Anchorhandlers – an example of the next generation

A brief look at a series of four new anchorhandling supply vessels being put into service in the Far East by Go Offshore (Asia) Pte Ltd shows what the latest generation has to offer.

Two vessels, Deep Sea 1and Go Phoenix, are in service, Go Pegasus is nearing completion and a fourth was under construction at the time of writing. All four are products of the BATAMEC Shipyard at Batam, Indonesia.

The vessels are built to the ‘VS 491 CD AHTS’ design and measure 81.97m in length overall with a breadth of 21.95m, a depth of 9.56m and a maximum loaded draft of 8m. These are real monsters, with a gross tonnage of 7,531 and 4,500 tonnes dead weight and a DNV class to match, with the impressive notations +1A1 ICE-C Tug Supply Vessel, Fire Fighter 1SF COMF-V(3) EO DYNOPOS-AUTR NAUT-OSV(A)CLEAN DESIGN DK(+)HL(2.8)BIS TMON.

In addition to an impressive cargo capacity, in dedicated tanks and on deck, Go Phoenix and its sister ships are equipped for towing and anchorhandling under the most demanding conditions. On trials the latest vessel, Go Pegasus, achieved a bollard pull of 257 tonnes and a maximum speed of 17 knots. An economical service speed is given as 13 knots and a bollard pull at MCR of 245 tonnes.

Two MAK 16M32C main engines generate a total of 21,456 bhp (16,000kW) at MCR to drive a pair of Scana controllable pitch propellers rotating in fixed nozzles. Each main engine also drives a 4,500kW shaft generator which, with two diesel powered auxiliaries, supply the vessel’s thrusters and the ship’s systems.

Two 880kW transverse thrusters are installed in the bow along with an 800kW retractable azimuthing unit and two 800kW transverse thrusters at the stern. The main engines, propellers, rudders and thrusters can be operated under ‘single lever’ control and full dynamic control via a Kongsberg KOPos DP-2 system.

At the heart of these vessels is a massive Hatlapa waterfall style towing and anchorhandling winch. The drums have a brake holding capacity of 600 tonnes (on the first layer) and a line pull of 500 tonnes at 17.5m/min. Two towing drums, of different diameters, can take 1,500m of 90mm SWR and the anchor handling drum a 90mm work wire of 1800m in length. Powered storage reels can accommodate 4,000m of 75mm SWR.

Extensive arrangements are also provided for the storage and handling rig mooring chain. The stern roller is rated at 600 tonnes SWL, the Triplex ‘Sharks jaw’ line handling gear 750 tonnes SWL, and the Triplex retractable tow pins 350 tonnes SWL. Two 25 tonne tugger winches are are also installed and deck cranes, port and starboard, with 6 tonnes capacity at 17m reach.

Accommodation aboard these massive vessels is provided for up to 60 persons.