EXPERIMENTAL-STUDY OF CONTAINMENT BOOM BEHAVIOR IN WAVES

An effort to assess containment boom performance in waves is described . New model testing instruments and procedures have been developed to provide a direct measure of boom heave response to wave excitation at several points along the boom. Measurements have been made in reproduc ible regular, irregular and breaking waves for various generic model b oom configurations over a range of wave characteristics, boom buoyancy /weight ratios and towing speeds. A model scale of 1/8 allows for test s in regular waves up to 12 ft high full scale at 12:1 length/height r atio and irregular waves with significant heights of up to 8 ft full s cale. Breaking waves equivalent to over 6 ft height above mean water l evel are also generated Measurements include total towing force and he ave motion al four locations along each boom. The results of tests of three different size models all scaled to the same 4 ft high prototype boom show no significant scale effects on heave response to the vario us types of waves. Drag differences Sound among the models are attribu table to differences in full scale lengths, as well as buoyancy/weight ratios. A buoyancy/weight ratio of 10 or greater was found to improve heave conformance with waves at optimum towing speeds of about 0.5 kn ot. Short wavelength waves, requiring the highest frequency response, are shown to be the most difficult conformance problem. Of particular concern is the fact that a catenary tow shape focuses waves near the v ertex, thereby amplifying the wave height and causing excessive motion s near the center of the boom. For this reason, light weight highly fl exible booms with maximum buoyancy/weight ratio and sufficient freeboa rd are recommended for open sea operations.