Lagoon 400 Bulkhead an issue?

[44'cruisingcat]

Originally Posted by BigBeakie

The best materials testing information I could find was by the Swedish Navy which were doing meticulous panel testing for their upcoming high speed patrol boats. They tested all the core materials, e-glass vs s-glass, and the various resin formulations. They did it with both vacuum bagging wet layup and VIP.

Then they subjected the panels to various torture tests including maximum impact drop testing and repeated lower intensity cyclic loads simulating wave strikes.

The clear winner was Corecell M with epoxy resin infusion giving a 1:1 resin to glass weight ratio. The epoxy was, from memory, SP Systems which had a high "toughness" characteristic (no micro-cracking). We also tested West Systems vs SP and found the same thing.

Balsa core was down the list and had inner skin delamination, because it's compression modulus is so high. The force gets transmitted through the balsa to the inner skin, particularly where there are longitudinal members or bulkheads that restrict the panel being able to flex. So in this case, more is not better.

There is a big move in the high performance watercraft field to be using the Diab HM or Corecell M for this resistance to delamination, check it out yourself.

For a high speed patrol boat, impact resistance would be a high priority. A softer core, something like rubber would be great for impact resistance.

But on sailing cat's you're looking for structural rigidity. Stiffness.