The bulk carrier Star of Abu Dhabi was anchored using two anchors on the Lower Mississippi River near Gramercy, Louisiana. The vessel’s port anchor chain parted and the starboard anchor began to drag.
When did it happen?
In the early morning on March 25, 2016, the bulk carrier Star of Abu Dhabi was anchored using two anchors on the Lower Mississippi River near Gramercy, Louisiana. About 0230, the vessel’s port anchor chain parted and the starboard anchor began to drag. As the Star of Abu Dhabi moved with the current, it allided with a Louisiana Sugar Refinery unloading dock and continued to drift downstream. The vessel’s propulsion engine was started, allowing the crew to bring the bulk carrier under control.
What were the damages?
The Star of Abu Dhabi sustained $232,210 in damage to its hull above the waterline; the dock’s damage totaled $4.6 million. No injuries or pollution resulted from the accident.
Rising water levels
The water level of the Mississippi River had been on the rise, and on March 21, the river crested at less than 2 feet below flood stage. Anticipating strong currents, the Coast Guard had required that “unless moored to a shoreside facility or mooring buoys, all deep draft vessels must have three means to hold the position. An example would be two fully operational anchors and the propulsion system in standby.”
Were the suggested precautions taken?
The fully-loaded bulk carrier had anchored in the Lower Grandview Anchorage the prior evening, and at 2154 the master issued a standard “finished with engines” order; informing the engine room that the vessel had completed maneuvering and that the engine and associated equipment could be shut down. The local pilot who was on board at the time did not specifically comment on the engine’s readiness but did instruct the master to maintain a good anchor watch and to contact VTS if there were any problems such as dragging anchors. The pilot then departed the vessel shortly after 2200.
Starboard anchor dragged
Sometime between 0228 and 0230 on March 25, the port anchor chain parted and the bulk carrier began dragging the starboard anchor. As the ship drifted downriver, its speed over ground increased, eventually reaching 3.9 knots. The master directed the engine crew to bring the slow-speed diesel propulsion engine on line, however, this normally takes several minutes.
Vessel brought under control post allision
About 0240, the bulk carrier’s starboard side allided with the Louisiana Sugar Refinery unloading dock. After the allision, the Star of Abu Dhabi continued to drift in the current.
Finally, at 0247, the propulsion engine responded to a dead-slow-ahead command, and the vessel was brought under control about 0.1 miles from the Veterans Memorial Bridge.
Where was the problem?
When the vessel had anchored on March 24, the pilot had directed that each anchor is dropped with four shots of chain (about 385 feet) in the water. The crew correctly did so, but then dropped the starboard anchor with four shots on deck (about 345 feet). The scope of the port anchor chain was, therefore, longer than the starboard chain.
Use of a second anchor was intended to minimize the back and forth motion of the bow, and the scope should have been adjusted to equalize tension on both anchors. A jerking motion or shock load can break a chain, whereas a constant load is less likely to cause a break. Given the longer scope of chain and the current’s effect on the port bow, the port anchor chain was likely taking the majority of the strain.
What other precautionary measures were needed?
The chief engineer told investigators that if the engine had been ordered to be in standby mode after anchoring (as opposed to shutting down, which it was leading up to the accident), a licensed engineering officer would have been stationed in the engine room and the engine would have been available for immediate use.
Probable Cause
The NTSB determined that the probable cause of the allision of the Star of Abu Dhabi with the Louisiana Sugar Refinery unloading dock was the failure of the master to ensure the ship’s propulsion engine was ready to maneuver while the vessel was anchored in a river with high-water conditions.
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Source: National Transportation Safety Board
