Re: deck leak
A mid range Divinycell (H80) has a compressive strength of about 174 PSI (http://www.fiberglasssupply.com/pdf/core/hmanm.pdf)toggle quoted messageShow quoted text
End grain balsa core has a compressive strength of around 1,837 PSI according to this site.(http://www.cstsales.com/end_grain_balsa.html) Balsa does vary in density but this is a huge increase over any foam that I am aware of. (http://www.cstsales.com/end_grain_balsa.html)
In general, polyester resins create a fairly low secondary bond. The balsa soaks up the resin so that the bond penetrates deep into the balsa and and this can create an exceptional bond, even with polyester if the layup is done properly. It is best to float the balsa in resin before installing to keep the wood from sucking up too much resin leaving a dry joint. With a foam like Dinvinycell the resin does not soak into the product, it pretty much sits on the surface. If a core fails in it’s bond to the fibreglass layers or crushes from an applied load it is a structural integrity is compromised even if the foam itself is ok. Divinycell seems to bond quite well to epoxies used in aircraft construction but most boats are built with Polyester resins.
So yes, one has got to take care in keeping water out of a balsa core but there are some really good reasons to use this material as a core material in my experience so I do not fault Amel at all for using it. In fact so far I have not seen anything that I like better for core.
On Sep 21, 2020, at 6:29 PM, Arno Luijten <arno.luijten@...> wrote: