Required EEDI calculation Formula

Table 2: Ship type (MariEMS 2017).

Using the above concept, the following equations show the way Required EEDI is calculated for a ship. First, for each ship a “reference EEDI” is calculated using the below equation:

Reference EEDI = a*b-c . . . . . . (1)


b: Ship capacity

a and c: Constants agreed for each ship type and included in the regulation.

Reference EEDI: Reference value for EEDI.

The next step is to establish the reduction factor (X) for the ship. This is dependent on year of ship built and is specified within the regulation. Having established the Reference EEDI and X, the Required EEDI is calculated from the following equation:

Required EEDI = (1-X/100)* (Reference EEDI). . . . . . . (2)


X: Reduction rate; agreed and included in Regulation.

Required EEDI: The regulatory limit of the ship’s EEDI, which the actual EEDI must not exceed.

The Required EEDI applies only to ships named in column 1 and the ship sizes specified in column 2. For these ships, regulation 22 stipulates that Attained EEDI must always be less than or equal to Required EEDI:

Attained EEDI < Required EEDI. . . . . . (3)


Attained EEDI: The actual EEDI of the ship, as calculated by the shipyard and verified by a recognized organization.

This regulation additionally stipulates the following:

  • “If the design of a ship allows it to fall into more than one of the above ship type definitions, the required EEDI for the ship shall be the most stringent (the lowest) required EEDI”.
  • “For each ship to which this regulation applies, the installed propulsion power shall not be less than the propulsion power needed to maintain the manoeuvrability of the ship under adverse conditions as defined in the guidelines to be developed by the Organization” (MariEMS 2017).