Seawork International, the commercial marine and workboat event of Southampton, United Kingdom in June 2014, hosted the official launch of the first Damen Twin Axe fast crew supplier 2008 (FCS 2008) with yard number 532601. During this event, the vessel, built at Damen Shipyards Den Helder, was handed over to the inaugural customer Windwave Workboats. Based in Penzance, Cornwall, United Kingdom, Windwave Workboats provides offshore wind farm support and crew transfer services to the renewable energy industry since 2008. This latest addition to their fleet is the company’s first Damen vessel.
The FCS 2008 is a smaller version of Damen’s FCS 2610 of the Twin Axe series. Since its introduction, the FCS 2610 series have been successfully deployed in the offshore wind market. It is suitable for operating further offshore in more challenging weather conditions, ensuring fast, safe and comfortable transfers to and from offshore energy parks. Whilst, in recent years, designs of these types of vessels have been pushing what can be achieved within the ’24 metre load line’ limit, Windwave Workboats and other potential clients found out that bigger is not always better. Thorough market research by the Damen’s sales and sales-support departments led to the conclusion, that for some usage scenarios in the near-shore renewable energy market, a smaller vessel with improved performance (sea keeping, speed and manoeuvrability in relation to its main particulars) would be more suitable. In response to these market demands Damen developed the FCS 2008, where ’20’ refers to the length of the vessel and ’08’ to its width, in metres.
In April 2014, Windwave Workboats came to the Netherlands to take the first FCS 2008 demonstrator for sea trials on the North Sea and their crew were immediately impressed by the capabilities of the vessel. The contract for the delivery of the first FCS 2008, which was that very same vessel, was signed soon after that, after which Damen could start customising and outfitting the vessel to this client’s requirements. As the company wanted to have night accommodation on board, a cabin with two berths was integrated in the design. The railings on the foredeck were slightly modified to provide a more spacious area to meet the client’s cargo demands. Whilst the deck itself was strengthened and fitted with container lashing points to carry two 10ft containers, additional lashing point were integrated for various other deck cargoes. The position just forward of the superstructure is intended for a container with a workshop or for storage of spare parts. The container position on aft deck is a suitable storage for transport during transit. For cargo handling purposes, a deck crane was placed on the foredeck.
Damen Shipyards Group
The Damen Shipyards Group operates more than 55 shipyards, repair yards and related companies worldwide. They employ approximately 8,000 people on all continents, delivered over 5,000 vessels since 1969 and provide almost 180 vessels annually to worldwide customers.
Damen’s focus on standardisation, modular construction and keeping vessels in stock leads to short delivery times, low ‘total cost of ownership’, high resale value, proven technology and reliable performance. Damen offers a wide range of products and extensive services, such as lifecycle maintenance services, customer finance, training and transfer of (shipbuilding) knowledge. As a result of recent additions to the Group, Damen can now also offer a network of 16 ship repair and conversion yards worldwide providing facilities for a comprehensive spectrum of conversions.
The general concept of the FCS 2008
The Damen range of FCSs consists of nine designs, each dedicated to transport of crew and materials by river, in harbours or coastal waters and further offshore. All fast crew suppliers feature the Damen Sea Axe hull form, giving the vessel pleasant sea keeping characteristics and wide-ranging operating parameters. Whereas all other Sea Axe FCSs are mono-hulls, both of the above mentioned Twin Axe FCS series are catamaran workboats ofwhich both asymmetric hulls again are based on the Sea Axe technology.
Since 2006, Damen has sold more than 120 mono-hull Sea Axes of various dimensions, mostly to offshore oil and gas companies to use for crew transfer and/or security purposes. The aluminium Twin Axe catamaran was developed between 2009 and 2010, in collaboration with the Technical University of Delft, by the same team (headed by Dr. Lex Keuning MSc) that developed the successful Axe-bow technology a few years before. Input for this design cycle was the output of a brainstorming session of a workgroup themed ‘Wind’, which evaluated this market. With the first ‘2610’ Twin Axe delivered in June 2011, to date more than 30 are sold.
