The primary purpose of speed and power trials is to determine a ship's performance in terms of ship's speed, power and propeller shaft speed under prescribed ship's conditions and thereby verify the satisfactory attainment of a ship's speed stipulated by EEDI regulations and/or contract.
ISO 15016:2015 defines and specifies the following procedures to be applied in the preparation, execution, analysis and reporting of speed trials for ships, with reference to the effects which may have an influence upon the speed, power and propeller shaft speed relationship:
the responsibility of each party involved,
the trial preparations,
the ship's condition,
the limiting weather and sea conditions,
the trial procedure,
the execution of the trial,
the measurements required,
the data acquisition and recording,
the procedures for the evaluation and correction,
the processing of the results.
The contracted ship's speed and the ship's speed for EEDI are determined for stipulated conditions and at specific draughts (contract draught and/or EEDI draught). For EEDI, the environmental conditions are: no wind, no waves, no current and deep water of 15C.
Normally, such stipulated conditions are unlikely to be experienced in part or in full during the actual trials. In practice, certain corrections for the environmental conditions such as water depth, surface wind, waves, current and deviating ship draught, have to be considered. For this purpose, during the speed and power trials, not only are shaft power and ship's speed measured, but also relevant ship data and environmental conditions.
The applicability of ISO 15016:2015 is limited to ships of the displacement type.