2 Method of calculation

 Power reduction factor P_eff due to an air lubrication system as an innovative energy efficiency technology is calculated by the following formula. The first and second terms of the right hand side represent the reduction of propulsion power by the air lubrication system and the additional power necessary for running the system, respectively. For this system, f_eff is 1.0 in EEDI formula.

______________________________________		(1)
*	In the case of PPTI(i) >0, the average weighted value of (SFCME ∙CFME ) and (SFCAE ∙ CFAE )

  2.1.1 P_eff is the effective power reduction in kW due to the air lubrication system at the 75 per cent of the rated installed power (MCR). In case that shaft generators are installed, P_eff should be calculated at the 75 per cent MCR having after deducted any installed shaft generators in accordance with paragraph 2.5 of EEDI Calculation Guidelines. P_eff should be calculated both in the fully loaded and the sea trial conditions.

  2.1.2 P_PeffAL is the reduction of propulsion power due to the air lubrication system in kW. P_PeffAL should be calculated both in the condition corresponding to the Capacity as defined in EEDI Calculation Guidelines (hereinafter referred to as "fully loaded condition") and the sea trial condition, taking the following items into account.

• .1 area of ship surface covered with air;

• .2 thickness of air layer;

• .3 reduction rate of frictional resistance due to the coverage of air layer;

• .4 change of propulsion efficiency due to the interaction with air bubbles (self propulsion factors and propeller open water characteristics); and

• .5 change of resistance due to additional device, if equipped.

  2.1.3 P_AEeffAL is additional auxiliary power in kW necessary for running the air lubrication system in the fully loaded condition. P_AEeffAL should be calculated as 75 per cent of the rated output of blowers based on the manufacturer's test report. For a system where the calculated value above is significantly different from the output used at normal operation in the fully loaded condition, the P_AEeffAL value may be estimated by an alternative method. In this case, the calculation process should be submitted to a verifier.

  2.2.1 V_ref in paragraph 2.2 of EEDI Calculation Guidelines should be calculated in the condition that the air lubrication system is OFF to avoid the double count of the effect of this system.

  2.2.2 In accordance with EEDI Calculation Guidelines, the EEDI value for ships for the air lubrication system ON should be calculated in the fully loaded condition.