Fibreglass and ageing

[vyv_cox]

Re: More stress out of the water ?

I think you may well be right about the stress met on the hard, but it's all beneath the antifouling and doesn't show. The places on my boat where crazing is evident are virtually all at point where flexing is likely - stanchion bases, junction of deck and coachroof, etc. One or two are not so easy to understand and I wonder whether a little torsion has been applied by uneven loading on cradle supports.

 

[oldharry]

Re: More stress out of the water ?

Looking at my solid old boat and comparing it with the scantlings of most modern production boats, I have to wonder sometimes whether the 'accepted' standards for engineering a modern hull do actually build in a sufficient reserve of strength for the stresses not only of sea but of laying up. I remember some years ago seeing a nice 35 footer which had been dismasted: the stay itself and its fittings were intact, but around a foot of the steeply raked stem moulding had simply snapped off altogether.

Other than those laid down for Lloyds certification, is there actually any basic set of standards for yacht or boat cosntruction? Or does each designer/builder do his own set of calculations and hope that not only has he got it right, but has actually spotted where all the stress points are likely to be? With the many reports of stress failures in deck mouldings even to be found on these pages, it seems that under-engineering of mouldings is a common problem.

Then does the builder - with an eye to costs - actually build to that specification? Or does the moulder actually bother to build in all the required strengthening?