Two recent reports over the past few months, one a grounding the other collision and both with vessels under pilot’s advice, serve as useful lessons regarding hydrodynamic effects and vessel safety even when an expert is aboard.
In the case of Arklow Raider, she grounded as she passed the bar at the mouth of the River Boyne, Eire.
The Marine Casualty Investigation Board report says: “As the vessel approached the river bar, its speed was reportedly reduced. The data from the port’s VTMS gave a speed over the ground of approximately 5.4
knots between the Green and Bull light marks. The speed was 5.1 knots as the vessel passed Aleria light. The speed then dropped to 4.9
knots. At 19:30 hrs. the course was 053°T at 4.3 knots.
“The predicted time of high water was 19:54 hrs., the grounding occurred 20 minutes before the predicted high water. At 19:34 hrs. the vessel would not respond to rudder commands. The Master used both engine and bow thruster in an attempt to resume the correct course. At 19:35 hrs. the vessel touched bottom, veered to port and ran aground”.