Afon Cefni – Custom Built for Holyhead Towing

In keeping with several other vessels owned by Holyhead Towing the tug has been custom built to meet the needs of the company’s core business; to support dredging, coastal improvement, cable laying, and a host of other marine civil engineering projects.

Hepworth Shipyard and Holyhead Towing have developed a close working relationship over a period of several years, with the building of the Afon Goch which started in 1996, and which has included some major refits, such as the Afon Wen 18 months ago.

From this close relationship Hepworths have developed a very good understanding of the problems encountered in the very demanding environment in which the vessels work, and that knowledge has been put to good use in the design and construction of this practical workboat. She was named by Sue Coates, widow of the late Dick Coates who looked after engineering at the yard for many years until his untimely death early last year, and at the ceremony Mark Meade expressed his delight in the quality of the construction and engineering in this sturdy and well laid out vessel.

Afon Cefni was designed by Hepworth Shipyard, working in close collaboration with Holyhead’s managing director Capt Mark Meade and the company’s technical staff.

Among the main requirements were; the ability to carry out coastal towing operations with marine plant and barges, dredging with a towed plough, anchorhandling, lifting, and providing a wide range of other supporting services on site. The vessel is designed to meet the requirements of the UK MCA Workboat Code of Practice – Category 2 – up to 60 miles from safe haven; Bureau Veritas Tug Coastal Waters – Loadline Certificate.

The tug is of all steel, welded, construction with an overall length of 22.5m, a beam of 7.5m and depth of 3.25m. A shallow draft of approximately 2m is an important feature and obviously dependent on loading and trim.

A single chine hull design was chosen, from previous experience, in order to achieve the necessary shallow draft, required buoyancy and sea-keeping characteristics.

The hull is heavily constructed with transverse framing and 10mm and 12mm shell plating.

As with all vessels built by Hepworth, steel approved to Lloyds Grade A, was supplied by Dent Steel Ltd. A semi-raised foredeck affords some protection when at sea and the bulwarks are ‘stepped in’ to prevent damage when working alongside and provide safer access for personnel.

Openings in the bulwarks amidships enable dredge-hoses and similar components to be brought aboard to enable work to be carried out on deck. The open-stern is fitted with a stern roller with a safe working load of 50 tonnes manufactured by ACB Ltd.

The hull structure also incorporates a survey ‘moonpool’, located amidships, inside the bulwarks. Rectangular, moulded rubber, fendering encircles the vessel and a single ‘push-knee’ is fitted in the bow. All moulded rubber sections were supplied by Sovereign Rubber Ltd. . .

. .Internal tanks fitted amidships have a fuel capacity of approximately 47m 3. Domestic fresh water tanks have a capacity of 10.7m 3and additional tanks for ballast and supplies have a total capacity of 71m 3. Two electrically operated, high capacity, Desmi pumps enable fuel and water to be transferred to other vessels and plant at a rate of 50m 3per hour. A hose reel and dispenser for diesel fuel is fitted on deck aft of the superstructure.

Afon Cefni has a conventional twin-screw propulsion system powered by two Cummins KTA 19M3 main engines running at 1800 rev/min to produce a total of 1300bhp. Power is transmitted through a pair of Twin Disc MG5170 DC reverse reduction gearboxes to fixed pitch propellers, rotating within Kort nozzles. The fixed nozzles are set in shallow tunnels in the hull in order to meet the shallow draft requirement. Twin rudders, of Hepworth’s own semi-balanced, high lift, ‘fishtail’ design are fitted and controlled by Servi electrohydraulic steering gear from a ‘jog lever’ in the wheelhouse.

On trials, Afon Cefni achieved a bollard pull of 17 tonnes towing ahead, with an astern pull of 10 tonnes, and a free running speed of 11 knots. The inherent agility of this small twin-screw tug is enhanced with a transverse bow thruster from Kort Propulsion.

The thruster provides 860kg of thrust and is powered by a 120hp hydraulic motor supplied from the ship’s main hydraulic system.

