They're called tractor tugs, and they live up to the name and more. They can slow a supertanker down, and then change its direction while it's still moving. Two of the five on duty in Prince William Sound, Nanuq and Tan'erliq, are even called Prince William Sound class tugs. All five were specifically designed for the Sound and drive on 10,000-plus horsepower provided by twin engines. Their propulsion systems make them as nimble as they are strong. Depending on conditions, they can move in any direction on full power.
These five tugs, together with double hull, double-engine ships and better tracking systems, make the Sound's tanker traffic the safest in the world.
Let's keep it that way.
Tug escorts will no longer be required by law once the entire Alaska tanker fleet is double-hulled, which is likely to happen this year. The double-hull conversion was required by the Oil Pollution Act of 1990, passed by Congress after the 1989 Exxon Valdez oil spill.
At least one oil shipper, BP, supports “a fresh risk assessment” for Prince William Sound. Such a study, which would be led by the Coast Guard, might lend support for a move to dispense with the tug escorts.
Much as Alaska's oil shippers might welcome a chance to cut their costs, the tugs should stay on duty.
Yes, double hulls -- and, just as important, twin tanker engines -- do make an oil spill less likely. The extra hull puts more space and steel between oil and water. The second separate engine and propulsion system mean that one engine can fail and the tanker can still steer away from trouble. Most of the tankers working the Sound now have the two-engine system. That's all to the good.
But double hulls and twin engines don't make a spill impossible, and can't account for the human factor -- the mistakes, misjudgments and oversights that lead to more than 80 percent of marine accidents. And two engines aboard a tanker don't guarantee that both can't fail.
Tractor tugs give Prince William Sound and all the life that depends on it extra insurance against a repeat of the Exxon Valdez disaster. Tractor tugs help the big ships keep an unblinking watch. Tractor tugs keep that vigilance close at hand -- one tug is tethered to the tanker during the passage through the Valdez Narrows. Tractor tugs can both warn a tanker pilot of trouble and do something about it if necessary.
If the worst does happen, the tractor tugs are right there to respond with booms, skimmers and storage for recovered oil. They couldn't soak up a massive spill, but they could help until stronger response arrived.
Keeping the tug escort in the Sound is a cost of doing business in Alaska. The shippers pay, and so do we, because the cost of spill prevention is deductible in calculating state royalties and taxes. That's fair.
Lest anyone be tempted to let down their guard, remember what happened 20 years ago when the Exxon Valdez hit Bligh Reef. Nobody thought that would happen either.
Keep the tugs on the Sound and the oil out of it.
BOTTOM LINE: Percentages and probabilities? We've heard them before. We'll go with 10,000 horses and well-seasoned crews.