AOS Power: First RAmpage 4500 Class Offshore Support Tug

by Hans | February 28th, 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                                             -45.00 metres

Beam, moulded, extreme                            -15.00 metres

Depth moulded (hull)                                   -6.75 metres

Design draft, to USK                                  -4.60 metres

Summer loadline draft                                -5.55 metres

Tank Capacities are as follows:

Fuel oil                                                              -525 m³

Potable water                                                  -115 m³

Drill water                                                       -140 m³

Ballast water                                                  -145 m³

Foam                                                               -20 m³

Oil dispersant                                                -15 m³

Lube oil, main engines                                  -12 m³

Lube oil, auxiliary engines                             -2 m³

 Z-drive gear oil                                             -2 m³

Hydraulic oil                                                  -3 m³

Dirty oil                                                         -7 m³

Oily water                                                    -6 m³

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

BV 1 X HULL, X 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 aft 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. 


Electrical power is supplied by a pair three Cummins 6CTA-M diesel gensets, each Rated 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                                         -70 tonnes at 100% MCR Free running speed                                        -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 Class was developed by Robert Allan Ltd. to address a perceived gap in the market for 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 Class vessels, please contact Robert Allan Ltd. at

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