The Environmental Protection Agency (EPA) tested the Crowley Alden A-4 Oil Skimming System at its Oil and Hazardous Simulated Environmental Test Tank (OHMSETT) facility in Leonardo, N.J. This testing was sponsored by the Naval Civil Engineering Laboratory (NCEL). The tests were required as part of a Navy purchase to assure that the product met or exceeded specifications in an RFP issued in 1985. During these tests the skimmer recovered 2 to 3 gallons per minute (gpm) (7.5 to 11.4 liters per minute (1pm) ) of oil. Ther was little or no variation in oil recovery rate introduced by altering test conditions. In calm water, the skimmer recovery efficiency was minimally 85 to 95 %. Under wave conditions, the recovery efficiency was 65 to 75 %. The test program included measurement of the maximum pump rate of an ancillary double diaphragm pump. The greatest pump rate that should be expected is 70 to 80 18pm (18 to 21gpm). Lower capacities were measured with added head, but the pump performed equally well with DFM as with water. Overall, the skimmer met or exceeded the performance characteristics required for inner harbor use. Oil skimmer, oil pollution, oil mop, OMHSETT, oil spill, oil recovery, oil spill equipment.