VESSEL REVIEW | Geraldine Mary – Hybrid vessel for Scottish aquaculture support company

Inverlussa Marine Services of Scotland recently took delivery of a new custom-built workboat from a local shipyard. Designed by naval architecture firm Macduff Ship Design, Geraldine Mary is named after the mother of Inverlussa Director Douglas Wilson. The name has been re-used following the sale of the original Geraldine Mary to another local aquaculture company in early 2020.

The workboat will be operated on long-term charter with Scottish Sea Farms. It will be used primarily to inspect and service larger pens and nets at the charterer's marine farms around Scotland's west coast.

Inverlussa said the vessel was built to the company's exact specification based on years of experience of vessel design and operation with particular detail placed on deck equipment, layout, and protection to ensure more efficient working areas.

The workboat has a length of 21 metres, a beam of 8.35 metres, a maximum draught of 2.3 metres, accommodations for two full-time crew plus two additional personnel, a forward deck that can transport one 10-foot and two 20-foot containers or up to 90 tonnes of cargo, and 72-tonne and 13-tonne deck cranes. The 72-tonne forward deck crane is fitted to enable the vessel to handle Scottish Sea Farms' new 120-metre and 160-metre pens.

A dry hold with capacity for 30 cubic metres is also fitted.

A hybrid propulsion setup includes two Doosan 4L126TI 335kW main engines driving fixed-pitch propellers, a battery pack, and 120kW and 20kW harbour generators. The engines can deliver a bollard pull of eight tonnes and speeds of between eight and 11 knots.

The battery pack will meanwhile enable the vessel to use its harbour generators more efficiently. This will allow the generators to be shut down overnight or between operations during the day to save on fuel as well as reduce emissions of CO2 noise that could otherwise adversely affect fish health and water quality at the pens that are being serviced. Inverlussa Managing Director Ben Wilson said the decision to introduce a semi-hybrid power system aboard the new workboat was deemed as a cost-effective, time-efficient amendment of an existing design compared with going fully hybrid with a complete redesign.

The crew accommodations include two single cabins, one double cabin, a mess with galley, a shower, and a changing/drying area with toilet.

Geraldine Mary is a sister vessel to Helen Rice, which Scottish Sea Farms has operated under contract from Inverlussa for the past two years. The key improvements on the newer workboat include a larger forward crane, a larger deck winch, and an additional cabin in the accommodation spaces.

Geraldine Mary was designed to MCA Cat 2 rules, indicating safe operation up to 60 nautical miles offshore.

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