The oil tanker Riverside allided with a loading dock after a failed maneuver during its attempted exit of Corpus Christi Bay.

An allision occurs when a vessel in navigation strikes a stationary object, like a dock or a bridge. In the maritime world, allisions differ from collisions in that collisions involve two vessels striking each other. Except in limited circumstances, such as where the fixed object impedes navigation, longstanding judicial precedence applies a presumption of negligence against the vessel in allisions. This presumption is called the Oregon Rule and is explained by the Fifth Circuit this way: “The presumption presupposes that had the vessel not been mismanaged, the accident would not have occurred.”

Given the presumption of negligence, vessel owners and operators must sort out the root cause of any allision and take care in preventing future incidents to limit potential liability. The National Transportation and Safety Board’s investigation into an allision involving the vessel Riverside provides an interesting example of how the NTSB assigns blame and how fine the line often is between mechanical and human failure.

On March 15, 2021 at 1302 local time, Riverside, an 820-foot-long oil tanker was outbound from Corpus Christi Bay to Lisbon, Portugal laden with 717,554 barrels of crude oil. Due to the vessel’s size, two pilots were required for the transit through the Corpus Christi Ship Channel. The first pilot, Captain Ben Watson directed Riverside from the Epic oil dock through the Harbor Bridge. After an uneventful transit under the Harbor Bridge, the second pilot, Captain Justin Anderson, took the conn for the remaining transit to open water.

As they approached beacons 55/56, Captain Anderson radioed the pilot of Nordic Aquarius, which was preparing to depart from Moda Ingleside Energy Center dock number 4, roughly four miles in front of Riverside’s current position. After discussion, Captain Anderson agreed to let the Nordic Aquarius enter the channel in front of Riverside. To provide Nordic Aquarius sufficient space to maneuver into the channel, Captain Anderson began ordering Riverside to reduce speed around beacons 49/50.

[NOAA Chart NOAA Chart – 11309_Public]

By beacons 43/44, Riverside was progressing at dead slow ahead. Unfortunately, as the vessel slowed, the rudder became ineffective, causing the helm to lose control and Riverside to drift off course. To regain control, Captain Anderson briefly increased speed to slow ahead as Riverside began approaching the port channel bend just east of beacons 43/44. Satisfied that they had reestablished course, Captain Anderson again ordered dead slow ahead to keep speed down and provide Nordic Aquarius adequate maneuvering room. As Nordic Aquarius continued its entry into the channel, Captain Anderson realized Riverside was still approaching too quickly and ordered the engine stopped.

Having now slowed Riverside to 6 or 7 knots and given Nordic Aquarius time to clear the channel, Captain Anderson again ordered dead slow ahead to ensure effective steering through the approaching channel bend. Unfortunately, the engine failed to start. As recounted by Captain Anderson:

I noticed that the helmsman has been holding 25° starboard rudder with no effect. I ordered hard starboard. At that point, we have not yet received the dead slow engine command. I noticed the captain playing with the engine controls and asked him if we had a problem. He informed me that we had lost the main engine.

Having lost propulsion, Riverside was unable to correct course and continued to veer toward Moda dock 4. Captain Anderson immediately radioed nearby tugboats that had just finished assisting Nordic Aquarius depart the dock. One tug remaining on scene attempted to push Riverside’s port bow off of Moda dock 4. Unfortunately, the single tug was not able to redirect Riverside back into the channel before it had to bail out in order to avoid being pinched between Riverside and the dock.

[NTSB Report graphic showing phases of the incident Contact of Tanker Riverside with Moda Ingleside Energy Center No. 4 Loading Dock (]

With no engine, no steering, and no available tug assist, Riverside’s port bow hit Moda dock 4. Moda’s Operations Manager initially reported that Riverside struck “the first end of the finger pier causing approximately 50’ of the pier to break off, including the dolphins [and] lighting.” NTSB’s estimate placed property damage at roughly $7,000,000.

Riverside sustained damage to her port fore peak tank, water ballast tank, and void fore space. Fortunately, despite the heavy deformation noted by the surveyor, no cracks were observed and there was no threat of pollution from the oil on board. According to NTSB’s estimate, Riverside’s damage amounted to roughly $550,000.

[NTSB Report damage photos citing USCG as source Contact of Tanker Riverside with Moda Ingleside Energy Center No. 4 Loading Dock (]

NTSB investigated the incident and determined that the engine failure was caused by a dirty “air start actuator valve within the starting air distributor.” Further investigation revealed that Riverside’s engineers had trouble starting the main engine on March 12—just days prior—as they awaited permission to enter Corpus Christi Bay.  Neither the Coast Guard nor the pilot navigating Riverside on March 12 were informed of the engine start failure and Riverside proceeded to the Epic oil dock assuming any problem was repaired.

Despite initial trouble starting the engine on March 12, the captain and crew onboard Riverside did not believe there was a long-term issue. In fact, the engine was stopped and started twice without incident while maneuvering to the Epic oil dock. However, NTSB’s investigation determined that what Riverside’s engineers believed to be the solution to their problem (introducing more fuel into the engine at start-up) actually had no effect on the system. Instead, whether the engine would start despite the stuck air valve depended on where the valve was in the starting sequence. If the stuck valve was late in the sequence as the engine turned over, sufficient air would already have been introduced to permit the engine to start.

Though Riverside’s engineers believed they had come up with a solution, they entirely failed to accurately determine the problem’s root cause: the stuck valve. Although the inability to start the engine aboard Riverside was traced to the stuck valve—a mechanical problem—NTSB’s probable cause statement ultimately blames the “ineffective evaluation and incorrect solution for a main engine start issue,” putting human error once again front and center in a marine incident report.

Considering the legal presumption of negligence against the alliding vessel and the NTSB’s findings assigning blame to a vessel’s crew, owners and operators are advised to be vigilant when it comes to vessel maintenance and crew training. This vigilance becomes all the more important when a vessel is operating inshore or nearshore under its own power.