2 Method of calculation
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Statutory Documents - IMO Publications and Documents - Circulars - Marine Environment Protection Committee - MEPC.1/Circular.796 – Interim Guidelines for the Calculation of the Coefficient fW for Decrease in Ship Speed in a Representative Sea Condition for Trial Use – (12 October 2012) - Annex – Interim Guidelines for the Calculation of the Coefficient fW for Decrease in Ship Speed in a Representative Sea Condition for Trial Use - Part 2: Guidelines for Calculating the Coefficient FW from the Standard FW Curves - 2 Method of calculation

2 Method of calculation

  2.1 Three kinds of standard fw curves are provided for bulk carriers, tankers and containerships, and expressed as a function of Capacity defined in the 2012 Guidelines on the method of calculation of the attained Energy Efficiency Design Index for new ships (EEDI), adopted by MEPC.212(63). Ship types are defined in regulation 2 in Annex VI to the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto, as amended by resolution MEPC.203(62).

  2.2 Each standard fw curve has been obtained on the basis of data of actual speed reduction of existing ships under the representative sea condition in accordance with procedure for deriving standard fw curves. (see appendix 2.)

  2.3 Each standard fw curve is shown from figure 1 to figure 3, and the standard fw value is expressed as follows:

standard fw value = a x ln(Capacity)+ b
  • where a and b are the parameters given in table 1.

Table 1 Parameters for determination of standard fw value

Ship type a b
Bulk carrier 0.0429 0.294
Tanker 0.0238 0.526
Containership 0.0208 0.633

Figure 1 Standard fw curve for bulk carrier

Figure 2 Standard fw curve for tanker

Figure 3 Standard fw curve for containership

Parent topic: Part 2: Guidelines for Calculating the Coefficient F W from the Standard F W Curves
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