Largest ever Rotortugs for Shell’s FLNG facility

KT Maritime Services has now taken delivery of three large tugs with European influence in what can perhaps be considered one of the most significant and interesting items of new delivery news in 2016.

KT Marine Services Australia Pty, a JV of Kotug International BV and Teekay Shipping Australia Pty recently christened RT Beagle Bay, RT Roebuck Bay and RT Kuri Bay destined to provide an array of services at Shell’s Prelude floating LNG facility off northwest Australia. The result is a combination of Robert Allan’s RAstar style hull and Rotortug propulsion technology with the 100tbp ART 100-42 design.

The multirole requirement is reflected in their designation as Infield Support Vessels described as ‘modern high-performance tugs custom designed to meet Shell’s demanding requirements.’ As well as forming an integral part of the facility’s security, emergency response and evacuation requirements tasks include escorting and berthing LNG carriers, condensate tanker tow-backs, pilot transfer and floating hose handling.

Built by ASL Shipyards Singapore the specifications are impressive. High environmental standards required that all fuel, lube oil and other pollutants be located off the vessels’ shell, a requirement described as ‘extremely challenging’ for a 42m vessel with fore and aft propulsion systems and very high fuel oil and fresh water capacities required for a 35-day offshore endurance with reserve. Reduction in motions and accelerations of the RAstar hull (compared to more standard wall-sided hull forms) will provide the required seakeeping performance in high sea states.

Turning to details of the vessels, their scale is reflected in main particulars of: length 41.95m, beam 16m, depth 6.6m, loadline draught 7.9m and a GT of 1133t. Tank capacities include: fuel oil 445m3 (at 95%), fresh water 73.2m3, foam 5.7m3 and dispersant 5.7m3.

Niigata provide the main machinery with three IMO Tier II compliant 6L28AHX main engines, each rated 2,200kW at 800rpm. These drive three Niigata ZP 21 Z-drives in standard Rotortug configuration of two forward and one aft, each with fixed-pitch propellers and idle slipping clutches. Auxiliary machinery includes three CAT C9 gensets providing 200ekW at 1,500rpm and a CAT C4.4 radiator cooled emergency genset rated 82ekW at 1,500rpm.

As to be expected the deck equipment is extensive with Kraaijeveld providing electric escort/towing winches forward and aft. Forward is a SafeWinch model KASW-30-E-TR/28/29 escort winch featuring split-drum, two wildcats, single warping head and spooling gear. On the aft deck an escort SafeWinch KASW-30TR features a single drum with capacity for 350m of 80mm synthetic rope with spooling gear.

Additional deck equipment includes: a 50t/m deck crane, Kooiman retractable towing fairlead (Omega Pin), Kooiman Delta pins with chain stopper for hose handling, two 10t tugger winches and a 5t vertical capstan. The vessels meet fifi1 standards from a 2,850m3/hr pump driven off the port main engine and supplying two 1,200m3/hr monitors, self-drenching water spray along with a 300m3/hr foam system capability from the starboard monitor.

Additional emergency response arrangements include a Norsafe 6.55m jet-powered Maki FRC serviced by a Redrock luffing davit, Dacon scoop and scramble net and six 50-person inflatable liferafts. An extensive survivor capacity was specified requiring space for 85 persons.

Eight MLC compliant crew cabins are provided, four single cabins on the forecastle deck and one single and three double cabins on the main deck one of which is designated as a recovery room for four survivors. The large survivor capacity of the vessels is evident with provision of a reception area and treatment room on the main deck which also houses the galley, mess, dry and cold store and laundry.

The layout of the wheelhouse is worthy of mention with conventional split consoles both fore and aft each with its own separate master’s chair running in between. Such a configuration allows a clear line of sight both forward and aft, particularly important when carrying out hose-handling and pilot transfers along with emergency operations involving deployment of the FRC and Dacon scoop rescue.