The effects on Required Freight Rate (RFR) of hull roughness causing loss of speed at constant power are investigated. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation and maintenance. These are utilized to determine the loss of speed. The results are then incorporated in a RFR analysis to determine the effects on vessel profitability. Examples are provided for ocean ore carriers. The effects of all roughness factors are incorporated over a vessel life ranging from 5 to 25 years. The formulations are directly applicable to other vessels for which a lifetime roughness profile is constructed and speed/power relationships have been determined. The approaches to developing the speed/power predictions and the roughness profile are provided. The analysis approach provides a means for investigating different magnitudes and scenarios of causes of roughness and their effects on RFR.

Keywords:
lifetime roughness profile, mechanical damage, roughness, hull roughness, rfr, voyage, equation, coefficient, maintenance, resistance coefficient
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2018. The Society of Naval Architects and Marine Engineers
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