hmm... the way I see it.. you can always add more fiberglass to reinforce any area that seems to be getting weak. how many of the 100 year old + boats have all thier original planks? I've abused my boat for the last 5 years.. she hasn't had bottom paint in 10 years, she's 1/2" thick at her tops and over one inch at her keel, she shows no blisters, and she still won't flex. granted she was build in a garage in 1971 by a man and his son, she's a good example of how long they can last unattended. she's been neglected as I've been sailing my catalina 27 all over the pacific. I've put over 90,000 miles on my catalina in the past 8 years and just lost her last week in the worst storm southern california has seen in 2 years.. as to why I was out in a storm... santa barbara harbor denied me safe harbor due to lack of funds since I had just lost my wallet and all my money.
let's see how many of the newer thin layup boats are still going strong in 30 or 40 years... I'll bet my thick frp boat is still going... I hope she is anyhow.