WIND FARM SUPPORT VESSELS: The Class of 26

It was only 4 years ago at Seawork International 2011 that a completely new class of offshore wind farm vessels was defined when a new vessel, 26 metres long with a 10 metres beam, was named Marineco Shamal and handed over to the owner Marineco. So began the class of 26.

As this article is being prepared the 35th vessel in this class is being prepared for delivery. In fact, so are the 33rd and 34th, all within 2 days to 2 separate owners, Severn Offshore Services from Wales taking on their first FCS2610 and SeaZip from Harlingen in Friesland taken a second pair from Damen Shipyards Group.

These FCS2610 vessels built by Damen Shipyards have set a standard for crew transfer vessels required for work on wind farms being built further away from the coast. The characteristic Axe Bows of the FCS2610 are one of the secrets of success of this vessel, reducing uncomfortable motions and improving the comfort for the 12 technician passengers who are not primarily seafarers usually. This signature bow design is used in both catamaran and many mono hull vessels built by the Dutch company.

Vessels with a large and raised foredeck area with the high bow, the two deck topside, and narrow individual hull cross section are now features being included in vessels developed by other CTV designers and built by other boat builders for the offshore wind industry.

This is not just a ‘toys for the boys’ concept.

This article looks at some of the class of 26 metres and some even larger vessels. The name of one naval architect appears frequently in this class. BMT Nigel Gee are designing crew transfer vessels that are breaking new ground over and above the previously set standard.

In the effort to reduce the overall cost of offshore wind energy it has long been recognised that restrictions placed on the industry by weather conditions limiting working weather windows, in both the construction and O&M phases of the wind farm life span, are a major factor in keeping costs high. Therefore it follows that increasing the working weather window will have the effect of lowering the overall expenditure. Any factor that enables work to continue is now being seen as an essential target to be attained.

Njord Offshore – the Njord Odin

BMT Nigel Gee have designed a vessel that is packed with these factors which enable the engineers and technicians to get to work efficiently and comfortably in weather conditions that were previously considered to be dangerous or not economically viable. Four of these vessels have been ordered by Njord Offshore, a company that has been managing 8 vessels in the 21m class for several years. These 21m vessels were also designed by BMT Nigel Gee. Offshore WIND recently spoke to Tom Mehew of Njord Offshore about the new class of 26.

Njord’s first need for a larger vessel resulted in the ordering of a Damen FCS2610, the Njord Alpha, early in 2014 which was delivered 7 weeks later from stock. Now in 2015 the first of the four vessels, the Njord Odin has been handed over to Njord Offshore in Singapore and will be arriving in Europe soon. As with the earlier 21m vessels they have been built in the Singapore yard of Strategic Marine, the Australian boat builder based in Geraldton WA, just  over 400kms north of Perth. They have other yards, not only in Singapore, but also in Vietnam and Mexico.

The CTruk range has now built 3 variants, up to 28 metres, of the first vessel, SWATH and Semi SWATH vessels, military vessels and luxury passenger vessels

The Njord Odin and the 3 sister vessels, Njord Freyr, Njord Thor and Njord Magni, are named after ancient Norse deities with plenty more of these powerful names available in case Njord should consider a further increase in the size of their fleet in the future. The vessels are 26.3 metres long (LOA) and have a beam of 9.2 metres and a draught of 1.6 metres. Careful consideration to passenger comfort has been taken, not only with the constructional design but also with the furniture and fittings. Good outside visibility from the shock absorbing passenger seats situated amidships minimises the effects of slamming in high seas and enable the wind farm technicians to keep relatively comfortable during the voyage. These features may well be outstanding in the standard of their quality, but they are all tried and tested and can be found on any number of vessels already working in the industry.

There is however innovation which appears elsewhere in the vessel. The fitting of Humphree Ride Control panels on the lower section of the stern provides for control of the vessel’s posture giving a better trim and stabilisation which increase ride comfort. The overall aim is to be able to sail in comfort when another vessel would remain in port.

There is also innovation to be found in the engine rooms. Here you will find 2 Volvo Penta engines and 2 azimuthing thrusters driving 2 sets of contra rotating propellers on each hull. They have chosen the Volvo Penta IPS 900 drive chain which gives the vessel a dynamic positioning ability to hold the vessel’s position and heading, despite the effect of the wind and currents, enabling, for example, lifting operations from or to the vessel at sea. This Volva Penta engine and drive combination has an impressive list of potentially cost reducing and environmentally friendly statistics. It offers up to a 30 percent reduction in fuel consumption with a similar reduction of CO2 emissions while at the same time providing a top speed 20 percent higher and a 40 percent increase in cruising range, all of this with a 50 percent reduction of perceived noise level.

This is not just a ‘toys for the boys’ concept, there is a very practical purpose and reasoning behind this apparent over capacity and consequential redundancy of machinery. The vessels have a designed service speed of 25 knots and a sprint speed of 28.5 knots with 4 engines, both of which are also impressive. However during the sea trials in Singapore Njord told Offshore WIND that they have logged 22 knots with one engine down and even 18 knots with 2 engines down. Both of these speeds would enable the vessel to remain on charter and be able to complete the current work phase, performing within reasonable performance and safety parameters, before having to return to port for repair work. Another example of cost reduction.

There is a cargo capability of 20 tonnes without infringing on the fuel and water capacity, and there is space sufficient for 20ft containers, with anchoring points on the after deck and fore decks. The deck is rated for maximum loading of 2.5 tonnes per  square metre, 35m2 aft and 75m2 forward of the accommodation. A 10t Palfinger Marine crane is situated near the port bow.

