AOS Power – First RAmpage 4500 Class offshore support tug

February 27, 2012


In December, 2011, the tug AOS Power was delivered to her owners Atlantic Maritime Group, Sharjah, UAE. Designed by Robert Allan Ltd. of Vancouver, Canada and built by GMG Shipbuilding & Heavy Industry Co. Ltd., China, AOS Power is the very first of the RAmpage 4500 class design. This vessel is fully equipped for anchor handling, ship-assist, long distance towing operation, fire-fighting, deck cargo transfers, personnel transfer and other offshore support duties.


The particulars of this tug are as follows:

Length overall
Beam, moulded
Depth moulded (hull)
Design draft, to USK
Summer loadline draft
– 45.00 metres
– 15.00 metres
– 6.75 metres
– 4.60 metres
– 5.55 metres


Tank Capacities are as follows:

Fuel oil
Potable water
Drill water
Ballast water
Oil dispersant
Lube oil, main engines
Lube oil, auxiliary engines
Z-drive gear oil
Hydraulic oil
Dirty oil
Oily water
– 525 m³
– 115 m³
– 140 m³
– 145 m³
– 20 m³
– 15 m³
– 12 m³
– 2 m³
– 2 m³
– 3 m³
– 7 m³
– 6 m³


AOS Power has been built and classed to Bureau Veritas Notations:


BV 1 HULL, MACH, Tug special service, Anchor handling, Fire-Fighting ship 1+ Waterspray, Unrestricted navigation.



The vessel has been outfitted for a crew of up to 25 people, although normal operating crew is 15. The deck machinery comprises a single drum Hawser winch at the bow, a water-fall double drum Towing Winch on the deck together with other deck machinery to fulfill operation requirements such as stern roller, shark’s jaw-top pin unit, gobeye, deck crane, tow hook, tugger winches, capstans, storage reel, etc. The large main deckhouse contains a spacious galley and mess, cabins for senior officers, guests are placed on “A” deck, HVAC Room, lockers, etc. The lower deck contains galley stores, cold storages, laundry room, engineer stores, workshop, etc. The Wheelhouse is designed for maximum all-round visibility with forward and aft control stations providing maximum visibility to both fore and aft deck working areas.

The propulsion machinery comprises a pair of Wärtsila 6L26 diesel engines; each rated 2040 kW at 1000 rpm and each driving a Lips CS250 cp unit.

Manoeuvrability is enhanced by a 400 kW controllable pitch electric bow thruster. Electrical power is supplied by three Caterpillar C18 gensets, each rated at 500 kW.

Emergency power is provided by a Cummins 6CTA-M diesel genset, rated at 95 kW.

Ship-handling fenders at the bow comprises rubber fenders of 900 x 500 cylindrical and W48-30. A 300 x 300 hollow “D” fender and aircraft tires provide protection at the main and foc’sle deck sheer lines, and 300 mm “W” block type fendering is used at the stern.


On trials, AOS Power met all performance expectations, with the following results:


Bollard Pull, ahead
Free running speed
– 70 tonnes at 100% MCR
– 13.9 knots


This new RAmpage 4500 class tug is the newest member of the very successful RAmpage series of Offshore Support Tugs. The RAmpage Series was developed by Robert Allan Ltd. to address a gap in the market for smaller high-performance towing and anchor-handling tugs for critical offshore terminal and oil-field duties. These RAmpage tugs are designed to be able to maintain station in extreme ocean conditions, with enhanced manoeuvring and sea-keeping capabilities.

For more information on the AOS Power or any other RAmpage Series vessels, please contact us at