Continuing on the success of the FCS 2610 and as a result of further (commercial and technical) developments in the offshore wind industry, based on feedback and changing requirements of clients, Damen recently developed the FCS 2008. As stated above the FCS 2008 is also an aluminium high-speed catamaran and features two main engines. The Axe-bowed hull shape provides the vessel with superior properties: less vertical decelerations and slamming, resulting in less potential seasickness and reduced fatigue for passengers and crew. The shape of the ‘tunnel’, under the ‘bridge’ connecting the two hulls, has been developed following that same philosophy, the aim being to create a progressively increasing hull volume proportionate to wave height. The aft positioned deckhouse of the FCS 2008 can accommodate a crew of maximum four and up to twelve passengers. This specific position of the deckhouse primarily offers two advantages: it is the most comfortable position on board of the Twin Axe and it creates a more spacious foredeck.
The Twin Axe vessels are built according to Bureau Veritas Class and can be customised to the requirements of various national authorities and specific owner’s wishes. To be able to offer short delivery times, the FCSs are to be built in series on stock at Damen’s specialised aluminium production yard in Singapore once the ‘first-in-series’ are fully developed in the Netherlands. However, since the signing of this contract four of the 2008-series vessels have been built at the Den Helder facilities of the Damen Group.
Deck lay-out and cargo arrangement
The vessel boasts a 50 square metres cargo deck, a relatively wide and stable platform which is reinforced to hold up to 1.5 metric tonne per square metre. In addition, the deck sections just aft and forward of the superstructure are both equipped for carrying one 10ft container each. The forward cargo deck features a telescopic knuckle-boom crane, a Heila HLM 5-2S, which is delivered by Double D Marine Equipment.
Six mooring bollards are installed on the main deck, two on aft deck, two amidships and two forward. On starboard side forward is the anchor equipment for handling the 105 kilogrammes high-holding-power anchor with its chain and rope.
One of the most eye-catching exterior details is the fendering. The strong, energy absorbing fendering is a combination of a rubber ‘D’-type on the sides of the hull with heavy-duty foam fenders in the bow areas. This material was carefully considered to meet the operational requirements of the FCS, which involves constantly rubbing its ‘nose’ to the columns, piles, caissons or jackets of offshore structures.
Handrails and railings are fitted to the side of the deck all the way around. They follow the staircase on centreline up onto the raised fore deck and end near the transfer or ‘landing’ area where personnel are embarking or disembarking a work site.
Wheelhouse and accommodation
Below deck, in the starboard hull, is where we find the crew’s overnight accommodation, consisting of a cabin with two ‘harbour-use-only’ berths. A storage room and one additional emergency berth is situated in the portside hull below deck. The cabin and storage area can be accessed from the accommodation on main deck level via the stairs, against the forward bulkhead.
The superstructure itself is composed of two levels: main deck and wheelhouse deck. The lower (or main deck) level on starboard side is fully dedicated to the passengers and is outfitted with twelve seats and a toilet. Port side accommodates the crew’s combined pantry and mess, a crew toilet with integrated (emergency) shower, a wet gear room and storage space.
An internal staircase leads from the mess up to the wheelhouse. The wheelhouse forward area contains the T-shaped fully integrated navigation and communication console with all required navigation, communication and ship control facilities. The helmsman’s seat, with various controls integrated in the arm rests, and navigator’s seat are on either side of the leg of the T. Starboard side aft corner is home to the chart table. All bridge equipment, navigation consoles and ‘command’ chairs were delivered and installed by Alphatron. On three sides (PS, SB and aft) of this deck is ample outside deck space, containing a 16-persons life raft on port and starboard side. This capacity can be further increased with an additional ‘spare’ raft to starboard side. The complete accommodation is environmentally controlled by means of the air-conditioning units on aft wheelhouse deck outside. The system, supplied by N.R. Koeling from Krimpen aan den IJssel, provides a total capacity of 49,000 BTUs (British Thermal Units), which is equal to 14.5 kW.
