| 摘要 |
<p>The hull of a wind-surfer is composed of upper and lower plastics shells bonded together at a peripheral flange and contains a centreboard housing passing vertically through it. Each shell is composed of an outer layer and an inner supporting layer of plastics foam; the outer layer possesses inwardly projecting flanges at the periphery, the angle of these flanges being filled by the foam. The centreboard housing is formed of two halves, each being integral with the outer layer of one of the shells. The internal foam backing supports this centreboard housing. In addn., the non-foamed outer layers overlap at the housing and are bonded together. Pref. the outer layers are of non-foamed polyurethane and the backing layer is of rigid polyurethane foam, these two layers being joined together by cross-linking. The outer layer is pref. about 1 mm thick and the inner, foam layer 10-15 mm thick. There is no projecting flange which can cause serious injury to swimmers or other persons. The inner foam layer is firmly bonded to the outer shell and does not come away from it after a time.</p> |
