The MAIB has issued a report on its investigation of the powerboat Awesome accident near Little Thatch Island, British Virgin Islands on 2 October 2022, where the loss of control resulted in two fatalities.
On 2 October 2022, the mono-hulled offshore powerboat Awesome was returning to its home port when it unexpectedly veered to starboard, then rolled violently to port, ejecting 10 occupants. Awesome ended up in a vertical position, with its bow in the air, briefly staying afloat before it started to sink by the stern. Two of the occupants did not survive the accident.
From witness testimony and expert analysis, it is probable that Awesome was travelling at about 60 mph when the port drive shaft universal joint failed, the flailing shaft then severed a steering system hydraulic pressure hose. This resulted in a loss of pressure in the steering system, which allowed both stern drive units to snap over to full starboard lock while Awesome was still travelling at about 60 mph.
Failure mechanism
In general, Awesome appeared well maintained at the time of the post-accident inspection. Much of the boat’s routine maintenance was completed by the owner; however, they had no knowledge or awareness that the drive shaft universal joints required regular greasing maintenance. It is likely that the degradation of the port drive shaft yokes and trunnions started before the owner purchased Awesome and that further degradation had occurred during their ownership.
When inspected, all the universal joint trunnions showed signs of overheating, wear and corrosion to varying degrees. As number three trunnion on the port drive shaft started to wear and the running clearance within the bearing housing increased, there would be a cyclic impact loading with the trunnion hitting the bearings with every rotation of the shaft. With further use, the bearing would have disintegrated, and the trunnion would have then impacted on the cast steel yoke of the joint. This repeated impact led to plastic deformation of the trunnion and the degradation of the cast steel yoke, gradually reducing its cross-sectional area. On the day of the accident the cross-sectional area of the yoke had reduced to a level where it could no longer transmit the torque applied by the engine and it failed due to brittle fracture. With the yoke no longer holding the trunnion in place, the opposite trunnion was released from its bearing and the two halves of the universal joint violently separated while rotating at around 1500 revolutions per minute. The end of the drive shaft, still attached to the gearbox, was free to flail around and impacted the steering hydraulic hose
located nearby, severing it.
The key safety issues identified in the report were:
– Steering control was lost when a drive shaft failed and severed a hydraulic pipe feeding the steering system. The mechanical failure of a drive shaft occurred due to a lack of maintenance.
– The kill cords designed to stop the engines in an emergency were not being used.
– Both of the victims drowned. It is likely that they were both rendered unconscious during the accident, neither was wearing a PFD.
– Awesome had seating for five people; at the time of the accident there were 11 people on board, including four children.
MAIB Report conclusions
– Awesome unexpectedly turned to starboard because of a loss of steering control.
– Steering control was lost when a universal joint on the drive shaft from the port engine failed and the flailing drive shaft severed a steering system hydraulic pressure hose, resulting in a total loss of pressure in the steering system.
– The drive shaft coupling failed because it had become worn over a significant period of time due to a lack of routine lubrication.
– Awesome forcibly ejected ten of the eleven occupants because the hull lost its grip on the water when it veered sharply to starboard at high speed, which induced a lateral slide that arrested abruptly as the keel gripped the water triggering a violent roll.
– Kristal Black drowned because she became trapped in the forward cabin as Awesome sank. She was probably already unconscious as a result of impacting the back of the seat in front of where she
was sitting.
– Brianna Graham drowned because she was not wearing a PFD that could have kept her head above water. She was most likely unconscious when she entered the water after her head impacted Awesome’s dashboard during the accident.
– The swift action of the local fishing vessel skipper, charter boat captain and other boats that quickly arrived on scene likely prevented further loss of lives.
– The other injured occupants were fortunate to survive given that none were wearing PFDs and many could not swim proficiently.
– Awesome was equipped with cockpit seating for five people. With eleven people in the cockpit, and insufficient seating for all occupants, the boat was being operated unsafely.
– The accident required a combination of the loss of drive to the port propeller and the loss of steering control. Had only one or other occurred, or had the hydraulic steering system been fitted with a failsafe system, it is likely the outcome would have been much less severe.
Download the report: Awesome Report
