Mayflower stretches her sea legs

Some 400 years after its namesake took the pilgrims to New England, the Mayflower Resolution sets sail from the south of England having undergone its final stages of completion before entering service .

The Mayflower Resolution berthed at the Duchy Wharf in Falmouth Harbour, UK at 22:30 hours on Tuesday 10th February 2004 after completing an 11,000 nautical mile voyage from the build yard in China.

The Mayflower Resolution is a specialised vessel designed by Knud E Hansen in Denmark to install wind turbines offshore ? a significant development for the renewable energy sector. The design brief was to design a vessel that will limit the risks associated with working in the North Sea by giving the vessel high manoeuvrability, a high speed jacking capability and a dynamic positioning capability.

The 130.5m long, 38m wide vessel is able to work in less than 3m of water and once located, uses its six legs to jack itself up to form a stable platform capable of working in depths up to 35m. A 300-tonne crane is used to install the turbine components and the ship can carry parts for up to ten large turbines eliminating the need to

constantly return to base.

Mayflower Resolution is equipped with a diesel-electric system powering four azimuthing thrusters and three tunnel thrusters. It was built by Shanhaiguan shipyard in China for Mayflower Energy, a subsidiary of renewable energy company The Mayflower Corporation, and was originally known as the TIV-1.

The vessel?s jack-up system was tested in Falmouth with the assistance of the A&P yard, which also carried out some repair work. David Daniels, A&P Falmouth?s commercial director told The Motor Ship: “Basically our job [in addition to assisting with testing the jack-up system] was to fit new replacement bow thrusters, a replacement engine generator and some other minor works.”

The vessel is equipped with three tunnel thrusters, which can be controlled manually from the forward bridge console, from the bridge wing consoles by joystick via the DP (dynamic positioning) system and from the portable independent joystick. In DP mode they are controlled by the DP

system.

Power is supplied from two sets of two main generators and one harbour generator located in two engine rooms, port and starboard. One emergency generator is located in a separate room in leg No.2. Power distribution is via two switchboard rooms, port and starboard. Main power is 690 VAC, which is transformed to 440, and 220 VAC for auxiliary machinery and small power consumers.

Testing

The switchboard rooms can operate independently or in parallel and power to the jacking system can be supplied from either MSB. A power management system is fitted in both MSB?s, which will start and stop engines as power demand requires.

Although the yard was not directly involved in the testing of the jack-up platform, Daniels explains: “We did help out where they obviously needed yard assistance, but in the main this was generally done by Mayflower and their experts.”

The vessel employs a cylinder type jacking

system.

Each leg has four primary and four secondary cylinders ?the secondary cylinders hold the vessel while the primaries recycle at the end of each stroke. Automatic jacking is achieved by the combination of the primary and secondary cylinders. The vessel is retained in position by catch beams, which are housed in catch beam rings encircling each leg and attached to the jacking cylinders.

The system elevating capacity is 2,500T per leg and holding capacity is 5,000T per leg. There are two jetting pumps for freeing the spud cans from the seabed. Water is pumped underneath the spudcan to break the vacuum holding the leg if vessel buoyancy is insufficient to free the leg.

After transiting to the Port of Mostyn in Wales for loading, Mayflower Resolution proceeded to the North Hoyle offshore wind farm site off the coast of North Wales to complete the installation of the final Vestas V80 – 2 MW wind turbines.

These turbines are of the “bunny ear”configuration,whicmeans

that two of the blades are already installed onto the turbine hub pointing skywards in a V shape. The Nacelle blade assembly can then be lifted and secured followed by the installation of the third blade.