Thanks for the good words and the advices.
I am uploading again the pictures. The first three ones show the actual setup while I was installing it. The last one shows its consequences (hull deflexion around the chainplates).
I also think a "mise en contexte" should be appropriate. It's my first boat and I have her since 2012. One of the first big project
I made was to replace the chainplates. The original ones were encapsulated in fiberglass
and bolted against glassed-in wooden knees. Even if I didn't know anything about it, I knew that the job was due to be done because the wooden knees were literally disintegrating between my fingers when touched them. At the time, I have also noticed flat spots on the hull
around the chainplates, but many person at my marina told me it was normal because there was no cracks in the paint
, and probably just a matter of hull
design (since then, I saw other boats like mine and realized that it really was a problem). So, I thought about it and arrived at the conclusion that it should be better for me just to grind out what was there and to reinstall the new chainplates only on wooden spacers with an external backing plate (see pictures). Of course it was a big mistake. I didn't know that the glassed-in wooden knees were also structural components to stiffen the hull and spread the load. The result is that hull deflection have increased since then, and this why I need to redo it another time.
I've learned by myself that structural questions are not easily answerable. Anyhow, it seems to me the original design wasn't up to the task neither (for both problems caused by encapsulated chainplates and hull deflection). Also, modifications (namely hole drilled through my hull for the mounting bolts) have already been made. This why I think I should try to keep what was good in my first project
(having the chainplates not encapsulated and the mounting bolts easily accessible for inspection/replacement if needed) and correct what I made wrong (not having thought of the structural role that the wooden knees were asked to play, and not having considered that my hull needed strengthening in this area). Of course I am not a specialist, but I am planning to work with Dave Gerr "Elements of Boat Strength" for all the calculation, formulas and as a general guide through the whole project. But I appreciate the remarks concerning security
- which should always be the first concern - and I'll keep them in mind.
Also, I want to keep an internal installation
Finally, thanks for suggesting other materials the knees could be made of. I'll think about it
Thanks to all and, again, I wish to have your opinion and hear about your experience.