VESSEL REVIEW | NR Rival – UK operator's new hybrid crewboat fitted with advanced fuel-saving features

UK offshore vessel operator NR Marine Services has taken delivery of NR Rival, the first in a new class of all-aluminium crewboats designed by Walker Marine Design (WMD) and built locally by Diverse Marine.

The Bureau Veritas-classed NR Rival has an LOA of 25 metres (82 feet) and can transport up to 24 technicians to and from offshore wind farms. The vessel is operated by a crew of three while the technicians are housed in an air-conditioned, fire-protected main seating cabin within a resiliently-mounted superstructure.

“The hull design is optimised for fuel saving and seakeeping in the sea condition parameters found at offshore wind farms,” NR Marine told Baird Maritime. “It is also the first crewboat in the NR fleet to have hydrofoils installed. These are fixed units on the transom and are supplied by Hullvane.”

The foils provide lift on the stern whilst underway and also dampen rolling motions, making the crewboat suitable for operation in Northern European offshore waters.

“NR Rival is the first in our fleet to feature a full hybrid system to cater for house loads, thus allowing the vessel to spend a full day at sea without the need for a generator. The batteries are then charged via shore power overnight to ensure the vessel is ready for the next day’s sailing.”

Combining fuel economy with enhanced ride comfort

The crewboat was designed by the owner under a “use less” principle in conjunction with WMD. The main design point was to develop a platform that no matter what type of fuel was used, it used less of it.

“The hull design, the electrical supply for house services using a hybrid system supplied by Brunvoll, and crew influences using VMS supplied by Heffring were selected target areas in order to achieve the desired fuel savings,” said NR Marine.

WMD designed a fine entry hull from the keel to the chine at four metres (13 feet). The hull then flares aggressively to the wet deck to provide the vessel reserve buoyancy higher up in the hull form for following sea conditions. The chine below the water line has been rounded off to provide a further 12 per cent efficiency savings.

“The foredeck has been designed to be step free when transferring from the saloon level to the foredeck. This also provides a flat foredeck for cargo/container stowage.”

Volvo’s IPS 1050 was selected as the preferred propulsion system, and NR Marine said the decision was based on the efficiencies of using a quad IPS installation. In the case of NR Rival, four Volvo Penta D13 engines that each produce 515 kW at 2,300 rpm can deliver a top speed of 33 knots, a service speed of 26 knots, and a range of 1,100 nautical miles.

Other features of the vessel include a deck cargo capacity of 20 tonnes on a deck area of 75 square metres. The deck crane selected was a TMP 900XL with a lifting capacity of 1,140 kg (2,510 lb). The TMP crane was selected for its power-to-weight ratio and simple operation for deck crews.

Application of proven design concepts

The other onboard facilities include two cabins with a total of four berths, three stores areas, two toilets with showers, a mess, a galley, and a chart table area. The comprehensive electronics suite includes a Furuno package consisting of radars, plotters, displays, GPS, AIS, a compass, an echosounder, and a navtex.

“Working in close conjunction with Diverse Marine and WMD, we were able to overcome most of the challenges during the design stage with the aid of years of experience in designing and building crewboats,” NR Marine told Baird Maritime.

“We encountered challenges in making sure the results seen in the software translated into real-time data during sea trials. Fortunately, the vessel performed over and above the software data figures with fuel savings being between 20 and 40 per cent better compared to other crewboats in the same class.”

NR Rival has already commenced operational sailings out of Lowestoft on the east coast of England. The crewboat is being utilised for personnel and cargo transfers in support of an undisclosed offshore wind farm.

"NR Rival will provide our client with a HS-OSC-compliant, 24-pax vessel with class leading performance in terms of speed, comfort and fuel economy," added NR Marine.