In the work of Cooker & Peregrine (1991) computational results were reported for a wave breaking against a vertical wall. In the absence of the wall the wave overturns as a plunging breaker, with particle accelerations which are at most 4g, at points under the curved arch of the wave. Initially the wave is long, with small initial slope, but as time proceeds the wave steepens, until at a certain instant the water surface first achieves a tangent which is vertical. This breaking point enables us to place judiciously a vertical wall against which the wave can break. (This was achieved by computing a fluid domain which is symmetric about x = 0.) By shifting the initial position of the wave, relative to the wall, impacts of greater or less violence can be computed.