A NAVAL architect is due to begin work in Dublin Bay shortly in a "King Canute" attempt to reduce the large wave generated by Dun Laoghaire's high-speed ferry (HSS).
A similar wave pattern caused by Stena Line's sister ship in Belfast Lough has already been largely resolved by the naval architect, according to Dublin Port. However, it is understood this involves dropping the ferry's high speed to a fraction during the approach up the Lagan mouth.
So serious has the "pressure wave" problem been in Dun Laoghaire that the local authority erected signs in early summer, notifying shorewalkers to beware for up to 20 minutes after the Stena Explorer's arrival.
Following a potentially serious incident at the Irish Lights depot in Dun Laoghaire, when seas were reported to have surged towards its dock where navigational buoys are stored, a technical team was set up. The team involves Dublin Port which has pilotage responsibility for Dun Laoghaire, Stena Line and the Department of the Marine.
During trials, the HSS agreed to halve its speed on the approach from the Burford Bank, a little over three miles off the ferryport.
Stena Line has denied this has contributed to recent delays in the advertised 99-minute voyage between Dun Laoghaire and Holyhead. Lost time was made up at sea, according to a spokeswoman, although the ferry's cruising speed is set by the licensing authorities in Ireland and Britain.
The sub-surface pressure wave is caused by the turbulence of the catamaran, which is the first of its type and can travel at 40 knots. Southside swimmers and small boat owners at Bulloch Harbour in Dalkey had complained of "eight to 12-foot" seas, but there were no reports of accidents, according to the authorities. The so-called "bow wave" could be observed at the harbourmouth some minutes before the craft approached.
The presence of two sandbanks - the Burford and Kish - outside Dublin Bay is expected to make the consultant's task somewhat more complicated than that in Belfast Lough. Wave velocity increases in shallow water; in other words, banks make for rougher seas.
Stena Line said trials involving speed and direction have recorded a "big improvement" in the past two months, and this had been confirmed in a letter to the company from swimmers at Sandycove.
