No they don't all share that issue. Those that do are invariably fiberglassed using polyester resin. Unfortunately, there is not a single polyester resin on the market that is, or ever was, formulated with sticking to, or sealing wood in mind. Boat graveyards are full of old fiberglass motorboats containing a sheet of polyester/fiberglass-covered plywood in their transoms that has delaminated, begun to rot and basically killed the boat. Back in the early days when polyester was all we had available for boatbuilding there were fairly drastic differences in the adhesive strength between different types and brands of polyester, and getting a good bond that wasn't prone to delaminating on impact was a huge issue. On the stripper boats that Norm and I built, we actually ended up sealing the bare wooden hull with a lacquer sealer before the resin was applied. The lacquer penetrated the wood better than the resin did and stuck quite well, and the polyester resin stuck better to the lacquer than it would have to bare wood. That is how we handled the delamination issue, combined with using a specific formula for a specific brand of resin (Techniglass 329-2 unwaxed polyester laminating resin which we had shipped in from Oregon) that had proven to adhere tenaciously to the lacquer-primed hull. Even so, as soon as boatbuilding epoxy resins became available, the switch was a no-brainer. As long as you can do fairly decent quality work and follow directions, delamination and water intrusion under modern epoxy/glass laminates are simply no longer an issue. The epoxy bond will exceed the grain strength of the wood - meaning that if you go to tear off the glass, it will take wood with it because the wood itself is now the weak link in the system. Epoxy resin is also the most moisture resistant sealer you can possibly find to apply to a piece of wood. In addition, boat building epoxy in the form it is used for a layup or sheathing is formulated to slightly exceed the flexibility of the wood it is adhered to. Again, the wood breaks first. So on a canoe like your re-covered Yankee, properly applied epoxy resin/fiberglass would have made the delamination and water intrusion problems you have a non-issue. Note though, that glassing over a keel is absolutely foolish and should never be done with any resin type. It's just asking for trouble, and sooner or later you are going to wear through it into raw wood and expose the keel to moisture. The typical strip builder or person recovering a rib and plank canoe using polyester resin and fiberglass did not/does not have these materials available, or sufficient knowledge of the issue. They are most likely to go buy a couple gallons of whatever polyester resin they can find, put it straight on the wood and eventually suffer from delamination and the water intrusion problems that usually come with it. Unfortunately, there are probably many times more old wooden canoes out there that were fiberglassed using the wrong resin than there are which used the right resin. It's also a rather tricky job to do properly (substantially more so than glassing a stripper) which will pretty much remove it from the realm of beginner's glassing projects. Every canoe building method has its strengths, and its drawbacks, and the epoxy/fiberglass covered wooden canoe is just another one as long as it's done well - as is the wood/canvas canoe. On an old polyester-covered boat though, the chances are that your best bet is almost always going to be removal of the old glass and re-covering the hull. Luckily, the polyester resin/fiberglass will usually come off fairly easily using a heat gun and peeling it off carefully. Why is this? It's because the bond of the polyester resin is not sufficient to consistently exceed the grain strength of the wood, which was it's problem in the first place.