This circular is being made available for use by engine
                           manufacturers, shipowners, designers, naval architects and Administrations,
                           to provide guidance in the use of the Cost/Effectiveness Formula,
                           as set out in regulation 13.7 to MARPOL Annex VI.
                        
                        
                        
                      
                     
                     
                     
                        
                        
                         This circular will assist those identified in assessing
                           whether Approved Methods for existing engines, as described in regulation
                           13.7 of MARPOL Annex VI, could be approved.
                        
                        
                        
                      
                     
                     
                     
                        
                        
                         The values as identified in the aforementioned Formula are
                           defined as follows:
                        
                        
                        
                        
                           - 
                              
                              
                              
                                 
                                    ΔNOx:
                                       
                                    The difference
                                 between the engines designed weighted specific NOx value
                                 and the applicable limit as stated in regulation 13.7.4.
                                 
                               
- 
                              
                              
                              
                                 
                                    Power:
                                    The rated power (kW) of the
                                 engine(s) as defined on the application for an Approved Method.
                               
- 
                              
                              
                              
                                 
                                    Cost:
                                    The sale price of the components
                                 plus any installation cost above that of regular maintenance.