Standard of care for plank replacement

floydvoid

Enthusiastic about Wooden Canoes
Hello,

I'm back to work on a OT HW from the 30's. It has a hole blown in the side of it, about one rib wide. What is the standard of care for this repair?

I don't see a benefit to pulling the entire two planks that it impacts.

I saw someone say that a "three rib repair" does the trick, I just worry about bulging.
upload_2019-6-4_10-48-0.png
 
First, you're going to replace that broken rib. Secure the far end with ring nails, but the end near your crack can be temporarily held in place with a deck screw. Don't be in a hurry to cut off the excess rib tip. In this specific case I would do a 4 rib patch, not securing the 2 new pieces of planking to the same ribs, i.e. go forward from the hole by one rib on one piece of plank and back from the hole by one rib on the lower plank. After the planking is in place you can test for a bulge and either push the new rib down or pull it up to get the new pieces fair. Running a straightedge across both inside and out is a good check. TM..
 
I had a similar problem with my Bob's. Here is the post for that. http://www.wcha.org/forums/index.php?threads/a-bobs-special-followed-me-home-last-night.15438/
I in the end had to replace 12 or 14 ribs in the center. If you replace the rib while you can leave everything loose around the repair area(rib and planks). I ended up working the rib up and down against the planks until I could get it pretty fair. Then I tacked the rib against the rail and then sewed up the planks.
 
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What Tom is telling you can be seen in this image...the idea is to avoid allowing seams to line up with each other. Seams should always be staggered...like laying block or brick. The farther apart the seams are the better...so there really is no 3 or four rib rule, it's whatever it takes to get the seams where they need to be. Depending on where you are on the hull a two rib piece could be used....it's a judgement call based upon the location.
I would bend the rib before pulling the planking. You need the thickness of the planks to form the rib...you'll put your new rib over the outside of the hull to shape it...two ribs away (towards the smaller part of the hull) to account for the difference between the inside hull dimension (where the rib goes) and the outside where you are forming it. As you get closer to the stems on the hull the shape of the hull changes more quickly so you might form a rib or a rib and a half away from the location to get the right shape. The closer you get the shape formed the easier it is to install tightly against the planking.
I would install the rib (as Tom recommends) before doing the planking repair. This gives you the shape of the hull to work with when you replace the planking. I clamp the rib on both rails...nailing also would work, but clamping leaves it somewhat free to push up against the planks that are present to give it the correct form. I tack/clinch the rib in at that point except for where the planking will be removed.
If you are worried about the form, don't...steal the steam iron from the laundry closet and use that along with a wet cloth to steam/shape the wood before you clinch it in place.

This image is not exactly what you will be doing but it will show you how much you need to stagger your seams. For what I was doing I could have cut each board shorter than I did but then the seams would have been lined up.

IMG_20190328_154150723.jpg
 
And to keep it looking good so the visual impact of the repair is minimized, steal a piece of planking from up in the bow or the stern, no one looks up there and you can stain the replacement in that area.
 
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If the damaged plank wasn't in the chine, it would be easy to make scarf joints and glue them in with thickened epoxy. A good scarf should make the plank as strong as it was originally, so staggering the repaired joints isn't necessary. The chine planks cup around the ribs so cutting a scarf with that cup is more difficult and involves a lot of fitting to get it right. That's why I suggest thickened epoxy, to fill in the gaps you eventually decide aren't worth fiddling with. Below I show making the scarf on new planks with a wedge to hold a plane at the scarf angle. You could make a wedge the width of a chisel to make the cuts on the canoe.

You can get a replacement plank piece to cup like that with five or ten minutes of steam and use the canoe as a form. I used the plastic bag steaming method because I had it all for doing gunwales. It is probably overkill - a towel and hot water would work just as well, I bet.

IMGB9988 by Dave, on Flickr
 
And to keep it looking good so the visual impact of the repair is minimized, steal a piece of planking from up in the bow or the stern, no one looks up there and you can stain the replacement in that area.
Andre makes a pro tip! Always keep your scraps to reuse where you need a nicely aged looking piece. And moving pieces around...brilliant.
 
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