Engine room and propulsion
Besides the storage rooms and cabins, the two hulls also accommodate the engine rooms and other technical spaces. Propulsion is provided by two MTU 8V2000M72 diesel engines, rated at 720 bkW (965 BHP) at 2,250 rpm each, through a Reintjes ZWVS series (two-speed) gearbox to a fixed-pitch propeller via a propeller shaft. With this configuration the catamaran achieves a maximum speed of 25 knots and has a range of 700 nautical miles at full tank capacities. Two-speed gearboxes have been adopted to achieve to optimal engine rpm in transit mode whilst also providing pushing requirements against an offshore structure. The propellers are specially developed and delivered by Sip Marine from Drunen, whilst the propeller shaft assemblies were furnished by Bemach from Krimpen aan den IJssel, both in the Netherlands.
Two Caterpillar generator sets (one running and one stand-by) of 28.1 kVA each, which are both located in the aft of each of the engine rooms, are delivery Pon Power. The sets provide 400/230V three phase 50 Hz AC with a continuous output of 22.5 kW each. The vessel has a 24 VDC and a 230 VAC system. The 24 VDC system comprises of a dedicated battery system for engine starting, charged by the main engine alternators or by a dedicated battery charger fed by the shore power. Piet Brouwer from the Dutch town of Urk was responsible for the complete electrical installation.
The steering gear consists of two stainless steel rudders, from Damen Marine Parts in Hardinxveld-Giessendam, controlled by hydraulical rams. Two separate Sperry Marine steering systems are powered by two engine driven pumps, providing dual redundancy. The steering pumps can be electrically controlled by manual input or autopilot.
Engine room ventilation is provided by means of inlets against the aft bulkhead of the superstructure with mist eliminators on the inside. The engine room ventilation has a capacity of 6,380 cubic metres per hour for each engine room. The engine’s exhaust gas lines are typically dry-type with an injector piece at the end where exit cooling water is injected before the exhaust mixture is sprayed overboard on the inside of the hulls. Fire-fighting equipment consists of fire extinguishers in the accommodation and a fixed Novec 1230 system, delivery Ajax Chubb Varel, in engine rooms.
Customisation as a standard
Built at Damen Shipyards Den Helder, three more vessels are available from stock. The first vessel in this FCS 2008 series already outperformed expectations. With the next three vessels, Damen’s pursuit for continuously improving their products and the client’s desire for further increasing logistical possibilities on board resulted in minor modifications. Differing from the first ship, the next three will have their handrails on the fore deck all the way to the side, with only one handrail near the stairs in accordance with safety requirements. By doing so, more space is created on the raised foredeck, to place spare parts within the reach of the wind turbine’s own maintenance crane.
Another interesting option is an electrically powered aluminium rescue platform for man overboard recovery to the transom. If required this can also be retrofitted to the first vessel.
Also, research is currently being carried out to fit the Twin Axes with CPPs (controllable pitch propellers), instead of the fixed pitch propeller and the two-speed gearbox. This upgrade would provide the ideal propulsion configuration for the purposes this vessel is intended for, however it would increase the price considerably. However, Damen wishes to first complete their investigations before introducing it. Damen research teams are also focussing on developing alternatives to the standard factory fender types (for bow landing). The target here is to extend life and reduce the frequency of replacement and improving the bow landing characteristics.
The Damen approach is to provide base models that can be enhanced with a wide range of options for the client’s most specific application. Although all vessels are built to a basic configuration, no yard number is identical and all vessels are delivered as customised end products. In the near future, all Damen sales staff is going to be ‘armed’ with an app-configurator called ‘Smart Axe’ on their tablets, to provide ‘Smart Customisation’ to potential clients.