Yanmar power for hybrid multi-purpose workboat

Designed and built by Fitjar, for operator Finnsnes Dykk & Anleggservice AS, the Mimmi is a working boat made to perform a variety of tasks, including pipelaying, placing sea cables and anchoring for fish farms.

”The thing that makes her unique is the power: whether that’s propulsion or the Palfinger crane capacity, we have three times the power of anything else this size. She’s the toughest service boat in Norway,” said Tommy Grønning, captain of the vessel, who was involved with the design and specification from the start.

Impressive powertrain

Propulsion comes courtesy of a 1,340kW Yanmar 6EY22AWS fitted with a selective catalytic reduction system.

The vessel is a hybrid, with a two-step Finnøy output gear with 1,000kW PTI/PTO. There is also a battery pack offering an additional 1,444kW.

“We chose Yanmar because of the service and the spare parts availability. We cannot tolerate downtime. Also, fuel economy and we wanted the SCR,” said Mr Grønning.

He added that the specification for the engine was to cope with 40 tonnes load, but this unit has a safety margin of 43 tonnes.

Mr Grønning said that the diesel engine is used to go to the worksite, then run on electrics onsite.

All the electricity on board comes via the battery package, which is not used in transit.

”It’s created a very quiet workspace, particularly at night. It’s also economical, aided by a regeneration system on the winches. This type of hybrid setup is the future,” he said.

The vessel has the capability to operate remotely down to 1,800 metres, with a seabed scanning echo sounder with 850 beams. It has a bridge installation featuring a navy multi-view and navy ROV station, with a Kongsberg HIPAP acoustic positioning system.

Before going into service, the vessel underwent the obligatory sea trials where it achieved 12 knots with a 70% load on the Yanmar. The vessel is now located at Bodø, on a pipelaying project.