VESSEL REVIEW | Wim Wolff – Coastal and mudflat research boat delivered to Dutch science institute

The Royal Netherlands Institute for Sea Research (Nederlands Instituut voor Zeeonderzoek; NIOZ) recently welcomed a new coastal research vessel into service. The vessel has been named Wim Wolff after a Dutch ecologist who specialised in mudflat research. Aarnoud van de Burgt, the head of NIOZ's National Marine Facilities Department, said the vessel is capable of both running dry on mudflats and sailing up to 20 nautical miles offshore.

Built for demanding use in shallow-water areas

Wim Wolff was built by Thecla Bodewes Shipyards to a design by Dutch naval architecture firm Conoship International. The vessel will be operated primarily in the North Sea, the Wadden Sea, and the Southwest Delta region into which the Rhine, Meuse and Scheldt rivers flow. It will replace Navicula, the NIOZ's earlier and slightly smaller shallow-water research boat that has been in service for nearly 40 years.

"The new vessel enables the marine science community in the Netherlands to have a comfortable, innovative and sustainable vessel for research in the Wadden Sea, the Southwest Delta, and the North Sea," Thecla Bodewes told Baird Maritime. "Also, coastal trends that are now emerging are likely to continue over the lifespan of the vessel. For instance, the water is getting warmer, sea level rise is accelerating and due to severe droughts and more extreme rainfall, there is greater variation in freshwater inflows to the sea, affecting entire coastal ecosystems and their usage. Because of the great spatial diversity in climate trends and cumulative effects of human activities in coastal areas, the versatile Wim Wolff is an essential platform for researchers to regularly monitor the changing conditions of the coast."

The builder added that the vessel will be used for ultra-shallow water marine research, with some research activities taking place in the tidal inlets and in the coastal zone of the Dutch North Sea. Surveys in the coastal zone, which are flexible in terms of implementation, are to be planned when weather conditions permit. Duties will include sampling of soil areas as well as research related to birds, fish, and shellfish.

"The vessel will be able to pass through the tides between the various basins in the Wadden Sea around high tide," added Thecla Bodewes. "The draught should therefore be a maximum of one metre at full load and 0.9 metres at partial load. A shallow draught is also of the utmost importance for easy access to certain parts of the Wadden Sea and the Delta."

For navigation at sea, the vessel can be ballasted to a draught of 1.2 metres, which will improve its seagoing characteristics. However, running aground will be a regular occurrence, and the vessel's hull is suitable for it.

"The hull bottom will be strong enough and flat enough to allow routine dry-ups at low tide. In addition, the hull shape ensures that the propellers and the rudders are fully protected from potential damage from underwater obstacles. The vessel must also be able to work as a tug or pusher boat for small objects."

"Ensuring the maximum draught of one metre was one of the biggest challenges we encountered," the builder remarked. "The calculated displacement of the completed vessel and the longitudinal centre of gravity location proved to be major issues. Also, the weeding out of space in the vessel, especially in the technical spaces, was a very complex process."

The port and starboard sides meanwhile permit the installation of a measuring pole used for lowering acoustic measuring equipment into the water. The pole can be retrieved to exchange measuring equipment. On board, there is room for installation of a data network connection, which will be determined in consultation with the NIOZ.

Low-emission propulsion ideal for sensitive marine areas

Wim Wolff has an LOA of 36.95 metres (121.2 feet), a moulded beam of 10 metres (33 feet), a design draught of one metre (3.2 feet), a moulded depth of 3.43 metres (11.3 feet), a deadweight tonnage of 74, a gross tonnage of 420, and space for four crewmembers and up to 12 researchers/technicians.

The propulsion system includes a 348kWh lithium-ion battery pack, two 250kW thrusters, a 100kW bow thruster, two 300kW permanent magnet motors, two main generators, and a harbour generator. The generators can run on diesel or hydrotreated vegetable oil (HVO), though these may be modified in the future to operate on either hydrogen or methanol. The main generators operate on both on 1,500 and 1,800 rpm, automatically switching over depending on power demand, and these can be used to charge the batteries as an alternative to the onboard shore power connection.

"The propulsion needed to be reliable, efficient, and capable of dynamic positioning," Thecla Bodewes told Baird Maritime. "The exhaust systems were configured to be quiet, and the vessel will even allow future retrofits wherein the existing generators will be replaced with emission-neutral alternatives."

The electronics setup is divided into a propulsion switchboard and a hotel switchboard. The propulsion net is split into an AC and DC rail, and the DC rail is connected to the generators. The DC rail is connected to the battery pack to allow the DC power to be added to the AC rail at any time. A power management system determines and regulates when battery DC power will be supplied to the AC rail.

Ample research facilities and deck equipment

The builder added that the vessel will also be available as a "living laboratory" for the Dutch maritime sector. Systems and installations should be suitable for easy onboard installation and testing of innovations from that sector, including in certain cases of integration into existing systems.

Onboard facilities include wet and dry laboratories (with equipment for continuous analysis of water quality even while the vessel is underway), berths, and a working deck with a total area of 125 square metres (1,350 square feet) for transporting either two 20-foot containers, four 10-foot containers, or an equivalent total volume.

Equipment on the working deck includes a 1.5-tonne deck crane and a five-tonne hydraulically operated A-frame. The A-frame allows acoustic measuring equipment to be lowered past the waterline and to be retrieved as quickly as possible, such as when a different piece of equipment needs to be used at the same site.

The deck equipment is hydraulically driven from a hydraulic power unit (HPU) in the steering gear room, though a remote control box can also be used to operate the equipment. The forces on the deck equipment are calculated with Dynamic Application Factor (DAF) of 2 for work under water.

Wim Wolff was designed to have an operational service life of more than 30 years, even taking into account regular use under the harsh conditions associated with shallow waters with high contents of sand and rock. Thecla Bodewes thus developed a modular energy concept with a propulsion train independent of the energy source system. This enables the use of alternative energy systems without the need for major conversion work. It also helps the vessel avoid the risk of its powerplant being outdated due to the introduction of a growing number of cleaner marine fuels in the future.

"The materials used in the vessel's construction are recyclable and were manufactured in an environment-friendly manner," Thecla Bodewes told Baird Maritime. "Also, since the vessel is relatively small but has an extensive building specification, we learned it becomes necessary to perform a thorough design check to ensure a successful construction and outfitting."