Slick idea

Another oil spill, another knee-jerk reaction. The Spanish government, rightly or wrongly, acted swiftly and decisively in the wake of the pollution caused by the tanker Prestige to its coastline by banning ageing single hull ships carrying heavy fuel oil from its ports. The EU has also reacted and plans similar measures across the Union.

This action will, without question, reduce pollution risk as age and structural failure have a proven close correlation. However, the policy fails to eliminate risk altogether. As another recent casualty, the sinking of the car carrier Tricolor in the English Channel, demonstrates, structural failure brought about by age is not the only potential cause of a shipping casualty. Collisions and other navigational errors can and will still occur.

Pollution from ships remains a threat regardless of government attempts to dictate the quality of the ships calling at their ports. Curing spills as well as preventing them requires consideration.

Designers at Chantiers de L?Atlantique, the French construction yard of Alstom?s marine division, have recently tackled this consideration. They have developed and model tested a stand-by ship whose principal role would be to respond to oil spills and prevent pollution from reaching shore once it occurs.

The Oil Sea Harvester is a 120m high-speed trimaran. Water lying in the protected area between the trimaran?s slender central hull and its two lateral hulls stabilises the ship allowing it to operate in force 7 winds and 8m waves, says Alstom, while collecting, storing and treating an oil slick.

The ship will be equipped with modular cyclones, pumps, water wheels or scoops to collect surface oil. A heating or chemical plant on the ship will remove water from the oil.

The Oil Sea Harvester will be able to collect and store up to 6,000t of oil before returning to port, says Alstom. If the spill is larger, the ship is equipped to spread dispersants on the surface of the sea to help break down remaining hydrocarbons.

Governments are not averse to investing in hardware designed to respond to emergencies. The UK?s Maritime & Coastguard Agency (MCA), for example, has four vessels on charter from Klyne Tugs, including Anglian Princess (see The Motor Ship, December 2002), to provide emergency support to shipping in UK and, if needed, French waters. The MCA has an emergency response action plan that involves maintaining stores of oil clean-up and pollution prevention equipment at strategic locations around the country with which it can equip these or other contracted in vessels in event of a disaster.

Specific incidents have generated requirements for vessels equipped to respond to oil spills too. Since the Exxon Valdez case in 1989, for example, US authorities have operated the Ship Escort Response Vessels System (SERVS) for laden tankers transiting Prince William Sound. This involves two vessels escorting tankers through the Sound, one of which is specially-equipped to contain and clean-up any oil spill.

The Prestige incident was almost as powerful in its highlighting of an inability to respond to contain a spill once it happens as it was in its highlighting of the root cause of the spill itself. Banning single hull tankers from entering port demonstrates that commercial considerations and therefore money are no obstacle to the prevention of pollution. By the same measure it can be argued that money should be no obstacle to the prevention of pollution once a spill occurs.

The Alstom proposal may prove to be a ship that is too radical and too inflexible for most Coast Guard needs. However, a lot of the thinking is in the right direction, especially if some of the design elements can be combined with other emergency response functions. In particular, the proposal comes at a time when certain governments may view the cost of building and maintaining such a ship as a worthwhile investment in further preventing pollution risk.