More innovation is apparent on the bow, with a BMT Nigel Gee patented active fender system. This includes a passively controlled shock absorbing horizontal platform which reduces impact loads by approximately 50 percent without any reduction of the vertical grip. The consequential reduction in wear and tear of the fabric of the fender also reduces cost. The vessels to be delivered later will have the option to increase the seating for the ‘passengers’ to 24 without too many extra changes in construction. The possibility for more than 12 people (passengers) has already been made available in German waters for ‘vessels which meet the criteria for High speed crafts according to the HSC-Code 2000 (which) can be surveyed and certified by the rules of the Code for Offshore Service Vessels.’ The exact wording of the code was made known by the German Government late in November 2014. With this increase in capability possible in the future the facilities on board will have to match and so the well equipped galley sleeping accommodation for 10 people and 2 w.c. and shower rooms will be ready for this change in legislation.

The remaining 3 vessels will be delivered in 2015-2016. Strategic Marine in Vietnam are currently building a further four 26m vessels for stock. The first vessels will be delivered in the summer of this year.

CTruk Semi-SWATH26

BMT Nigel Gee have also been busy working with CTruk, the company that quickly made its good reputation with just one product in 2010, a 16.5m vessel with a tough composite structured catamaran. The CTruk range has now built 3 variants, up to 28 metres, of the first vessel, SWATH and Semi SWATH vessels, military vessels and luxury passenger vessels.

It is the CTruk 26.3m Semi SWATH vessel designed in collaboration with BMT Nigel Gee that is the latest news from their current building facilities in Brightlingsea, Essex.

Semi SWATH design combines the hull features of both Catamaran and SWATH vessels, a combination that results in a reduction in bow-diving while maintaining good seakeeping capabilities.

The SWATH (Small Waterplane Area Twin Hull) technology will enable the vessel to sail in harsher sea conditions while maintaining a stable and steady platform for the engineers and technicians going to work in the morning and returning as they are writing their day reports or just relaxing after a long, hard day at the turbine. The tried and tested Semi SWATH design combines the hull features of both Catamaran and SWATH vessels, a combination that results in a reduction in bow-diving while maintaining good seakeeping capabilities. The vessel is similar in design to the well proven 28m Cymyran Bay operated by Turbine Transfers and designed by BMT in 2011.

This vessel is designed to be fitted with a MTU 12V engine in each hull driving MJP water jets which, with the benefit of the light composite hull material, will give it a service speed of 25 knots and a maximum speed of 29 knots.

The 12 passenger configuration housed in the topside that is much wider than CTruk’s previous vessels provides ample space for the chairs, tables and space for personal equipment. In addition to this arrangement CTruk’s patented reconfigurable deck area has two completely new topside variations that make good use of the greater dimensions of this vessel.

For hydrographic survey work there is a topside configuration with 8 single berth cabins, each with a w.c. and shower compartments, a galley and mess room on the lower deck. The upper deck houses the working area with equipment which is sited directly behind the wheel house. A moon pool can be situated between the two hulls aft of the accommodation.

The second new configuration is for 60 people seated in the passenger lounge which is approximately 7.5m x 7.5m. There are two columns of 8 twinned chairs on each of the outer sides of the lounge and 2 columns of 7 twinned chairs inside this spacious lounge. In this configuration the vessel is ideal for complete crew transfers to, possibly, an offshore support vessel such as the Ulstein SX175 O&M vessel working with WINDEA Offshore for Siemens. Crew transfers of the wind engineers and technicians with this vessel completing the round trip within a reasonable time frame will allow the SX175 to continue working offshore without having to make the round trip to port.

As previously stated, any factor that enables work to continue is important part of reducing costs in this industry.

Piriou WFSV 26w

The French shipyard Piriou, based in Concarneau, about 90 kilometres South West of Brest in Bretagne, France, announced in mid December the sale of the first vessel in their WFSV 26w class to Opus Marine GmbH. Later, early in March this year, just before the EWEA OFFSHORE exhibition in Copenhagen, they announced the sale of the second vessel in this class which is to be managed by Windcrew Workboats and join three other vessels Ocean Wind 4, 5 and 6 as Ocean Wind 8 of Hartlepool. These vessels were built by the South East Asia Shipyard (SEAS) in Vietnam which is owned by Piriou. They also fit into the ‘class of 26′ designed by BMT Nigel Gee as project NG909.

Opus Marine GmbH in Hamburg work closely with Turbine Transfer, the crew transfer vessel company based in Holyhead, Wales that has long recognised that larger vessels will be needed for the future.

The Opus vessel, Largo, will join their fleet of 4 other vessels when it is delivered in Europe as this article is being written, along with the vessel to be managed by Windcrew Workboats, after being shipped from Vietnam.

Both these vessels are propelled by Hamilton Water Jet Propulsion powered by 2 MAN engines, type D2842 LE463 engines which give the vessel a top speed of more than 28 knots. They have anchoring points for two 10’ containers on the fore deck and one on the after deck. For survey work the Opus vessel has been fitted with an A-frame at the aft end of the vessel, otherwise the two vessels have very few differences.

Along with Njord Offshore and the companies that will be looking at the new CTruk 26.3m Semi SWATH, both of the companies, one in Germany and the other in England, have recognised that the future offshore wind farms being built further away from the coast will require vessels offering a higher level of seakeeping properties with greater comfort and lower noise levels and less vibration for the ‘passengers’. On the other hand the charterers will need to have a greater cargo capacity and less down time caused by weather or mechanical failure. Looking at the deliveries and orders for the FCS2610 and the vessels designed by BMT Nigel Gee, and built by these different yards, it would appear that the parties involved are meeting the challenges presented by the new generation wind farms and that the vessels are fit for purpose in this new harsher environment.

Dick Hill