VESSEL REVIEW | Fosna Neptune – Dive and ROV support boat for operation at Norwegian fish farms

Norwegian aquaculture support specialist the Abyss Group (formerly Abyss Aqua) has taken delivery of a new fish farm service boat built by local company Skarsvåg Boats.

Fosna Neptune was built to be capable of general fish farm support, particularly providing support for divers and remotely operated vehicles (ROVs).

“The vessel is a purpose-built diving vessel designed to ensure efficient operations and a comfortable working environment,” Skarsvåg Boats told Baird Maritime. “At 18 metres (59 feet) long and 5.4 metres (18 feet) wide, she makes highly efficient use of the available space and includes a dedicated dive room, a control room, a wheelhouse, a mess, four cabins, and a bathroom.”

“What makes the vessel particularly interesting is the level of functionality incorporated within a relatively compact footprint. Every area has been designed around the operational needs of the dive team, creating an efficient workflow between the dive room, control room and aft working deck. The vessel also represents the largest and most complex project undertaken by Skarsvåg Boats to date.”

Outfitted for secondary roles including survey, maintenance and construction support

The builder said the brief called for the creation of a purpose-designed diving vessel tailored to the owner's operational needs. The vessel had to provide efficient support for diving operations while offering a comfortable and practical working environment for the crew.

“Maximising functionality within a compact footprint was a key objective, resulting in a layout that includes dedicated diving facilities, accommodation, control spaces, and modern onboard amenities.”

The boat’s typical duties include underwater inspections, maintenance work, subsea construction support, survey operations, and ROV deployments. The vessel was built to provide a safe and efficient platform for divers and support personnel while serving a wide range of commercial and industrial marine projects.

“The vessel provides the owner with a dedicated, purpose-built diving platform capable of supporting a broad range of subsea operations,” said Skarsvåg Boats. “By combining diving facilities, accommodation, control spaces and operational equipment in a single vessel, it improves efficiency, safety and comfort compared with using adapted workboats that were not originally designed for diving operations.”

Proven diesel propulsion setup guaranteeing reliability

The propulsion arrangement includes two Volvo Penta D13 diesel inboard engines, a John Deere 20kVA generator, and a 20kWh lithium battery bank that will supply electrical power for the various onboard systems when the vessel is stationary and the engines and generator are not in use. The engines are fitted with exhaust gas cleaning systems.

“The propulsion package provides a combination of reliability, fuel efficiency and excellent manoeuvrability, making the vessel well suited for both transit operations and precise positioning during diving missions,” Skarsvåg Boats told Baird Maritime. “The propulsion system is complemented by a bow thruster to enhance low-speed control and station-keeping capability.”

The builder explained that the propulsion system was selected with a strong focus on operational reliability and ease of maintenance. In particular, the combination of twin engines, conventional shaft drives, and a bow thruster offers a robust and proven solution that can be serviced worldwide while providing precise manoeuvring capability during demanding diving operations.

Deck and interior layout ensuring greater operating efficiency

The wheelhouse electronics include a Raymarine navigation suite consisting of: dual Axiom 2 XL24 displays for the skipper, dual Axiom 12 displays for the co-pilot and dual Axiom 7 displays at the helm; a Cyclone open-array radar; a CP100 echosounder; an AIS4000 AIS; and Navionics charts.

A Teledyne FLIR M232 thermal imaging camera and engine room/deck surveillance cameras are also fitted. The wheelhouse meanwhile features a dedicated control room from which the crew can monitor dive and ROV activities.

There is a dedicated room for two divers with an adjacent control room, a custom dive ladder and dive mast on aft deck, a bottle bank, a compressor installation, a freshwater wash-down point, and an IP55 monitor cabinet.

“The aft deck has been specifically designed around diving operations, with a dedicated dive mast, a custom diving ladder and direct access to the dive room and control room,” said Skarsvåg Boats. “This creates an efficient workflow for divers and support personnel while maximising safety during launch and recovery operations. The vessel is also prepared for integration of specialist diving and ROV equipment, allowing it to be adapted to a wide variety of mission profiles.”

The interiors are kept comfortable with the aid of HVAC.

For Skarsvåg Boats, one of the main design challenges was fitting all the required functionality into a relatively compact 18-metre platform without compromising comfort, safety or operational efficiency.

“The vessel needed dedicated diving facilities, accommodation for crew, technical spaces and modern equipment while maintaining good stability, weight distribution and seakeeping characteristics,” the builder told Baird Maritime. “Achieving an efficient layout that supported diving operations and day-to-day usability was therefore a key focus throughout the design process.”

With regard to construction, since the vessel was the largest Skarsvåg Boats has built to date, the project introduced new technical requirements, stricter regulations, and a greater level of complexity compared to the company’s previous builds.

“This required us to develop new solutions, adapt our processes, and gain experience in areas that had not previously been part of our portfolio. Despite these challenges, the project was successfully completed and has provided valuable knowledge and experience for future vessels of similar size and complexity.”

In particular, the work on Fosna Neptune gave Skarsvåg Boats valuable experience in building larger and more complex vessels.

“We refined our processes for project planning, system integration, regulatory compliance, and documentation, all of which will benefit future builds. The project has strengthened our confidence and capability to deliver vessels of similar size and complexity in the future.”