Composite / Fiberglass Chainplates?

[svaletheia]

If I'm doing the math right, based on (http://multihullblog.com/2011/01/composite-chainplates/) that if the tensile strength of laid fiberglass composite construction is on the order of 60k psi on the low end, this is in the same range as the ultimate strength of stainless, and if some carbon is added to the mix, that goes up significantly from there.

Since we design with safety factors compared to the yield strength of stainless, would this not imply that a composite chainplate has a significantly increased safety factor over stainless given the same dimensions?

In addition, it would not suffer from corrosion and it would be possible to fully bond the chainplate to the hull in a manner that could completely eliminate leaks.

What am I missing that makes it a bad idea to consider replacing my monohull's stainless chainplates with properly laid and vacuum bagged FG? I don't see any of these around on any boats as aftermarket replacements when the original stainless through-deck plates get chucked thanks to crevice corrosion.