The problem of waves passing through a gap in an infinitely long breakwater is reduced to the solution of a Fredholm integral equation of the first kind. Wave amplitudes across the gap are shown to exactly equal incident wave amplitudes, but wave amplitudes throughout the remainder of the flow must be calculated numerically. Solution accuracy is easily checked by comparing solutions for several different boundary node spacings, and it is suggested that this method appears to give results that are easier to calculate and are more accurate than previously calculated solutions.