Backside rib repair question.

1) How long should a backside rib repair be? I have a Thompson take-a-long wood canvas er-uh-rowboat. Planks are over 3" wide and two planks worth seem like enough. The ribs are 3/8" thick and 1 1/2" wide. So I planed some ash to 3/16" and figure I'll back-up those cracked ribs after taking material from the backside of the cracked rib.
2) And, does it matter if the repair is tapered or not in thickness? Or should the joint be 45 degrees or more accross the rib or an arrowhead shape? Don't know if the stiffer patch might make undue stress at the joint end if it is at 90 degrees to the rib. I shoulda' paid more attention to the prior posts about backside repair, but I couldn't afford to pay attention at the time.
3) Or--is ash too stiff/strong? Should I just use cedar?

thanks, Dave frozen in Lapeer.

 

Hello Dave,
I'm not much of a fan of the back side repair unless its for some historical reason to save the rib. But if you are going to do it ash would not be a good choice. It will be stiffer than than the other ribs just because of the splice and the hard wood will make it worse. Also the ash will start to rot in few years, its like a rot magnet. Well, maybe not quite that bad but bad enough.
The length of the splice should be at lest long four inches so to splice both sides would take a minimun of 8 inches and then the curve of the hull gets into the act and makes everything even more difficult.
Rollin

 

Thanks Rollin

I am using cedar for the backside rib repair. It seems to be going ok so far but I was wondering if there is enough strength to it.
Regards, Dave.

 

Hi Gil, thanks for the input. I have three staggerred repairs done on this rowboat so far. I am using Gorilla glue which is supposed to be flexible and water proof (resistant?). I believe every word Rollin and you say. I think I may have to re-do before I get too much farther along. I am not so sure the repairs are very strong.

 

Hi Gil. I am going to miss the QWS this year. I am the speaker at a wild game dinner and am talking about canoe building, outdoorsy stuff and mentoring. I'll no doubt get in a plug for the WCHA. I'll miss helping out with canvassing. Which raises a question. I wonder if WCHA has somthing I could print and hand out.

 

So, I was reading back through this old post and am curious about the above statement. I just do not understand why an epoxy wood interface would encourage rot anymore than a wood and varnish interface, I assume both epoxy and varnish are reasonably impervious to water, and would behave similarly (maybe I am wrong here). If it is true that the epoxy wood interface promotes rot, that would mean it is a really bad idea to ever laminate up stems in wood and canvas construction. Any thoughts anyone?

 

rot magnaate.

Hi, I used cedar for the repairs. I think that the ash would be the rot magnet. The epox would be stiff and maybe brittle and not flex with the boat. I have a theory about the 11 ribs I fixed. The ribs in this take-a-long are 3/8". So the patch is 3/16". The new wood, and this is my theory, in conjunction with the old wood probably is as strong as an unbroken old rib would be. The section came out fair. As a hobbyist I am satisfied that this way is the best compromise for my use. Sure glad I used cedar.
BTW I finally got the stringers in and after a couple coats of linseed/mineral I now have one coat epiphanes. Jamestown had a good deal plus a free brush on the epiphanes.
I've attached a photo. patches can be seen on the left side. (starboard).

 

Dave,

Wow, seeing that boat brings back memories We had one at our place in northern Wisconsin - my folks place. We kept it on the "small lake" for bass and pan fishing. It was pretty weak but didn't leak much. We fished it a lot. It was a sweet boat to row and stable fishing platform. Yes, nice boat for sure.

Jim

 

take along

The brass tag says Thompson Bros Boat Mfg Peshtigo, Wisc. My wife selected the Kirby Red for paint. So if Mr. Kirby is watching, I'll be calling soon. I hope to put the no. 8 canvas on it soon. The outside stem and outwhales will be new ash. The old ones are pretty beat up. I have some old oars for it and one long push pole that the ducks boats use. Wife wants a sail for it too. Did you notice the two canoe forms in the backfround. I am so lucky.