NTSB finds captain’s incorrect assumption, poor communication caused collision between OSV and coast guard buoy tender

The National Transportation Safety Board (NTSB) found that a captain’s assumption and poor communication led to a collision between an offshore supply vessel (OSV) and a US Coast Guard buoy tender in Sabine Pass, a waterway between Texas and Louisiana, on October 11, 2020.

The NTSB has released Marine Investigation Report 22/04​ detailing its investigation​ into the collision between the OSV Cheramie Bo-Truc No 33 and the US Coast Guard coastal buoy tender Harry Claiborne.

Cheramie Bo Truc No 33 was traveling outbound for sea in Sabine Pass when it collided with Harry Claiborne near Texas Point, Texas, on the said date.

The OSV subsequently ran aground. The crew attempted to refloat the vessel, and as it broke free, the current set it into the stationary buoy tender, resulting in a second collision.

Three crewmembers aboard Harry Claiborne suffered minor injuries.

Damages for the two vessels totaled US$505,951, including US$440,879 in damages to Harry Claiborne and US$65,072 in damages to Cheramie Bo Truc No 33.

Two days prior to the collision, Hurricane Delta impacted the area and caused several buoys in Sabine Pass to move from their assigned locations. At the time of the collision, Harry Claiborne was servicing buoys impacted by the hurricane.

The captain of Cheramie Bo-Truc No 33 called Harry Claiborne by VHF radio requesting to overtake the buoy tender on the latter’s starboard side.

The OSV’s captain told investigators that he “didn’t realise that the buoy was on location” and thereby assumed the coast guard vessel was servicing a buoy that had moved into the channel.

As Cheramie Bo-Truc No 33 was attempting to overtake the buoy tender, the depth sounder quickly dropped, and the captain aborted his attempt to pass in an effort to avoid running aground.

Despite the captain’s efforts, the OSV collided with the buoy tender. Two crewmembers on the coast guard vessel sustained minor injuries.

The OSV then grounded in the mud alongside the channel.

The NTSB report said the crew of Cheramie Bo-Truc No 33 informed the Coast Guard Vessel Traffic Service (VTS) of their plans to refloat the vessel and get underway; however, they did not communicate their plans to the crew of Harry Claiborne.

The OSV’s crew worked for 45 minutes to get the vessel out of the mud. As they attempted to manoeuvre around the buoy tender’s stern, the OSV’s starboard bow struck the other vessel’s starboard quarter.

A coast guard crewmember sustained minor injuries as a result of this second collision.

The NTSB determined the probable cause of the initial collision was the OSV captain’s assumption of the stationary buoy tender’s position, which led to his decision to pass the vessel outside the channel, resulting in a late manoeuvre toward the coast guard vessel to avoid running aground.

The NTSB said that a contributing factor to the collision was the coast guard crew not questioning the passing arrangement proposed by the OSV captain.

Causing a second collision was the lack of coordination and communication between the two vessel operators when Cheramie Bo‑Truc No 33‘s crew refloated their vessel.