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That does not tell you a whole lot about the hull lay-up except that the hull does not have chopped glass. Fiberglass can be laid up in a variety of fabrics (E and S glass, woven roving, mat, cloth, bi- and Tri axial etc) and a variety of resins and orientation patterns. (Phallo 153: the layups are rarely crossed at 90 degrees but were rotated at specific angles intended to trace stress patterns and reduce bias stretch). The Islander brochure tells you almost nothing about the lay-up itself other than it was done by hand.
The one phrase that does catch my attention is "alternate Plys". I am speculating that this refers to alternating between plies of mat and woven roving, a very typical 1960's and 1970's layup schedule. Woven roving was a course fabric that was hard to laminate to itself and so the mat was added to bridge between the layers of roving. We now know that non-directional fabrics like Mat (especially as used in the resin rich, bulky layups of the 1960's and 1970's) greatly reduces the impact resistance of the laminate and also greatly reduces the resistance to fatigue over time.
As to the deck, plywood coring (except at high stress areas such as hardware fastening) makes a very poor choice for a core material in that it is prone to rot and unlike balsa spreads the rot in all directions resulting in a more rapid spread of the core rot. In most, but not all cases, plywood was chosen as a less expensive core material.
Jeff
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