Pilot's decision on turn led to Sunshine Bridge strike, NTSB says

Maneuvering upriver first would have provided the tanker Dank Silver with sufficient steerageway

The following is a marine accident brief from the National Transportation Safety Board (NTSB):

(WASHINGTON) — On June 16, 2019, about 1322 local time, the bulk liquid cargo vessel Dank Silver was transiting downbound on the Mississippi River, near Donaldsonville, La., when it struck the fender of the western pier to the main (channel) span of the Sunshine Bridge. No pollution or injuries to the 19 crewmembers on board Dank Silver were reported. Damage to the vessel was about $1 million, and damage to the bridge was estimated at $3.5 million.

Probable cause

‚ÄčThe National Transportation Safety Board determines that the probable cause of the tank vessel Dank Silver’s contact with the Sunshine Bridge was the pilot’s decision to turn the vessel off the dock instead of going upriver to gain sufficient steerageway to maneuver downriver through the bridge.

Analysis excerpt

The VDR recording of the master/pilot exchange did not include a discussion of the pilot’s plan for maneuvering through the bridge, and no subsequent discussion of the ship’s course, other than the bridge team’s confirmation responses to the pilot’s conning orders, were recorded as the vessel neared the bridge. Clear and concise communication is a characteristic of sound bridge resource management, but it is unlikely that input from the master or second mate after getting under way could have averted the contact, given the current and the vessel’s trajectory.

When the pilot ordered the rudder hard to port, thrust from the propeller was stopped, so the ship’s rudder had less effect on turning the ship. At this point, the tanker was essentially drifting in the strong current, as the ship’s speed through water was minimal or negative while its speed over the ground was substantially higher, which was setting it to the right of the pilot’s intended track. It appeared that the pilot never gained control of the ship. The ship’s ECDIS recordings show the tanker toward the right descending (west) bank, rather than the left descending (east) bank, where the bridge’s channel span was. Given the negative or low speeds through the water, using greater propeller thrust earlier would have improved the ship’s response to rudder inputs.

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