January 20, 2009
New Robert Allan ASD tug class
Recently delivered to Norwegian owners Østensjø Rederi AS by Sanmar Denizcilik Makin eve Ticaret Ltd., of Istanbul, Turkey, Vivax is the first in a new class of ASD (azimuthing stern drive) tug.
It is similar to a successful line of Robert Allan Ltd. design 32 meter RAmparts 3200 Class tugs built by Sanmar, but with higher power and a more extensive equipment outfit. Meeting Østensjø's requirements led to a close collaboration between owner, builder and designer to develop a revised, beamier design that would meet Østensjø's needs and standards, while also respecting the builder's normal procedures and standards for new construction.
The hull form reflects the now very well-proven double chine form that characterizes all Robert Allan Ltd. designs, with a sweeping "chined" stern. A large escort skeg fitted forward enhances the indirect towing capability roll stability.
Designated the RAmparts 3200B Class by Robert Allan Ltd. and as the "Eskort 80" by Sanmar, the new ASD class tug is suitable for a range of duties, including harbor towage and ship-handling, coastal towing, and escort operations. It is also equipped for firefighting and oil spill response.
The first of Class Vivax has the following particulars:
Length Overall 32.00 m
Beam, Molded 12.00 m
Depth, Molded 5.36 m
Maximum Draft (overall) 6.11 m
Power 4,800 kW
The tug is classed by ABS: Towage Service, Escort Vessel, ABCU, Fi-Fi 1, Oil Recovery Class 1, Unrestricted Service. On trials the vessel achieved a mean bollard pull of 80 tonnes, and a free-running speed of over 14 knots.
Features of the RAmparts 3200B design include a large aft deck with side crash rails to facilitate towing and oil recovery operations; and a half-raised forecastle running nearly half the length of the tug to provide a high standard of accommodation and a good sea-keeping capability for operation in exposed conditions.
The vessel has been outfitted to the highest standards for a crew of up to six. The main deck features a master's cabin with en-suite facilities, a ship's office and a crew mess/lounge, served by a fully equipped galley. The lower deck contains the chief engineer's cabin, also with ensuite plumbing, and twocrew rooms, equipped for either single or double occupancy. These two (2) crew rooms share access to a common lavatory space. The wheelhouse is designed for maximum visibility with a single control station providing maximum visibility to both fore and aft deck working areas. Noise levels throughout the accommodations and control spaces of the tug are about 60 dBA, thanks to advanced methods of isolating main propulsion machinery, as well as high grade insulations and floating floor techniques.
Main propulsion is by pair of Wartsila 8L26 diesel engines, each rated 2,400 kW at 1,000 rpm, and each driving a Rolls-Royce model US 255 Controllable pitch Z-drive unit in ASD configuration. The indirect escort steering force, yet to be exercised at full-scale, is estimated at 80 tonnes at 10 knots.
The electrical plant comprises two identical diesel gen-sets, each with a 400 volt/50 Hz. power output of 120 kW. A 40 kW harbor gen-set is also provided.
Fire-fighting is to Fi-Fi 1 Class, using FFS pumps and Monitors.
The main hawser winch forward is a single drum type, containing 150 m of high-performance UHMWPE towline. Aft there is a double-drum towing winch, each side of which carries 950 m of 52 mm steel wire rope. Both winches are Rolls-Royce supply. The aft deck is also served by a 65 t-m capacity knuckle boom crane.
Ship-handling fenders at the bow comprise a 900 x 450 cylindrical fender above a row of 450 mm "W" block fenders. A 300 x 300 hollow "D" fender provides protection at the main and forecastle deck sheer lines, and "W" block type fendering is used again at the stern.