A new type of escort tug is under construction in Turkey with a shallow draught and almost 85 tonnes of bollard pull
Demand for escorting larger ships in shallower waterways has driven a Turkish shipbuilder to construct a new design of escort tug.
Sanmar Shipyards is building 32-m Kocaçay-series tugs to a Robert Allan design, with the first set to be deployed in northern Scotland. These will be built to a RAstar 3200-SX design with a maximum navigational draught of 5.5 m.
Kocaçay series vessels are built to applicable rules and regulations of either Bureau Veritas or RINA classification societies for an escort and fire-fighting FiFi1 tug.
Robert Allan said this series has shallower draughts than other comparable high-performance escort tugs. “This design includes optimisation to minimise construction costs without reducing end-performance,” said the naval architects. Designers used feedback from companies already operating Sanmar-built and Robert Allan-designed tugs for this new series.
RAstar 3200-SX design, 407-gt tugs have a moulded beam of 13 m and hull depth of 5.4 m and are twin Z-drive, diesel-powered vessels equipped for operations over the bow and stern.
RAstar 3200-SX will have bollard pull of up to 84 tonnes ahead and 77 tonnes astern, plus free running speed of 13 knots.
Their main propulsion will include a pair of Caterpillar 3516C diesel engines, each rated at 2,350 kW or 2,525 kW at 1,800 rpm, driving two Rolls Royce US 255 P30 controllable-pitch propellers of 2.8 m diameter in Z-drive units.
These Kocaçay series tugs will have a winch at the bow for escorting and ship handling operations, and a towing winch, towing pins and rounded transom at the stern.
Robert Allan said testing the tug design using escort analysis software indicated RAstar 3200-SX tugs could safely escort ships at up to 10 knots with predicted steering forces over 70 tonnes and braking forces of almost 120 tonnes.
For optimised ship-handling, they have been designed with fenders at the bow consist of one tier of 900 mm outside diameter and 550 mm inside diameter cylindrical fendering at the main deck level. They have 48-30 W-type fenders between the raised forward deck and the knuckle. There are also hollow 300 x 300 mm D-type fenders at the main and forecastle sides and sheer lines, and 48-30 W-type fendering at the stern.
The first of the RAstar 3200-SX design, Kocaçay series tugs are being built by Sanmar for Orkney Islands Council Marine Services.
RAstar 3200-SX particulars
Designer: Robert Allan
Builder: Sanmar Shipyards
Length, oa: 32 m
Beam, moulded: 13 m
Draught: 5.5 m
Gross tonnage: 497 gt
Free running speed: 13 knots
Ahead bollard pull: 84 tonnes
Astern bollard pull: 77 tonnes
Main engines: 2 x CAT 3516C
Propulsion: 2 x Rolls Royce US 255 P30 CP Z-drive
Fuel oil: 164 m3
Potable water: 20 m3
Sludge tank: 7 m3
Grey water: 9.3 m3
Sewage: 9.3 m3
Foam: 9 m3