The Observer, September 2004

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Council concerned over tow line breaks

The citizens’ council spent much of the past summer attempting to understand and correct problems that led to two broken tether lines on the rescue tugs that escort oil-laden tankers out of Prince William Sound. The effort has involved not only the council, but Alyeska Pipeline, the Alaska Department of Environmental Conservation, and other companies and organizations involved in keeping the Sound safe from oil spills.

The most recent break occurred during a June 23 practice exercise in calm weather. The first occurred in December 2003, during an exercise in more severe weather. Both involved the Aware, one of three Prevention/Response Tugs (or PRTs) in the Alyeska fleet operated by Crowley Marine Services.

The tether lines – high-strength hawsers 10 inches in circumference –
are crucial to Alyeska’s capability to rescue a disabled tanker.

“In the worst case, a break like this during an actual rescue in heavy weather could lead to another disaster like the Exxon Valdez,” said John Devens, executive director of the council. “It’s clearly a matter that needs to be high on everyone’s priority list.”

In both cases, the breaks appear to have been precipitated by the line burying itself in wraps lower on the winch drum as it came under load during the exercises.
Samson Rope Technologies, manufacturer of the parted lines, analyzed the broken line from the June 23 incident and concluded, “Rope compression, heat and excess chafing appear to be the major contributors to the line failure.”

Because of the dual failures, the state Department of Environmental Conservation has banned the PRTs from serving as primary escorts for loaded tankers. Each tanker traveling through Prince William Sound is escorted by two escort tugs. One – the primary tug – is actually tethered to the tanker for part of the trip to enable immediate response in case of an emergency. Until the problem with the PRTs is resolved, only Alyeska’s Enhanced Tractor Tugs, the Nanuq and the Tan’erliq, are being allowed to serve as primary escorts. Neither of those vessels has experienced tether line problems during exercises.

The council and the other organizations working on the issue came to believe the fundamental issue was a failure to properly rewind the lines onto the winch, and Crowley issued a directive in January of this year, shortly after the December break, directing its captains to “ensure that the tether lines are spooled tight on the winch drums.”

Despite this directive, the second tether line break came in June, leading to the state’s ban on use of the PRTs as primary escorts, and a July 23 letter of concern from the council about Crowley’s handling of the lines.

“We are alarmed by what appears to be a pattern of incidents precipitated by inadequate or poorly understood Standard Operating Procedures (SOPs) and failure to adhere to SOPs by senior operations personnel,” Devens wrote.

As the Observer went to press, the PRTs were still banned from service as primary escorts, though the state of Alaska was expected to lift the ban once SERVS and Crowley were able to demonstrate the line management problems on the tugs have been resolved.

Devens’ letter invited representatives of Crowley and of the tanker companies to address the council on the steps being taken to resolve the problems, and they were scheduled to do so at the council’s September board meeting in Kenai.