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!

 

[patrick corry]

Finally reasonable temperatures in the barn! Four new replacement ribs bent over the canoe, but two failures along the way; not a good ratio. The leftmost one didn't surprise me with its squirrely grain, but the right hand failure was unexpected. It had no obvious faults in the grain.

So, on to removing the broken ribs. How do you folks do it? I usually do this, grinding the clinches from the inside then removal is easy and no planking is damaged. The tack stubs are easily removed from the outside.

 

[samb]

I remove ribs by the same method as you.
I seem to have better luck with rib bending than you though. Last week I did 38 ribs for my new build without problems, and these were wth red cedar. White is just not available in the UK, unless you import it privately. The WRC I use is from Canada as UK grown is full of knots and grows to fast. It is a comparable cost to home grown Ash.
Sam

 

[MGC]

There are plenty of ways for steaming and bending to go off the rails. Generally, ribs are one of the easier things to bend, but if things are not just so, they could break. From time to time I have had trouble with stems. I was using some very old and a worm damaged cherry on some outside stems once that I finally had to give up on.
I notice that you are not getting the ribs to lay flat to the planking. That will leave gaps when you move them to the inside to clinch them.
Lurking here on this site is a premier bender of wood. He even offers up a DVD guide......it might be worth checking out. https://www.wooden-canoes.com/canoes/books-videos/

 

[patrick corry]

You may be mistaking the shadow under the slightly radiused rib edge for lack of contact. The light source is to the right of the picture. With the exception of a few random spots where planking is thinner (or adjacent planks are slightly thicker!), the ribs are in full contact with the hull. I can't slip a business card under them other than in those few random spots I mentioned.

I suspect my breakages were mostly due to haste- as well as the less-than-perfect grain. I only steamed for about 20 minutes once the bag was fully inflated. I do, however, think I have been more successful when using the wooden steam box for bending lots of ribs in one session.