Safety issues have been identified with Fullers' emergency procedures after one of its passenger ferries had to be evacuated on the Hauraki Gulf in 2011.
The Jet Raider was making a trip from Auckland to Waiheke Island with five crew and 316 passengers on board on the morning of August 27.
According to a Transport Accident Investigation Commission (TAIC) report, released today, about 11.20am the starboard engine failed catastrophically when two engine connecting rods broke free of the crankshaft and were ejected through the engine casing.
"The escaping mixture of fuel and exhaust gases, and possibly steam resulting from damage to the cooling water system, set off the fire alarms and gave the crew the appearance on the closed-circuit television that a fire had occurred," the report said.
The crew shut down the engines, sealed the engine compartment and released the CO2 fire-suppression system. Meanwhile, the skipper raised the alarm and anchored the ferry in the Motuihe Channel.
The passengers were transferred to another company ferry that had been following close behind. Nobody was injured,.
The subsequent investigation found there had not been a fire but that a momentary "flash-off", caused by the ignition of a vapourised fuel and exhaust gas, might have occurred.
TAIC identified two safety issues: transferring passengers to another vessel as a form of abandoning ship was the usual method employed by ferry operators in the Hauraki Gulf because of the high probability of another passenger vessel being in the vicinity.
However, this method was not considered during emergency response training, and no thought had been given to small modifications in ferry design that could reduce the risk to passengers during such an event.
TAIC also found that when the fire-suppression system was used, only half of the required CO2 gas was released to the engine room.
"Part of the reason was a lack of clear placarding to highlight the differences in procedures between mono-hull ferries with single engine rooms and catamaran-style ferries with split engine rooms."
The report concluded that training for emergency responses should be extended to cover the vessel-to-vessel transfer of passengers when abandoning ship.
It also said that instruction placards for critical systems such as fire-suppression systems should be clear and concise to avoid operators misinterpreting them at times of high or stressful workload.