Major Overhaul of Norwegian Ferry Engine
MAN Diesel recently retrofitted the M/F Geisnes pendulum ferry’s engine to Tier II limits. This retrofit solution achieves a 30% NOx reduction. The MAN 6L23/30 main engine originally installed in M/F Geisnes was built in Frederikshavn, Denmark, in 1988 - and after the delivery of the ferry in 1989, it has served the vessel for 96,842 operating hours. In connection with the major overhaul of the main engine, it was decided by the Norwegian owner, Namsos Trafikselskab, to retrofit an upgrade package with Tier II engine components.
The Tier II main engine upgrade package for M/F GEISNES included:
• New cylinder heads with improved flow properties
• New camshaft for optimised timing
• New fuel equipment (injection pumps and injection valves)
• New gas sealing for increased compression ratio (from 12.6:1 to 13.1:1)
• Readjustment of cam drive gear wheels for retarded injection
• New pistons with improved drains and optimised piston ring configuration
• New cylinder liners with flame ring
Before and after – measurements and documentation
For engines put into service before January 2000, there are no requirements for a technical file. In this case, however, where a shipping company wants to convert and modify the engine for NOx reduction, the Norwegian authorities and the classification society DNV demand a measuring of the emission level before and after the conversion. Consequently, ISO corrected figures according to the IMO cycle E2 for propulsion plants with CP propellers are calculated. For M/F Geisnes, the emission registration and the related IMO cycle calculations were carried out in close co-operation with DNV in Oslo, who also performed the certified measurements onboard.
M/F Geisnes particulars:
Vessel type 160-ft pendulum ferry for passengers and cars
Owner Namsos Trafikselskab, Norway
Main engine MAN 6L23/30 (810 kW nominal – rated to 566 kW at 740 r/min)
Reduction gear MAN Alpha CP Propeller: MAN Alpha type VB
Classification DNV (Det Norske Veritas)