Bespoke self-unloader for vital trade

The 25,725dwt Nukumi, launched at Chengxi Shipyard during May, has been purpose-designed to transport salt in the St Lawrence basin and Great Lakes region. Unusually for a bulker, she has been specified with a multi-engine, diesel-electric propulsion system and unique aftship hull form, conferring operational flexibility, efficiency and an elevated environmental standard for the intended trading sphere.

The project is the outcome of a strategic collaboration between Canada Steamship Lines (CSL) and Windsor Salt, arising from the requirement for a new self-unloader to sustain a domestic flow of de-icing salt. Designed in cooperation with Deltamarin, the vessel will transport rock salt, mined on one of the Madeleine Islands in the Gulf of St Lawrence, to stockpiles in Montreal, Quebec and elsewhere in the provinces of Quebec and Newfoundland.

Starting service in 2022 

Windsor Salt’s consistent delivery of de-icing salt helps keep roadways clear during the winter season across eastern Canada. Nukumi is expected to be phased into service at the start of the 2022 navigation season.

The newbuild has a fixed, single point of loading system and sole hopper, combined with handling arrangements that obviate the need for the vessel to shift during the cargo intake process, improving cargo working efficiency and safety. Self-discharge will be continuous by way of a gravity fed hold conveyor and swivelling conveyor boom on the weather deck.

As a long-term investment in regulatory-compliant and ‘sustainable’ shipping, the thorough-going technical measures implemented to reduce the ship’s impact also paid due regard to the sensitive marine environment of the Magdalen archipelago.

Manoeuvrability and plant efficiency

The power and propulsion installation is based on four Tier III-certified MaK medium-speed engine-based gensets, feeding two permanent-magnet electric propulsion motors housed in fins with feathering, controllable pitch propellers. The chosen concept offers benefits in manoeuvrability and plant efficiency, and is suited to navigation in ice-prone waters and the shallow Magdalen channel.

Furthermore, the diesel-electric propulsion train configuration makes for reduced noise and vibration, improving shipboard habitability and cutting underwater radiated noise that can be harmful to the area’s North Atlantic right whales and other sea mammals. Variable-frequency drives and a waste heat recovery system contribute to overall energy savings.

Compared to the current mainstay of the salt cargo routes, the Nukumi is expected to produce approximately 25% less greenhouse gas(GHG) emissions and 80% fewer harmful air pollutants.

With particular reference to the environmental standard achieved, the newbuild scheme has been supported by a financial contribution from Quebec’s Ministry of Transport, as part of a programme to improve efficiency in the province’s transport infrastructure.