Tailgater turns turtle


On a cool but calm June evening, a catamaran fast ferry was travelling upstream on the Parramatta River. On its approach to a cross-river car ferry, the master was obliged to bring the catamaran ferry to an emergency stop. The car ferry had made a radio transmission to alert approaching traffic of its crossing, but a fault in the microphone cut the transmission and it was unheard by the catamaran ferry master.

After coming to a stop, the catamaran ferry master placed his vessel’s engines astern and commenced to reverse about 20 metres to ensure that his propellers cleared the cables of the cross river car ferry. In doing so, the stern of the catamaran ferry collided with the bow of a small runabout which had been following close behind in the ferry’s wake. When the master of the runabout noticed the ferry reversing, he too placed his outboard engine astern.

Unfortunately, the runabout’s propeller was unable to get a ‘bite’ in the water due to the cavitation of its propeller. This was caused by the catamaran ferry aerating, or ‘foaming’ the water in its wake. Therefore, the runabout was unable to manoeuvre out of the way of the reversing catamaran ferry. After the initial collision, the runabout capsized, throwing the occupants in the water.

Fortunately, the runabout occupants were not seriously injured, and were able to cling to the upturned hull of their boat until a passing work barge helped them from the water and returned them to shore.

Lessons learned

  1. While it is tempting to ride the smooth water produced astern of a larger vessel, travelling too close does not allow enough time to take evasive action to avoid a collision. Further, the larger vessel may obscure the view of hazards that may lie ahead.
  2. Travelling in the wake of another vessel may also cause propellers of following vessels to cavitate due to the aeration of the water caused by the propellers of the vessel ahead.
  3. Always keep a proper lookout and travel at a safe speed so that there is plenty of time to take any collision avoidance action that may be necessary.
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