With constant use over time, the low shear strength of foam core fiberglass stringers becomes evident. The foam begins to split and break down, allowing the glass skin to flex independently. The eventual result is hull failure. A wood stringer system maintains its strength without flexing. In order to achieve adequate strength in a fiberglass stringer system without injecting a core, it would be too heavy and expensive to produce. Mass (thickness) is the only way to provide strength in fiberglass stringers and unless a core (foam) is injected into the glass stringer system, there simply is not adequate strength. All the best manufacturers of small fiberglass boats agree that properly constructed boats begin with marine grade plywood stringers which are encapsulated and hand rolled in fiberglass and resin. Parker's solid fir plywood stringer system continues to give customers the strongest, toughest and safest fiberglass boats built. When boats are built properly, there is no need for gimmicks.
