The performance of high speed, underwater vehicles is limited by flow noise. Turbulent flow over the vehicle shell causes an output from an array which is mounted to it. Arrays which are located under the boundary layer are affected by high wave number components and must be separated from the turbulence by a coating. Arrays which are located in the laminar region are still affected by the turbulent flow but in this case the energy is transported through the structure. The paper discusses the mechanisms involved and shows techniques which can be used to mitigate the problem. Some results are shown indicating the amount of reduction that has been achieved with some of the approaches.