SERVICE
CLASSIFICATION DEFINITIONS
Pleasure (Intermittent rating) : Limited to craft used exclusively for pleasure boating. Operation at full engine throttle should not exceed 5% of total time, with balance of usage at 90% of full throttle engine speed, or less. Maximum operation 500 hours per year.
Commercial (Continuous Rating): Boats of whatever hull form used in commercial applications, and in displacement and semi-displacement hull boats for pleasure applications (Motor cruisers, steel narrowboats, etc.) should be classed as commercial duty and the KW (BHP) rating selected accordingly.
Notes:
(i) All horsepower ratings quoted are at the engine flywheel. Due allowance must be made for transmission losses of 2½% loss on mechanical gearboxes, and 7% loss on hydraulic gearboxes.
(ii) For tropical use it is necessary to derate the engine by 3% for each 5oC above 27oC air temperature at sea level. In some parts of the world further derating for humidity is necessary in accordance with ISO.3046/1