Re: Toe rail refinish/rebed 1987 pearson
From a thread in SBO
"The hull and deck are through-bolted on an outward flange, and the resulting sandwich is then covered with a plastic rubrail. This method of attachment is strong but the outward facing flange is a bit ungainly and exposes the flange to damage in the event of a collision. The flange is topped off with an attractive oiled teak toerail."
... doesn't sound like any kind of core under the toerail, but this was a cursory look and chasing down the dozens of google hits might yield a better source...
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"