As container ship operators continue to seek energy savings through slow steaming, the necessary engine adjustments need to be matched by the propeller arrangement. Wärtsilä will supply fixed pitch propeller and EnergoProFin solutions to Taiwan-based Yang Ming Lines to achieve this.

The solutions will be delivered to two of Yang Ming’s container vessels, the YM Mobility and YM Milestone, and allow the speed of the vessels to be reduced from 24 to 18 knots. They are the last in a series of four Yang Ming ships to be retrofitted with the Wärtsilä fixed pitch propeller (FPP) and EnergoProFin solutions. The two earlier retrofits are said to have resulted in energy savings in the region of three to five per cent.

Post-swirl device

The newly designed Wärtsilä propeller mass is approximately 27 per cent lighter than the ships’ existing propellers. The EnergoProFin post-swirl device reduces energy losses from the flow around and behind the propeller. It is a propeller cap with fins that rotate together with the propeller. This solution provides average fuel savings of two per cent, with a payback time of less than one year, according to Wärtsilä. The propeller’s energy losses are among the factors related to the flow phenomena around and behind the propeller boss. Installing the EnergoProFin helps to reduce these energy losses and increase overall propulsion efficiency.

‘Efficiency and cost savings are extremely important in today’s operating environment, and the Wärtsilä propulsion solutions are designed to meet these needs. By enabling the engine power to be reduced, we are also enabling fuel consumption to be lowered, which in turn also leads to fewer exhaust emissions,’ says Patrick Van Gorkom, Senior Manager Sales & Sales Support, Wärtsilä Marine Power.

The Wärtsilä equipment is scheduled for delivery in March and June 2021 to the Changhong shipyard in China where the retrofitting will take place.