by GreenLake » Sun Feb 16, 2014 1:31 am
Sean, a stringer is a narrow, strip-like reinforcement that usually goes fore-and-aft. "Core" the way it's used here refers to the middle layer in sandwich construction of panels. The sandwich construction doesn't have to go the width of the hull.
In terms of mechanics, the stringer acts like a beam, the cored sandwich acts like a plate. These have somewhat different characteristics.
For stringers, especially if very narrow, the sides can be constructed in a way that allows the stringer to be hollow and yet function as designed. In which case any core material is icing on the cake. The wider the stringer gets, the more support it would need in the middle. In principle, if you desperately wanted hollow stringers you could place two narrow profiles side by side.
Having wet balsa in a stringer is still going to add weight to your boat (and it could freeze if you store your boat outside in a place where frost occurs). Any failure of the balsa might well be less of a total failure, because the sides can carry at least part of the load. Still, Mike's analysis holds.
The good news is that redoing your stringers is a limited project (after all, they are rather limited in extent).
~ green ~ lake ~ ~