Overcrowding Near Anchorage During High-Water Conditions Causes Vessel Collision


What happened?

On January 17, 2016, about 1631, the cargo vessel Manizales collided with the bulk carrier Zen-Noh Grain Pegasus on the Mississippi River at mile marker 153, near Hester, Louisiana. Before the collision, the Manizales had anchored in the Belmont Anchorage, an area about 1.1 miles long and 300 feet wide, just upriver from the Zen-Noh Grain Pegasus.

Within 30 minutes of dropping both of its anchors, the cargo vessel’s anchors dragged. The Manizales drifted downriver toward the bulk carrier and became entangled in the larger ship’s port and starboard anchor chains.

Damages to Vessel

The Manizales incurred more than $2.2 million in damage from the collision, and the Zen-Noh Grain Pegasus lost its starboard anchor. No pollution or injuries were reported.

The Stage Setting

The Manizales was transiting downriver with a pilot in control, when he prepared to anchor on the left descending bank. Early 2016 was a period of high water on that section of the Mississippi River, with the increased water volume resulting in a corresponding increase in  the river current.

Consequently, the pilot anchored the vessel as close to the left bank as he could to avoid the main stream of the current. An integrated tug and barge was anchored upstream of the Manizales’s intended position, and two ships were anchored downstream. The Zen-Noh Grain Pegasus was immediately downstream of the Manizales.

Taut Anchor Chains

About 17 minutes after anchoring the Manizales, the pilot noted that the anchor chains had become taut. At this time, the stern of the Manizales was about 500 feet from the bow of the Zen-Noh Grain Pegasus.

Just as the pilot was about to disembark the Manizales, at 1628,

the Manizales’s bow swung into the river. By the time the pilot returned to the bridge, the ship was almost perpendicular to the river. At 1629, the pilot ordered the rudder to starboard and the engine to half-ahead speed.

Inconclusive Investigation Results

However, the pilot told investigators that the engine was not in standby and therefore not available for several minutes to provide the ordered propulsion power. Conversely, the vessel’s chief officer stated that the engine was operating and that he saw propeller wash before the collision. Investigators could not conclusively determine the actual status of the engine at the time of the accident. Regardless, the ship was not able to overcome the force of the river current as its anchors dragged.

The Collision

The propeller of the drifting Manizales eventually caught the starboard anchor chain of the Zen-Noh Grain Pegasus. The entanglement pulled the Manizales’s propeller shaft outward 6 inches, damaging its reduction gears.

Moments later, the Zen-Noh Grain Pegasus’s port chain caught and wrapped around the Manizales’s stern crane, holding the vessel in place as the current pivoted the Manizales around the bow of the bulk carrier. At some point as the ships collided, the bridge wing of the Manizales was torn off.

By 1643, the Zen-Noh Grain Pegasus’s engine was online, and the bulk carrier began to maneuver under power. The pilot on the Manizales told investigators that the bulk carrier was coming ahead, pulling the Manizales and causing it to list. After receiving a call from the Manizales pilot on VHF radio, the Zen-Noh Grain Pegasus master moved his rudder from port to midship and used the engine to prevent the ship from swinging out into the main river channel.

About 1 to 2 minutes later, the Manizales came free of the anchor chain when its crane broke from the deck. Once released from the chain, the Manizales floated free and drifted down the port side of the Zen-Noh Grain Pegasus. The vessel continued to drift downriver until it was corralled by five towing vessels.

New Regulations Enforced

Eleven days before the accident, on January 6, the Coast Guard Captain of the Port for New Orleans had issued a Marine Safety Information Bulletin to address the hazards to anchored vessels, requiring vessels to not only use two anchors but to also keep their propulsion systems on standby.

After the collision, the New Orleans-Baton Rouge Pilots Association, which manages the movement of self propelled commercial vessels when their pilots are on board (including when and where to anchor), decided to limit occupancy in the Belmont Anchorage to one vessel during high-water conditions. Had this strategy been in place when the Manizales anchored, the collision would not have occurred.

Probable Cause

The NTSB determined that the probable cause of the collision between the Manizales and the Zen-Noh Grain Pegasus was the decision by the New Orleans-Baton Rouge Pilots Association to assign the Manizales to the Belmont Anchorage during high-water conditions with three other vessels already anchored in the area.

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Source: NTSB


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