that I wasn't always mindful of the contact issue. I never gave that 'gap' issue a thought with regard to potential damage. Thanks for the insights.

Dave, I didn't strip first because the canoe was just so damaged and flimsy I thought it best to make repairs first. Also, I figured that the stripping sludge might just impart some color to the new wood during the process; we'll see how that works out!