A segmented, self-propelled barge ran aground along Alaska’s North Slope after its aft decking split from the rest of the vessel and dropped to the seabed.
The 140-foot uninspected landing craft Stryker broke apart Sept. 14, 2010, inside barrier islands of the Beaufort Sea, 40 miles west of Prudhoe Bay, the U.S. Coast Guard said. The vessel was carrying oil exploration equipment including a vacuum truck and empty flatbed trailers.
|The segmented landing craft Stryker lies with its stern aground in Alaska’s Beaufort Sea. A structural failure caused the barge’s aft end to disconnect and fall to the seabed. (Photo courtesy Alaska Department of Environmental Conservation)|
The roll-on, roll-off vessel consists of an assembly of about 20 Flexifloat segments. The emergency, which occurred in nine feet of water, involved an area of the deck that contains the propulsion systems and crew areas. That section remained tenuously attached to â€” but was not supported by â€” the rest of the vessel and could not float on its own.
Stryker was built in 1970 and can be taken apart and trucked around Alaska. Its owner is Bowhead Transport Co., a subsidiary of Barrow-based Ukpeagvik Inupiat Corp. Bowhead’s general manager, Jim Dwight, said he suspects that the accident was caused by a combination of long-term wear and tear and the heavy weather encountered on that voyage.
“It didn’t ground out first. It had a structure failure first,” Dwight said. “It was fatigue and a failure of the pins and surrounding plates due to stress. The top pins parted, and the aft part of the barge â€” where the wheelhouse and engine room and propulsion system are â€” hinged down and it just grounded out.”
Stryker was on a voyage from Oooguruk Island to Oliktok Point, carrying equipment for Pioneer Natural Resources. The trouble happened at 1155 in the lee of Thetis Island, British Columbia, about 60 miles east of Harrison Bay. There were no injuries and the cargo was not damaged. A small amount of spilled fuel caused a light sheen.
Ensign Benjamin Bauman, the Coast Guard’s investigating officer, said an easterly wind was gusting to 30 knots, and seas were three to five feet. The landing craft draws about seven feet of water.
Alaska Clean Seas, two Crowley tugboats and a crane barge responded to the grounding. After the aft tanks were pumped, the tugboats were able to beach Stryker at Oliktok Point on Sept. 21. Two Coast Guard investigators surveyed the damaged vessel.
Stryker, equipped with a ramp, was made of two sizes of Flexifloats: 40 by 10 feet, and 20 by 10 feet. They create a vessel that is 140 feet long with a 40-foot beam.
“There is a large steel pin-like structure that has a notch at each end. The barges are mated together using these pins,” Bauman said. “They are staggered in such a way that you don’t have one single joint running along the entire length of the vessel.”
Bauman confirmed that the vessel’s aft decking was damaged, but he didn’t know the cause. The investigation was continuing in November.
“That was where the most substantial damage was â€” along that forward edge of the wheelhouse,” he said. “Some of the materials that composed the vessel have been sent off to metallurgists.”
Stryker‘s maximum cargo capacity was 350 tons. Dwight said it usually carried only about 200 to 250 tons. At the time of the accident, the load was less than 100 tons.
After the damaged vessel was inspected on the beach, it was dismantled and trucked to Deadhorse, Alaska. Stryker probably will never sail again in its traditional form.
“The barge itself may have a useful life elsewhere, but not in this environment,” Dwight said.