The shallow draft tug AK Bars nears completion at Hepworth

All have been built to fulfil a particular role in Holyhead Towing’s continually expanding fleet of vessels required to serve the company’s core business; supporting dredging, coastal improvement, windfarm construction, cable-laying, and a host of other marine civil engineering projects. The resulting six vessels have varied in size from 22.5m to 35m in length and the design process has been a joint effort between the shipyard and Holyhead’s own technical and operations staff.

Named AK Bars, the seventh and latest vessel to be constructed for Holyhead Towing breaks new ground on two counts. The tug has been designed entirely ‘in house’ by the Welsh towage company and is a new 25m, shallow draft, twin screw, ice class vessel capable of fulfilling a wide range of services in the oilfields of the Caspian Sea. A true ‘maid of all work’, the AK Bars is designed and equipped for towing, pushing, anchor handling, cargo and personnel transportation, and the delivery of fuel and water in and around the shallow waters of the oilfields. The tug will be operated by Holyhead Towing’s joint venture company Caspinsky Buksir based in Kazakhstan, and registered in Cyprus.

AK Bars is designed and constructed to comply with the requirements of Lloyds Register of Shipping + 100A1 Tug, Ice Class 1B, +LMC, Unrestricted service. The single chine hull has an overall length of 25.00m (excluding fenders), a substantial moulded breadth of 9.50m, a moulded depth of 3.25m and a working draft of 2.00m to 2.50m. The hull was fabricated by Aveco in Middlesbrough and towed down to Paull for completion.

In order to meet the shallow draft requirement and maintain maximum buoyancy for anchor handling and load carrying, the propellers and fixed nozzles of the twin screw propulsion system are located in tunnels beneath the stern. The broad flare of the chine in the bow incorporates a transverse bow thruster and a substantial single ‘push knee’ is built into the stem. The fendering includes steel rubbing strakes of half-round section around the bow and on each forward shoulder, overlaid with vehicle tyres. A square section rubber moulding encircles the sides and aft quarters, at deck level. The open stern incorporates a substantial stern roller and the bulwarks have openings, just aft of amidships, to allow hoses etc to be taken across the deck.

An important feature of this new design is the large clear after deck, intended to afford an ample work space and a useful cargo capacity. The deck has the usual hardwood overlay for protection and has the appropriate fastenings for the carriage of standard ISO containers. Integral tanks are provided for 100cu/m of fuel, 45 cu/m of fresh water, 9 cu/m of sewage and the necessary high performance transfer pumps are provided for the delivery of fuel and water to vessels or plant.

The propulsion system aboard AK Bars comprises an engine-gearbox package supplied by Cummins. Two KTA 38 M1 engines, each rated 1,100bhp at 1800 rpm, transmit their power to twin fixed pitch propellers via ZF W7500 ice class 1B gearboxes with a reduction ratio of 4.939:1. The four blade propellers measure 1,600mm in diameter and rotate within fixed Kort nozzles. A high lift, fishtail, rudder is mounted aft of each nozzle and is given some protection by a small ‘ice knife’ located in the top of each tunnel. The steering gear was supplied by WK Hydraulics.

Although trials had not been carried out at the time of writing, a bollard pull of 25 tons is anticipated, along with a maximum free running speed of about 11 knots. To aid manoeuvrability a 150hp, hydraulically powered Kort KT150 transverse bow thruster is installed.

Electrical power is supplied by two 78kW generating sets, both powered by Cummins 6B5.9D2(M) engines and supplied by Pelican Engineering. One engine is radiator cooled and the other via box coolers along with the main engines and other auxiliaries. Also installed in the engine room is a Cummins 6CT8.3 D (M) diesel rated at 188bhp at 1,800 rpm and used to drive the hydraulic pump supplying the deck machinery and bow thruster.

Other items of equipment include a WWT 1 Biopur sewage treatment plant supplied by RWO Marine Water Technology and a H208A fresh water maker supplied by Seafresh Desalinators Ltd. The vessel’s electrical system was installed by Hull based Humber Electrical.

North Sea Winches supplied most of the deck machinery including the main towing and anchor handling winch. The hydraulic winch has a single ‘spilt’ drum with a maximum line pull of 45 tons and a maximum brake holding capacity of 80 tons. The largest partition on the drum can carry up to 500m of 38mm diameter steel wire towline and the remainder a shorter ‘work’ wire. Hydraulically operated spooling gear is fitted and can be operated automatically or manually. Located aft of the winch are ‘Dutch’ style bitts which act as a fairlead for the winch wires and form an integral base for the deck crane. Adjacent to the towing and anchor handling winch, on the starboard side is a 9 ton hydraulically power tugger winch and its associated fairlead. Also fitted are hydraulic tow pins and hook from Western Machinery Works and a quick release tow hook. North Sea Winches also supplied the anchor windlass on the fore deck and installed the entire hydraulic system for deck machinery, crane and bowthruster.

In common with all multipurpose work vessels of this type, a deck crane is fitted for handling stores, equipment and providing lifting services on site. AK Bars is equipped with a HS Marine hydraulic crane type AKC 115 HE4, with four telescopic jib sections and a maximum outreach of 14.01m. The crane is rated at 90 t/m and can lift 18 tons at 4.5m and 6 tons at 12.5m.

Accommodation is provided for a maximum of 12 persons in six cabins fitted with air conditioning and heating suitable for operation during the cold north Caspian winter. Insulation, wall boards/deckheads, furniture and outfitting was supplied by Promat UK.

The wheelhouse is a compact structure surmounting the single storey accommodation block and affording very good all round visibility. A series of windows overlooking the after deck, extend to floor level and give a particularly good view of the work deck.

Navigational equipment installed includes two radar sets, a magnetic compass, auto-pilot, electronic chart plotter, GPS, and echosounder. A communications outfit is installed to the appropriate GMDSS level for the operational area and includes the normal VHF radios, MF/HF single side band radio, Imarsat C, Navtex and an Iridium satellite telephone with Email. The electronics were supplied and fitted by Boat Electrics and Electronics Ltd.

AK Bars is due for completion and handover in mid-June, after which it will sail for the Caspian Sea. It will operate in the Kashagan oil field around ‘D Island’, providing a whole range of transportation, towing, anchor handling and other supporting services. Also operating under Caspinsky Buksir is the multi-purpose work vessel AK Tue, the shallow draft tug AK Sunkar, and the 35m tug AK Burkut , delivered by Hepworth last year.

Hepworth Shipyard is currently building a sister ship to the AK Bars. This further vessel will be built and fitted out entirely at Paull on Humberside and will become part of the Holyhead Towing UK fleet. In most respects it will be identical but the Cummins KT 38 main engines will be uprated to 1,300 bhp, increasing the bollard pull to approximately 27-28 tons.

By Jack Gaston