|Tugboats attend to Overseas Cleliamar after the tanker lost propulsion near San Francisco in January 2009. The Coast Guard said the ship experienced a valve malfunction after a switch to low-sulfur fuel. (Courtesy U.S. Coast Guard/Petty Officer 3rd Class Pamela J. Manns)|
Since California began requiring ships to switch to low-sulfur fuels within 24 miles of its coastline, some vessels have had problems with engines stalling.
As a result, the U.S. Coast Guard has issued a marine safety alert urging ship operators to be careful when switching fuel at sea. The advisory encourages mariners to consult with equipment manufacturers and fuel suppliers for guidance and to develop changeover procedures and crew training.
“When switching fuel oil, some ships have experienced propulsion losses linked to procedural errors or fuel oil incompatibility,” the Coast Guard said in its November 2009 alert.
After court battles resulted in intermittent enforcement of California’s 2007 regulation, the rules now have been fully in effect since July 2009. All commercial oceangoing vessels more than 400 feet long or larger than 10,000 gross tons must switch to the cleaner fuel as they approach the coast. Since July, at least two vessels per month â€” six in July alone â€” had issues with engines either stalling or maintaining rpm while running on low-sulfur, the Coast Guard said.
The safety alert advises operators to develop detailed fuel switching procedures, including making any required changes to the fuel delivery system. The agency recommended that crews complete the fuel switch well before crossing the 24-mile mark. Crew training needs to be specifically targeted to fuel switching, and the fuel system needs to be on a strict maintenance schedule. All aspects of the fuel system, including seals, gaskets, flanges, fittings, brackets and supports, should be on the schedule. All alarms must be operational.
Intertanko issued its own alert based on a letter from Capt. P.M. Gugg, the captain of the port in San Francisco, urging ship operators to pay extra attention to the fuel switching process and to be proactive in preventing propulsion failure. Gugg said the Coast Guard would require tug escorts for problem vessels.
Some ships encounter difficulty in the changeover process from residual fuel, which is heavy and needs to be heated, to distillate fuels. These are thinner and don’t need heating. If the fuel delivery system isn’t properly cooled, the distillate fuel is vaporized prior to introduction into the injectors. Sputtering and/or stalling may result.
Engine builders recommend changing the temperature by no more than 20 degrees Celsius per minute. A changeover time of approximately 50 minutes is required. This means that captains need to factor the extra time into the beginning or end of a voyage.
“The vast majority of companies have introduced procedures, but we’re seeing mistakes in those procedures,” said Coast Guard District 11 Lt. Cmdr. Kiley Ross.
In January 2009, Overseas Cleliamar from the Marshall Islands lost power while burning low-sulfur fuel as it departed San Francisco. The ship almost grounded at the Marin Headlands. The fuel itself wasn’t to blame.
“They did not lose propulsion because of diesel fuel. They lost propulsion because of valve malfunction and procedural issues,” said Ross.
To reduce air pollution, the U.S. and Canada are developing rules that would require low-sulfur for all oceangoing ships along their coastlines. Ship operators do not want to use the cleaner fuel all the time because it costs about $30,000 more per voyage, Ross said.
The California Ninth Circuit Court of Appeals agreed in December to hear a petition by the Pacific Merchant Shipping Association questioning the state’s authority to enforce its rule. States have traditionally had authority to establish rules that extend only three nm offshore. The organization prefers the U.S. and Canadian effort to enact regulations applying to all of North America.