Turning the scales

by | 13th July 2021 | Ship & Boat International - News, Commercial Shipping

Home News Turning the scales


Macduff Ship Design and Ferguson Marine Engineering have completed a unique aquaculture support and salmon delousing vessel, Kallista Helen, for Scottish owner Inverlussa. The vessel, which will be chartered out to operator Scottish Sea Farms, has been hailed as the first of its kind to be designed and built in Scotland.


Although sea lice are generally non-harmful to fish in the open sea, they can become a serious problem within the confined environment of a fish farm. Unchecked, these parasites can spread rapidly throughout the farm, causing significant stress to the fish, which sometimes results in mortality. From a commercial viewpoint, lice infestation can mar the fish with lesions and expose the bone of the skull, reducing their market value. However, traditional treatment methods have their drawbacks; one approach has been to use chemicals, including hydrogen peroxide bleach, to delouse the fish. This is hardly ideal for the marine environment, especially if the bleach leaks out from the farm.


Kallista Helen has instead been installed with a Thermolicer. Designed and engineered by Norwegian firm ScaleAQ, the $US2.8 million system represents a more environmentally sound of delousing the fish. ScaleAQ explains: “A sudden rise in water temperature is a well-known method of killing lice, so the Thermolicer has been developed to bathe the fish in temperate water for a short period. This will cause the lice to die and fall off the fish, after which they are separated from the water using a 500μ filtration system and collected to be removed from the marine environment.”


The system is equipped with wide pipes and has a simple layout, so that the bathing process remains a gentle one, and ensures that fish do not become trapped or jammed against one another. The system permits Kallista Helen to delouse up to 120tonnes of fish per hour and, as the process only utilises seawater, means no chemicals are pumped into the sea. Inside her engine room, which spans over half the length of the hull, two Caterpillar C32 main engines deliver a combined 970kW. The engines are paired with ZF W1800 reverse reduction gearboxes, and the shafts are connected to twin fixed-pitched, 1,500mm-diameter propellers supplied by Kort Propulsion, to improve free running speed while maintaining a bollard pull of 15tonnes.


It’s not just the salmon that get to undergo a comfortable onboard experience. Four double cabins are located forward of the engine room, below deck, in a spot selected to ensure maximum insulation from engine room noise and vibration. Above the cabins, on the main deck, one finds an integrated galley/mess/lounge, plus a large dry locker that offers a shower area and access to the engine room, the cabins and the wheelhouse. The forecastle deck houses two single crew cabins, plus a control room for the Thermolicer equipment. The wheelhouse is spacious enough to include a ship’s office area, a client office workspace and additional seating for the crew.


(For the full article and technical particulars, see Ship & Boat International July/August 2021)


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