Flexible pipelaying vessel SEVEN SEAS

SEVEN SEAS has been designed by Merwede Shipyard in close co-operation with Subsea 7 and the Huisman-Itrec. The vessel is intended primarily for flexible pipelaying operations with an additional J-lay capability. The multipurpose lay-tower is situated aft of the ROV hangar and accommodation block. It consists of two aligner chutes, one on port and one on starboard and an enclosed welding station for J-lay operations. The tower is equipped with an electrically driven upper 170t flex tensioner and electrically driven main tensioner with a 200t flex-rating and 400t rigid-rating. In both flex and J-lay mode up to 24. diameter pipe can be deployed. A 450t and a 125t A+R winch are provided.

The midbody of the SEVEN SEAS incorporates a large moonpool  (7x7.5m). It is closed by sliding hatches at deck level; the hatches have a hang off capacity of 600t SWL. The moonpool’s hinged bottom door is constructed in such a manner that it streamlines the flow under the vessel whilst sailing. In open position, the door forms part of a damping cofferdam structure that prevents surge in the moonpool during operations.

Aft of the moonpool, a hold has been arranged to accommodate two carousels, each with an external diameter of 16m and capacity of 1250t. On the main deck there is an open deck area of 1750m2, with a deck load capacity of 10t/m2 or a deck carousel up to 24m diameter and 3000t capacity, where reel drive system can be located.

The diesel-electric power plant features six Wärtsilä gensets of 3360kW/3600kVA each. The emergency/harbour genset consists of a 1500 kWe (440V, 60Hz) Volvo Penta D65 A MS engine and AvK type DSG 86 M1-4 generator. Propulsion and dynamic positioning DP2 is established by means of three 2950kW azimuth stern thrusters, two 2400kW retractable azimuth bow thrusters, a 2200kW bow thruster – all Wärtsilä – and a Kongsberg Simrad SDP 22 DP system.

Length, oa: 153.24, Length, bp: 138.22m, Beam, mld: 28.4m, Depth, mld to the main deck: 12.5m, Design draught: 7.5m, Deadweight, design: 11,130dwt, Output: 6x3360kW, Main propulsors: 3x2950kW azimuthing thrusters + 2x2400kW retractable bow thrusters, Service speed: 13.0knots, Accommodation for 120 persons.

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