FAR SAMSON is the most powerful offshore vessel ever built. The vessel is initiated by Farstad Shipping of Norway, and realized by Rolls-Royce in close co-operation with the Owner. Rolls-Royce developed the special design based upon Farstad’s requirements, and the UT 761 CD has been built by STX Europe Langsten.FAR SAMSON is the most powerful offshore vessel so far, with a continuous bollard pull of 423 tonnes with all 3 auxiliary thrusters operating and 377 tonnes under main propellers alone.
The UT 761 CD is a design specially developed to meet a strict set of requirements from the Owner, and incorporates new technology. It is a multifunctional vessel capable of carrying out heavy ploughing operations for pipes and cables on the seabed, sub sea installation work in ultra deep water, ROV operations, towing, and other challenging subsea operations. The specification calls for ploughing to a cut depth of 2.5m in the seabed in water up to 1,000m deep.
Meeting the various demands means a large vessel, 121.5m long overall, 26m beam, 15,620 gross tons, the hull strengthened to Ice Class 1B, having also DeIce Class for operation in iced waters and harsh conditions. Hull lines are optimised for the required 12-17 knot transit speed range, allowing the ship to mobilise efficiently for operations anywhere in the world. The top speed is approx. 20 knots. The draught is more than 8 m to give sufficient immersion to the large propellers. The hullform incorporates a bow bulb and stern sections designed to give a clear flow of water to the propellers to satisfy the requirement for an extremely high bollard pull.
During design and construction of this Clean Design vessel, utmost attention was paid to internal and external environmental aspects as well as the safety conditions for vessel and crew.
An unusual feature of the UT 761 CD is two working deck levels. The space over the main deck houses the winches (Rolls-Royce 600 tonne pull hydraulic main winch) and is open at the stern, allowing wires to be run over a stern roller. It is flanked by workshops and winches for the A-frame and crane. Above it is the working/weather deck fitted with a track system and transportation skids provided for deploying either of the two massive ploughs offshore. An A-frame with a 250 tonne safe working load offshore and active heave compensation winch is mounted at the aft end of the deck.
Between the working deck and the accommodation is a large ROV hangar. A 7.2m x 7.2m moonpool is provided amidship. Equipment can be deployed through the moonpool using the offshore crane which is rated for a 250 tonne lift up to 35m outreach and 3,500 m working depth. Because of the high asymmetric loads, the ship will have an active heel control system as well as passive roll reduction tanks. Ahead of the plough garage is an ROV hangar and deployment system.
FAR SAMSON has a hybrid propulsion combining diesel electric and diesel mechanical transmission to give optimal operating flexibility, fuel economy and minimum exhaust emissions. Depending on the type of operation, the UT 761 CD can run in any of six principal propulsion modes. This flexibility means that the widely varying power requirements are efficiently catered to, there is a high level of propulsion redundancy, and engines are run at an efficient part of their load range, minimising exhaust emissions. All Bergen engines meet Clean Design class rules without further exhaust clean-up, but catalytic converters are additionally fitted to the gensets, giving 95% NOx reduction.
To meet IMO DP3 requirements the machinery is split between two engine rooms separated by a longitudinal watertight bulkhead. Each of the two main CP propellers has an output of 12,000 kW. There are four auxiliary generator sets.
Aft are two 1,200 kW tunnel thrusters and an 1,800kW swing up azimuth thruster. Forward there is one 1,800kW tunnel thruster, a swing-up azimuth unit of the same power and an 1,800kW Combithruster.
One major role for the new Farstad vessel will be pipeline trenching with a new generation plough that is capable of cutting a 2.5m deep trench in the seabed allowing for larger pipe diameters and giving the pipe better protection. FAR SAMSON can pull this plough in the water depths that will be called for in the future. The main plough cuts the trench and places the pre-laid pipeline in it in one operation and a separate backfill plough is used later to backfill the trench. When not in use the main plough is housed in a large hangar on deck where it can be maintained under cover.
To move these heavy pieces of equipment on deck safely and under full control, there is a special skid handling system allowing one plough to be parked on the centreline under the hangar, the other overhanging the deck edge to port. Being able to change the ploughs offshore, eliminating the need for port call for plough change, as well as being able to carry both ploughs in fully operative condition on deck at all times, will be a great advantage for the operation.
Far Samson has accommodation to Farstad’s high standard meeting Comfort class (V3)(C3) rules. Since the type of operations to be undertaken involve large numbers of people, a total of 22 single cabins and suites and 39 double cabins are provided, together with all facilities including messes, cafeteria, dayrooms, gymnasium, hospital, offices and conference rooms, spread over six decks. There is a central lobby and lift to the various levels, while the layout allows easy movement of people around the ship.
A distinctive feature of the design is a double deck bridge layout. The navigation wheelhouse follows current UT-Design principles, with a semicircular bridge front and the main forward facing control station for transit and navigation placed for optimum sight lines. Communications and a client/ROV service area are located in the centre with the casings either side, and at the aft end, commanding a clear view over the deck and the area around the ship, is the manoeuvring console.
On the deck below is a second set of consoles enjoying a good view over the working deck, from which ploughing and other winch operations can be controlled. DP3 and other controls are also slaved to this position. On the same deck is a plough/control/survey space, an instrument room, suites of offices and a conference room. There is a separate ROV control room, and a new engine control room concept has been developed by Rolls-Royce for Farstad particularly for this vessel.
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