Warship Technology: January 2019
Recently delivered to the Royal Norwegian Navy, the logistics and support vessel HNoMS Maud is based on the ‘scalable’ Aegir design from BMT in the UK. Intended to act as a global task force support and multirole vessel and named after Queen Maud of Norway, the 26,000tonne vessel is the first of its kind in the Royal Norwegian Navy.
The fully winterised, bespoke design has a helicopter flight deck and hangar and a 48-bed hospital. In addition, it is capable of providing replenishment at sea with liquids and solids.
Designed to comply with international maritime legislation, the logistic support vessel is a bespoke double-hull design that utilises commercial off the shelf technology to ensure low through-life costs.
Ordered by the Norwegian Defence Materiel Agency, the IMO-compliant vessel was designed by BMT to the specific requirements of the Royal Norwegian Navy, offering logistical support by providing fuel and fresh water to naval vessels at sea. The first steel was cut for the vessel in 2014 and the vessel was accepted off contract in November 2018, ready to support the Norwegian fleet. On entering service, Maud became the largest ship in the Norwegian Navy.
“The most important features are the vessel’s ability to carry large amounts of solids and fuel and deliver them in open waters, to undertake helicopter operations and deliver lifesaving treatment and surgery to close to 50 patients,” said Project Manager Bjørn-Ove Stikholmen in an article in the April 2018 issue of BMT’s house magazine, Focus.
Flexibility
“Her flexibility is seen in many elements of the design, from the large container deck and ammunition-classified holds which enable her to carry different types of cargo, to the large mess decks that can be converted into hospital wards supporting the overall medical capability when required.”
Maud’s global role means all systems must remain fully operational in the most inhospitable conditions, including at temperatures as low as -30°C, which gave the BMT engineers a complex design challenge. Not only did they want to protect equipment from the elements wherever possible to minimise the risk of icing, but they also had to factor in the significant power draw required by the ship’s heating and anti-icing systems.
Creating a balanced design
“All the modifications required for winterisation have knock-on effects and we needed to understand the full impact of these from the start in order to properly balance our design,” explained Ian Savage, BMT’s Deputy Design Manager. “This involved many complex fundamental calculations and significantly advanced our learning about winterising designs.
“For example, the power required by the anti-icing systems was more than we had originally anticipated as the wind had a larger cooling effect than expected; it wasn’t just the air temperature we had to deal with. This required a detailed analysis of the operating modes to ensure that sufficient power was available for other tasks on the ship.”
Winterisation requires a host of design considerations, including locating equipment and systems internally, protecting exposed equipment, a strengthened hull, incorporating additional crew shelters and drying facilities and designing freeze-resistant tanks.
“A lot of the innovation with this vessel was around putting it all together into a balanced design; dealing with the different operational requirements for each of the varied roles that this vessel will perform, the mix of commercial and naval design standards, and constraints as one,” added Simon Jones, BMT’s Design Manager. “That challenging holistic approach, working closely with the end customer, the shipyard and other stakeholders was crucial for achieving this innovative design.”
With a length overall of 180.7m, Maud has a beam of 25.9m, design draught of 8.6m and a speed of 18knots. The ship’s primary fluid cargo capacities are for 7,000tonnes of DFM F76 and 300tonnes of AVCAT F44 aviation fuel. This is complemented by primary solid cargo capacities comprising 40 20ft equivalent unit containers/200tonnes of ammunition or a mix of vehicles and boats. The hangar is intended for maintenance of one NH90 helicopter, or stowage of one operational and one spare helicopter.
The replenishment capability takes the form of dual abeam RAS rigs and stern reel and a 25tonne SWL deck crane. The vessel also has a side ramp. The ship rigs are arranged for clear movement of cargo from the stores forward to the RAS positions and on aft for VERTREP. Almost all RAS rig equipment is below decks for protection and the RAS area and equipment is fully covered by de-icing systems.
Hospital function
The hospital was subject to a lot of design effort working with Norwegian users and experts at BMT’s specialist sub-contractor Saab Medical. The aft end of the vessel is dual role. During normal operations it is the officers and non-crew lounge and spare officers cabins. When needed the non-crew lounge converts to become a high dependency ward. All beds and equipment are stored ready behind screens in the lounge. The officers lounge and cabins become the low dependency ward.
The hospital is designed for easy flow of patients from flight deck to triage room. From there they descend by lift to the trauma, operating or CT room before moving to resuscitation and intensive care or the wards. There is also access to the lift from the main deck where there is also a de-compression chamber and access to the ship’s boats and side ramp.
The ship has also been carefully designed for her mothership role with mooring and fendering arrangements for submarines, small craft and frigates. The pilot door provides easy access and the small support cranes and main ship’s crane enable replenishment and maintenance. Connections are provided for power and fluid transfers including offloading sewage. Internally the ship has facilities for supporting boat crews including catering which can provide pre-prepared meals, a gym and sauna.
The integrated weapon system (IWS) for Maud includes a comprehensive communications system and capacity within the operations room for future expansion of systems. The ship was designed to allow for future fit of four Sea Protector guns.
Hybrid power and propulsion
A key feature of the Aegir-derived support ship family of designs is the hybrid power and propulsion system. This is a combined diesel-electric or diesel (CODLOD) system which provides for a high degree of flexibility in operation to match the wide range of modes and environments within which the ship must operate. BMT said this flexibility provides significantly lower life-cycle costs than alternative arrangements by minimising the time that the main engines and generators operate at inefficient loadings and reducing running hours of all machines.
This enables support ships based on the Aegir design to operate in a number of modes, including transit, with pure electric drive for slow speed with the generators providing ship and propulsion power; and RAS operations, the most demanding mode, in which main engines and generators are needed with the
main engines providing some power for ship’ systems.
During normal cruise mode the main engines provide all the power with electrical power provided by the hybrid machines operating as generators.
