Swimmer injured by unguarded propeller

Lookout! Issue 31, August 2014

A woman was seriously injured when she was struck by a vessel’s propeller while swimming with dolphins.
Maritime New Zealand ©2020
The catamaran used for dolphin watching and swimming did not have propeller guards.

The female tourist was one of 20 passengers on a catamaran built for dolphin watching and swimming. The passengers were given a safety briefing for the vessel shortly after its 8am departure from the wharf.

When the vessel encountered dolphins, there was another safety briefing before swimming. During this briefing, passengers were advised not to enter the water until told to do so by a crew member. They were instructed to sit on the first steps at the stern transom and then ‘sit, slip and slide’ into the water. No advice was given to avoid swimming near the propellers.

The aft deck of the catamaran, with a retractable metal platform to help swimmers board the vessel.
Maritime New Zealand ©2015

The swimmers returned to the vessel from their first swim without mishap. As the vessel approached dolphins at a new location, the crew instructed the passengers intending to swim to gather at the port and starboard aft quarters, and to wait for instructions to enter the water over the sterns of both hulls.

One passenger interviewed later said people were excited and the crew encouraged swimmers to get into the water quickly to make the most of their time with the mammals. The passenger described the situation as ‘frenetic’.

Believing she’d been given the go-ahead, a woman seated on a step on the port aft section of the transom dropped down into the water. However, the master was still positioning the vessel and had the engines in reverse. The port hull slowly reversed over the woman, bringing her into contact with the port propeller.

The vessel’s helm mirror, showing the swimmer disembarkation area.
Maritime New Zealand ©2020

As he soon as he noticed that the woman was no longer sitting on the swim platform ready to enter the water, the master put the engines into neutral. He noticed a series of impacts through the controls, most likely caused by a propeller striking the woman. The master cut the engines immediately and went to the roof of the bridge. Seeing the woman emerge, screaming, at the surface of the water, he jumped in to assist her.

The woman, whose right leg had sustained a deep cut, was helped back on board by the master and another crew member. She said later that she had felt the propeller hit her shoulder and she remembered clawing her way to the surface, fighting against the force of water that was pulling her down. At the time, she believed she was going to lose her leg or bleed to death.

A medical professional on board gave first aid, while the master radioed for an ambulance to meet the vessel at the shore. The injured woman was treated in hospital for a deep laceration to her calf, and for multiple linear abrasions and bruising to her right arm.


  • It was the second serious accident in New Zealand involving a dolphin swim vessel in less than four years and involved a tourist vessel in similar circumstances.
    • MNZ’s investigation resulted in charges being filed against the vessel’s master and operator for breaches of the Health and Safety in Employment (HSE) Act 1992.
    • Under the HSE Act, it is the responsibility of the employer (in this case the owner and operator of the vessel) to identify and manage all hazards for their operation. In this case, the master and operator failed to take all practicable steps to identify and properly manage the hazard of unguarded propellers.
  • The vessel is a 15m twin-engined catamaran with indoor observation decks built for dolphin viewing and swimming. Between the aft hulls is a retractable metal platform to help swimmers board the vessel and keep them clear of the propellers. Beneath the aft hulls twin unguarded propellers protrude relatively closely to where swimmers enter the water from the vessel.
    • Unguarded propellers are a serious hazard to people in the water. Before the accident happened, MNZ ran an industry workshop for commercial swimming operations, which the operator had attended. The workshop dealt with this and other safety issues. The safety points and interim safety guidelines for this kind of operation have been widely circulated in the industry and posted on MNZ’s website.
    • At 1 July 2014, the Maritime Operator Safety System (MOSS) entered into force, with a focus on safety as it applies to an entire operation. New guidelines for commercial swimming operations will be issued later this year.

Practicable steps that could have been taken to address the risks include:

  • procedures to prevent passengers getting onto the swim platform and into the water while the vessel was moving.
  • identifying the hazard of unguarded propellers in the vessel’s SSM manual and having measures to manage it. These include:
    • posting a diagram on board the vessel to show danger areas for swimmers
    • possibly installing a safer drive system (such as jets)
    • creating an area forward of the stern where swimmers could get in and out of the water safely
    • using guards and barriers and ensuring that entry to the water was only from the swim platform and not from outboard of the sponsons
    • using the vessel’s horn or other clear signal to indicate to passengers when it was safe to enter the water
    • auditing the crew to ensure the procedures were being followed.

Had some or all of these measures been taken, there would have been a greatly reduced risk of any person getting into the water while the vessel was moving and coming into contact with the propellers.

  • The master breached the HSE Act as he failed as an employee to take all practicable steps to ensure that no action or inaction by him while at worked caused harm to any other person.
    • Restraints to prevent people coming into contact with moving machine parts or to prevent them from getting into the water at the wrong time must be used as intended. The injured woman said a restraint rail and partition boards to control swimmers’ entry to the water were present but not in use.
    • The master should have ensured these physical barriers were used to prevent swimmers accessing the swim platforms and entering the water while the vessel was manoeuvring. The operator said the guards weren’t in place, to give swimmers faster access to the water. But it said safety procedures had since been improved and passengers were no longer allowed to be on the swim platforms while the vessel was reversing.
  • As well as safety briefings provided to passengers, all other instructions and signals involving the safety of people on board a vessel should be clear and unambiguous.
    • Practicable steps that could be taken include a requirement to give a clear signal (such as sounding the horn or a whistle) to indicate when a swimming vessel has stopped moving and it is safe to enter the water.
    • The master and operator were both convicted and fined under the HSE Act.
  • MNZ is concerned about the number of recent injuries caused by propeller strike. The lessons from this and similar accidents should be heeded and incorporated into operational procedures for vessels involved in swimming operations.

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