VESSEL REVIEW | Kallista Helen – Inverlussa wellboat features innovative treatment facilities

Scottish aquaculture support company Inverlussa Marine Services recently took delivery of a new delousing boat built by local shipyard Ferguson Marine Engineering.

Kallista Helen will be operated by Inverlussa on a long-term lease with Scottish Sea Farms. Both companies had also contributed to the design work on the vessel.

The newbuild has an LOA of 26.5 metres, a beam of 12 metres, a maximum operational draught of 2.75 metres, and a maximum displacement of 558 tonnes. Designed by Macduff Ship Design, the vessel will enable Scottish Sea Farms to address the problem of sea lice, helping safeguard the health of its farmed salmon.

The vessel's key piece of delousing equipment, developed by ScaleAQ, will use water heated to between 30 and 34 degrees Celsius to kill lice, which have a low tolerance for changes in temperature.

The equipment will also include a simpler, straighter pipe layout creating a gentler experience for the fish and a wider than standard pipe of 600 millimetres diameter to ensure a smoother journey through the system. The delousing capacity has been increased to 120 tonnes per hour and 500-micron filtration is used to separate and collect the dislodged sea lice for removal from the marine environment.

The delousing equipment is housed in a dedicated shelter deck to protect it from the elements. This also frees up more space on the vessel's top deck for other equipment, including three HS.Marine cranes that will help reduce dependence on other workboats during treatments. The incorporation of cargo space and container latching points on the top deck allows for the haulage of ISO tanks should it be required.

The systems and machinery onboard have a high peak electrical load, resulting in a large engine room that spans over half the length of the hull.

Propulsion is derived from two Caterpillar C32 485kW main engines that are paired with two ZF W1800 reverse reduction gearboxes. The shafts are connected to twin fixed-pitch 1,500mm propellers housed in low-drag nozzles supplied by Kort propulsion to improve free running speed whilst maintaining a bollard pull of 15 tonnes. The vessel is also fitted with high lift rudders by Wills Ridley and a 250kW hydraulic bow thruster by Kort Propulsion to ensure the enhanced manoeuvrability required when working in and around salmon farms.

Two additional Caterpillar C32s are fitted on board as generators with a rated output of 860 kW each. These generators are used to power the thermolicing equipment, including the heating elements used to warm and maintain the temperature in the 22,000 litres of seawater contained in the fish treatment system. They also provide power for the fish pumps and a 130m³/h pump used to fill the system.

Smaller Caterpillar C4.4 auxiliary engines are also used to power the onboard systems when the main generators are not in use. The vessel also features a heat recovery system that will draw heat from the engines and transfer it to the delousing system, saving on both fuel usage and carbon emissions.

With the ability to carry over 56,000 litres of fuel and over 40,000 litres of fresh water, the vessel has the ability to stay at sea for extended periods if necessary.

Forward of the engine room below deck sit four cabins with bathroom facilities. The accommodation areas were designed to ensure maximum crew comfort and insulation from engine room noise and vibration. Each cabin is also equipped with heating, flatscreen TVs, and a working desk among other amenities.

Above these cabins, on the main deck, there is a combination galley/mess/lounge adjacent to a large dry locker. The dry locker incorporates engine room access, a shower room, access below to the cabins, and access up towards the wheelhouse. Accommodation on the fo'c'sle deck is comprised of two single man cabins with a bathroom, an AC, and electronics space as well as a dedicated control room for the thermolicing equipment.

The wheelhouse provides a commanding 360-degree view with particular emphasis over the aft deck area, thanks to the installation of floor-to-ceiling windows. From here, aft control positions have been arranged port and starboard to allow for greater operational flexibility. There is also additional crew seating, a ship's office area, and a client office workspace within the wheelhouse.

Kallista Helen is designed to operate with two five-strong crews – one from Scottish Sea Farms, the other from Inverlussa – each working three-week on/off shift patterns.

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