Electrical power is provided by 40kVA generator sets powered by Cummins 4B 3.9 – D(M) engines, one with closed circuit radiator cooling to ensure that power is available under any circumstances. A third, larger 6 cylinder Cummins diesel drives the necessary pumps for the deck hydraulic and bow thruster systems. North Sea Winches Ltd, suppliers of the winches and windlass, were also responsible for the hydraulic power-pack installation.

On deck Afon Cefni is fitted with a North Sea Winches hydraulic towing and anchorhandling winch with a single split drum. The winch has a maximum line pull of 36 tonnes at 8m/minute and a brake holding load of 54 tonnes. Aft of the winch is a ‘Dutch style’ towing bollard and fairlead, that also provides a mounting for a Britannia, rotating disc, quick release towing hook with a 20 tonnes safe working load.

On the foredeck the vessel’s single anchor, and 17.5mm stud-link chain, is handled by a small hydraulic windlass.

A useful storage hold for marine equipment and spare gear is located between the engine room and steering flat.

The afterdeck has a large clear working area protected with hardwood cladding, and as previously mentioned the open stern is provided with a stern roller for anchor-handling.

Fittings are provided on deck for a demountable 30 tonne ‘A frame’ for plough dredging and similar operations, utilising the same towing and anchorhandling winch. A major facility aboard Afon Cefni is the powerful 65 tonnes/metre Effer crane supplied by European Crane Services. The hydraulically powered, long reach ‘knuckleboom’ crane, designated 65000-3Sl, is capable of lifting 11,400kg at 5.2m reach and 4,900kg at 11.50m. A lifting winch, wire and hook is also incorporated.

A neat well-designed superstructure is surmounted by a spacious wheelhouse intended to give good all round vision and flexibility of use. In addition to an array of modern navigational and communications equipment, provision is made to accommodate additional sophisticated survey equipment and the necessary staff. A full width console at the forward end of the wheelhouse incorporates a central control position with all of the normal propulsion and steering controls.

A second control station is located at the rear of the wheelhouse with an exceptional view of the afterdeck. The autopilot is an AP 45 system from Robertson.

Located on the forward console are display screens for the Simrad RA 53C ’15 colour’ radar, Furuno Navnet LCD radar, and the Winfish GX Pro 11 electronic chart display. A high degree of integration allows multiple display options on a single screen, such as the overlaying of charts, radar and GPS information. Likewise, the two radar plots, each set to a different range, can be displayed side by side on one screen.

Images from a closed circuit television system, used to monitor the engine room and winch, can also be shown in any of up to six ‘windows’ available on one multiple display.

Also located on the main console is a Simrad EQ60 38/200 KHz survey grade dual frequency echosounder, complete with printer and data output. . .

. . A portable computer keyboard, with an infra-red interface, is used to control many of the equipment functions on the console. Navigational equipment also includes a magnetic compass, a Furuno Satellite SC-60 GPS compass, a Furuno Navtex NX-300 and an MLR FX 412 GPS. Furuno FM-2721 VHF radios, with DSC, are installed along with a Raytheon intercom system and the usual GSM mobile telephones.

A surveyor’s desk is provided, with the necessary power supplies for additional equipment.

Both wheelhouse and accommodation are fitted out and finished to a very high standard. Under normal circumstances a crew of three will be carried, depending on the work in hand, but accommodation has been made available for survey or contractors’ staff.

Six cabins, each with an additional ‘Pullman’ style berth, enables a total of twelve personnel to be housed in reasonable comfort. The usual mess room, galley, washing, drying and storage facilities are included.

By mid April, following the completion of commissioning and trials, Afon Cefni sailed from the Humber to take up station on the north west coast of Scotland where she will be employed for the next six months. The tug will be carrying out exactly the type of work for which she was designed – supporting the construction of new ferry facilities on the Isle of Eigg in the Scottish ‘Small Isles’.

Holyhead Towing are working under contract to R J McCleod (Contractors) Ltd who are carrying out the work on behalf of the Highland and Islands Council. Afon Cefni will be used for the duration of the project along with a 60 metre barge to transport plant and materials to and from the site, which is accessible only by sea. In this role the vessel will perform a wide range of supporting services, almost exactly those described in the initial builders specification, demonstrating the advantages of a true ‘custom built’ vessel.

MJ Information No: 16901