This part of ISO 14509 specifies the conditions for obtaining reproducible and comparable measurement results of the maximum sound pressure level of airborne sound generated during the passage of powered recreational craft of up to 24 m length of hull, including inboards, stern drives, personal watercraft (PWC) and outboard motors. It also specifies standard craft based type tests for stern drives with integral exhaust systems and for outboard motors. It also specifies the procedure to be followed if, in addition to the máximum sound pressure level, the determination of the sound exposure level is desired. NOTE For craft other than those specified above, ISO 2922 is applicable for sound emission measurements. The accuracy grade of the acoustical test procedures specified in this part of ISO 14509 is engineering grade (grade 2)