(31)In order to ensure compliance with the essential requirements, it is necessary to lay down appropriate conformity assessment procedures to be followed by the manufacturer. Those procedures should be set by reference to conformity assessment modules laid down in Decision No 768/2008/EC. Those procedures should be devised in the light of the level of the risk which may be inherent in the watercraft, engines and components. Therefore each category of conformity should be supplemented by an appropriate procedure or a choice betweens several equivalent procedures.