Offshore Breakwaters

The determination of height and pattern for waves that are diffracted by an infinitely long breakwater, or by a breakwater gap, has been based on the theoretical solution for optical diffraction. Correct results are obtainable at distances in the shadow zone many wave lengths from the breakwater, but within an area of three wave lengths the results are in error. Offshore breakwaters of limited length, although basically the same as the infinitely long breakwater, have peculiarities that must be studied if their operation, in preventing beach erosion for example, is to be successful. The main factor to be considered is the wave pattern close to the breakwater. Model tests for wave patterns with two different lengths of breakwater and waves of different steepnesses are described. Results are presented in a form suitable for application.