The Afon Dyfrdwy: Wings Under the Bridge

295
April 2005

The chorus for the American folk song "Erie Canal" starts with a warning to riders on a barge being towed by a mule,

"Low bridge, everybody down! Low bridge, for we're comin' through a town!"

Low bridges continue to challenge and limit transportation on inland waterways. Recently Hollyhead Towing ( www.holyhead.co.uk ) of North Wales U.K. developed a self powered vessel, the Afon Dyfrdwy, to transport the prefabricated wings for the new Airbus A380 from the manufacturer at Broughton, near Chester, down the River Dee (Afon Dyfrdwy is the proper Welsh name for the River Dee). Components of the aircraft are built at various locations for final assembly at Toulouse, France. After being moved one at a time down the river to Mostyn Dock the 46 x 12-meter 200-ton wings are transhipped on an ocean going vessel for final delivery.

The river trip requires the 57.6x14.8-meter boat to pass under low bridges. To meet these restrictions while transporting its valuable cargo, the boat was built at McTay Marine Ltd. Bromborough, UK. with a 2.8-meter molded hull depth and a sophisticated ballasting system capable of taking the draft down to 1.5 meters with a 4.3-meter air-draft. The ballast system can vary the boat’s trim to allow for differing weight distribution between the port and starboard aircraft wings.

In addition to the ballast system, the boat is equipped with a low level cargo deck with 300 tonne capacity lift system. The allows a specially designed trailer to roll on with the wing. The lift system then raises the wing on its pallet allowing the trailer to be rolled off the vessel and the wing to be lowered to the deck. Heavy steel rails above the bulwarks assure that the wing will not be damaged in the event that the boat did come in contact with an overhead obstruction. At the same time attention is paid to monitoring the river depth and bottom contours with an echo-sounder with an electronic survey and route planning navigation system,

Propulsive power for the boat is provided by two Cummings KTA 19 M3 engines, 477kw each driving a pair of Type W60 Jastram (www.jastram.net ) azimuthing jet thrusters. These take water from the hull sides just at the chine and expel it out the bottom of the boat. Controllable vanes can direct it in any direction. Not only does this give the operator a very high level of control over the vessel’s movement, it also protects the river bottom from the type of disturbance that conventional propellers could create. Environmental requirements stipulate that river silt may not be disturbed and the vessel wake must be kept to less than 30 centimeters in height. The main engine thrusters are located aft. An additional pair of Jastram W20 bow thrusters, each driven by a Cummins 6CTA8.3, give the operator an additional level of control and redundancy. The boat is classed, A1 IWW `Roll on Roll off barge`, LS "0", Zone 1, `River Dee Service`, + LMC UMS, E.P., A, B. UK MCA Class IX A.

The Afon Dyfrdwy was delivered from the shipyard of McTay Marine Limited of Bromborough in the Wirral early in 2004. Following a fitting out and training period, she went into service in April 2004.

For further information please contact:

Richard Payne
Marine Technical Manager
Cummins Engine Company, Ltd.
Royal Oak Way South
Daventry, Northants United Kingdon
NN11 5NU
Phone: +44 1327 886555
E-mail: richard.j.payne@cummins.com

Mr J McBurney
McTay Marine Ltd

The Magazines, Port Causeway,
Bromborough,
Wirral, CH62 4YP
Phone: +44 (0)151 346 1319
Fax: +44 (0)151 334 0041
E-mail: robertmcburney@mctaymarine.com

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