This SAE Recommended Practice establishes the procedure for measuring the sound level of recreational motorboats in the vicinity of a shore bordering any recreational boating area during which time a boat is operating under conditions other than stationary mode operation. It is intended as a guide toward standard practice and is subject to change to keep pace with experience and technical advances.
SAE J1970 was originally developed for the specific purpose of measuring boat noise at the shoreline of recreational boating areas. Shoreline noise from recreational boats has now become a major public health and safety issue as a result of large "offshore-style" boats that are now being used on small inland lakes and rivers. The original version of SAE J1970 did not adequately define the applicable measurement restrictions (Section 4) and, as a result, the exact meaning of "shoreline noise" was often restricted to the point of rendering the procedure unusable in perhaps a majority of shoreline situations. This revision allows measurements to be made, for instance, at virtually any distance inland from the shoreline, thereby facilitating measurements to be performed under conditions where, for example, wave noise at the water's edge produces unacceptably high ambient noise levels thereby rendering the original version to be unusable. Subsequent modifications regarding the required vertical distance from the waterline to the microphone have been included in the revised version thereby allowing sound level measurements to be performed that are much more realistic in terms of exposure of shoreline residents to boat noise. For practical reasons some restrictions such as the one regarding "immediate" equipment calibration have been eliminated to avoid conflicts regarding a specified time limit.