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post #6 of Old 05-25-2006
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The two snippets that you referred to have no reference to coring at all. Coring is an entirely separate issue.

Properly done, a cored hull should have a much longer life than a non-cored hull. Fiberglass is a very fatique prone material, meaning over time, the more it flexes the weaker it gets. Coring produces a much stiffer hull than can be practically achieved without coring and therefore a cored hull is less prone to fatique. A coring with 'memory' can withstand enormous impacts without damage, permanent distortion or delamination. Coring with memory helps to absorb and distribute shock loads into a larger panel area thereby reducing the localized unit stresses.

Most manufacturers of boats without cores laminate a heavier panel than the outer laminate of a cored hull in an attempt to equal the stiffness of a cored panel. To keep laminating costs down, this is generally done with lower cost resins and lower tech laminates, and substantial qualitites of non-directional laminate (mat). Non-directional laminates are much more prone to fatigue and have been shown to greatly reduce impact resistance especially over time. From an engineering standpoint, and durability standpoint this is a very inferior way to build a boat.

Which is not to say that all cored hulls represent the best construction technique. We have all encountered boats with delaminated coring and to a great extent that is what gives coring its bad reputation. BUT, coring varies widely in quality and workmanship has to held to a higher level when a hull is cored. Early coring techniques were not very good and so to one degree to another core failure is pretty common in older boats. Similarly the power boat industry has been using poor quality low density foams, with minimal skins for years leading to the kinds of dramatic failures that David Pascoe tends to focus on.
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