One of the most common sources of failure in the application of floating oil booms to contain an oil spill is leakage between the end of the boom and the adjacent shoreline, deck or bulkhead. Booms cannot be fastened solidly to the shore since they must rise and fall with the changes in height due to tides and waves. The use of counter-currents generated by a fire stream or prop wash is attractive, although it ties up a boat often needed for other tasks. Futhermore, the shallow draft of a small boat allows oil to escape beneath the boat unless the boat is overlapped by the boom. Securing boom to the boat while avoiding the fouling of the boat's propeller then becomes operational concerns. A simple structure is described for mounting a small outboard motor to 'seal' the gap. This boom terminator can be constructed on-scene with tools and materials generally available around the waterfront by relatively unskilled personnel.