The National Transportation Safety Board has released its findings from an investigation into the May 2012 collision between a 750-foot oil tanker and a jackup rig in the Gulf of Mexico just off the coast of Corpus Christi, Texas.
On May 2, 2012, at 0718, the oil tanker FR8 Pride collided with the mobile offshore drilling unit (MODU) Rowan EXL I in Aransas Pass, Corpus Christi, Texas. No one was injured in the collision, but the two vessels sustained an estimated $16–17 million in damage.
In its report, the NTSB said it has determined that the probable cause of the collision was the failure of the FR8 Pride’s main propulsion engine, which resulted in reduced maneuverability of the ship.
A Coast Guard update following the collision indicated the FR8 Pride was heading inbound in the Aransas Pass Channel when it reportedly lost propulsion and drifted into the Rowan EXL-1. The NTSB report elaborates:
Earlier that morning, the 750-foot-long double-hulled oil tanker FR8 Pride got under way from an offshore fairway anchorage, inbound to Corpus Christi. At 0704, about 14 minutes before the collision, a local pilot boarded the FR8 Pride to take the ship into port. At 0714, as the FR8 Pride was increasing to full-ahead speed on a northwesterly course in the Aransas Pass channel, the ship’s main propulsion engine suddenly slowed down significantly. The slowdown was automatically triggered by the main engine’s electronic control system in order to protect the engine from damage. As a result of the engine slowdown, the FR8 Pride’s steering ability was greatly reduced, and the ship began an unintended swing to starboard, causing it to sheer out of the channel. Meanwhile, the MODU Rowan EXL I, also inbound to Corpus Christi, was about 400 feet outside the channel, on the starboard side and ahead of the approaching FR8 Pride. The non-self-propelled Rowan EXL I was being towed at 1 to 2 knots by three tugboats at its bow. As the FR8 Pride began to swing to starboard, the FR8 Pride pilot ordered hard starboard rudder in an attempt to make the ship’s bow pass astern of the Rowan EXL I. However, at 0718, about 4 minutes after the engine slowdown began, the starboard-side bow of the FR8 Pride collided with the port side of the Rowan EXL I at about 8 knots. Shortly after the collision, which punctured the FR8 Pride’s hull below the waterline, the ship’s forepeak tank flooded and the vessel grounded at its bow.
The reason for the automatic slowdown of the FR8 Pride’s engine was that the cooling jacket on the engine’s cylinder No. 5 had suddenly cracked. Jacket water began leaking from the cracked cooling jacket, and the main engine control system (Kongsberg AutoChief 4)—detecting the resulting pressure loss in the jacket water cooling system—protected the engine by reducing its speed. FULL REPORT