MO-2008-207 Commercial jet boat Kawarau Jet No. 6, roll-over, Confluence of the Kawarau and Shotover Rivers, 25 September 2008

At about 1400 on 25 September 2008, a tour group of 22 non-English speaking overseas tourists, with a driver, departed the Queenstown Main Town Pier on what was intended to be a typical one hour jet boat excursion on the Shotover River. During the return journey the jet boat touched a sand bar at the meeting of the Shotover and Kawarau Rivers and rolled over coming to rest upside down. One passenger was trapped and drowned under the upturned boat, one other passenger suffered moderate injuries, while five other passengers suffered minor injuries. The boat received superficial damage.
Boats often travelled across the bar when enough water was available to do so. The experienced driver of the accident craft had done so on 2 trips earlier the same day, and the practice was taught during driver training. As the driver approached the bar he saw what he thought was clear water ahead of the boat but as he adjusted his helm to turn the boat upstream the bar appeared in front of the boat. The boat touched the bar as it was in a sliding turn to the right with the momentum causing it to flip and came to rest upside down.
Another jet boat travelling up stream parallel and close to the sand bar at the confluence had crossed ahead of the accident boat. It is highly likely that interaction between the hull of the passing jet boat and the river bank caused the water over the sand bar to recede into the main channel. This effect had not been considered in safety planning or driver training.
The passenger who remained trapped and undetected under the upturned hull highly likely drowned before rescuers could reasonably determine that one was missing. There was sufficient space beneath the upturned boat created by the roll bar for the driver and passengers to escape. Reasons for the deceased not escaping could have been entrapment, disorientation, inhalation of water owing to gasping reflex, flotation from lifejacket forcing the passenger up under the hull, or a combination of these.
The operator has made a number of operating changes to reduce the risk of a recurrence including no longer crossing the bar involved, and requiring drivers to steer straight on to any bars or banks that cannot be avoided to minimise the risk of flipping or rolling over.
Safety recommendations have been made to the Director of Maritime New Zealand to address a number of safety factors identified during the investigation that did not contribute to this accident or its outcome. These recommendations were to: address the coverage limitations of emergency back-up radios bring to the attention of the reviewers of adventure tourism in New Zealand the lessons learned from this accident, and in particular, how to deal with informing potential commercial jet boat passengers of the risks inherent in the activity address with the commercial jet boat industry: the issue of delivering meaningful pre-trip safety briefings to passengers, particularly where understanding of the English language is an issue. the issue of accounting for passengers when multiple boats are involved during emergency response.
(Note: this executive summary condenses content to highlight key points to readers and does so in simpler English and with less technical precision than the remainder of the report to ensure its accessibility to a non-expert reader. Expert readers should refer to and rely on the body of the full report.)