A Photo & Discussion Forum for Wharram Design Enthusiasts
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I don't like this much and warn against it because of fatigue failure. The bent steel strip will flex, work harden and fail suddenly. Be careful!
Ian Bamsey said:
I don't like this much and warn against it because of fatigue failure. The bent steel strip will flex, work harden and fail suddenly. Be careful!
yup
Looking at the photos,the U bolt set-up is too close to the bow. Quite a lot too close, irrespective of the leverage from the long U section on these.
When working mine out, I saw this immediately as another problem inadequately dealt with/specified in the plans - sorry Wharrams.
I found the longest U-bolts (ie their tails) I could buy in A4 10mm diameter, placed them well back from the bow extremity, about 70mm. Drilling and fixing for them was quite difficult. It's all by eye. On the outboard side on my boat, the plate is countersunk into the side entirely, but even then there's at least 50mm of meat behind the plate, and when I made the stems I laminated them very strongly, so it's at least 50mm of lam ply/epoxy on there between the nuts and the outside, not just ply.
On the outboard side I then cut in for some 6mm tufnol cover plates which are masticked in, so I can remove them easily when I like and inspect the bolts/washers/nuts for corrosion etc. (TIKI 31)
A wrap-round ss plate might help I suppose on some set-ups, as has been said.
I was quite annoyed about this detail, glossed by Wharrams: the U-bolt parameters should have been clearly stated.
Rogierio,
You may try to redo it with a back plate in order to i crease the tension area. Also, the angle made with your u bolts is not in the working direction. May be shorter u bolts could be a good idea.
To repair, I would try to ask Wharram, but I thinf that cutting the front on some 20cm length, as deep as possible, glue some plywood in place and re inforce on the outer side, either with anotoer plywood strip, or with a metal plaque.
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