Yanmar Powers Up The Reef Rocket


Reef Rocket keeps up its busy schedule with a Yanmar

Operating a commercial ferry out of Cairns demands the highest standards of performance. Yanmar has played a significant role in the success of Reef Rocket, following a repower with a pair of Yanmar 6HYM-WET engines.

Reef Rocket has more than a passing resemblance to the Sydney Rivercat ferries. Built in 1999 at the Norman Wright Shipyard, Reef Rocket was designed along the same lines. The fibreglass hull is 24m loa, has a beam of 6.9m, a draft of 2.1m and displacement of 36 tonnes without passengers.

Operating from the Cairns Marina, Reef Rocket makes three return trips every day to nearby Green Island, around 15 Nm distant. It is a 45 minute run each way and the passenger load is a maximum of 120 passengers.

In the port engine room, the original engine was removed and replaced with a Yanmar 6HYM-WET some time ago. A unique set of circumstances prevented both engines being replaced at the same time.

That was until 2016 when Reef Rocket underwent a major refit. The vessel was re-glazed, repainted with a 2-pack product and generally brought back to pristine condition inside and out.

During the 2016 re-fit, the second Yanmar 6HYM-WET engine was installed into the starboard engine room. Today, the port Yanmar engine has more than 5,000 hours logged while the starboard engine has 800 hours.

“For our business, reliability is the single most essential thing element that we require with our vessels,” said Andrew Rokstad, Maintenance Manager at Big Cat Green Island Reef Cruises.

“We rate our performance in terms of travel time and fuel consumption. The new Yanmar 6HYM-WET engines are giving us great reliability and excellent fuel consumption, just what we are after.”

The Yanmar 6HYM-WET is a purpose built commercially rated marine engine. The engine is a 6 cylinder in-line block which has a displacement of 13.733 litres and an all up weight of 1386 kgs.

The 6HY series is available with 4 power outputs ranging from 500mhp (368kW) to 700mhp (515kW). For the repower of the Reef Rocket the choice was made to use the conservative and heavy duty continuous rating of 500mhp (368kW) @1950rpm, a decision which will no doubt pay dividends in years to come.

This model includes Yanmar’s latest combustion chamber design, named ASSIGN, a system originally pioneered by Yanmar on their large bore, low speed propulsion engines. These engines are IMO Tier 2 compliant, ensuring emissions are exceptionally low, an important consideration when operating on the Great Barrier Reef.

The ASSIGN technology combined with Yanmar’s mechanical fuel system provides commercial operators with excellent fuel economy. The cylinder head is a quad valve design. The Yanmar 6HYM-WET has a long history already in many passenger ferries in both Australia and New Zealand and a well proven reputation of excellent availability in applications like the Reef Rocket that have a demanding 7 days per week schedule.

With a pair of Yanmar 6HYM-WET engines now installed in both sponsons of Reef Rocket, skipper John Thackeray delivered a glowing endorsement of the performance.

“The new Yanmar 6HYM-WET engines have proven to be quieter, smoother in operation, more compact and easier to service,” John Thackery said.

“Typically, our run to Green Island is at 23 knots with the Yanmar engines ticking over at just 1800 rpm. Fuel consumption is a very impressive 70 litres per engine per hour.”

A top speed of 24.5 knots is achieved at wide open throttle. Both engines drive through ZF 360A model transmissions coupled to shafts and fixed pitch propellers. In addition a Yanmar 4TNV84T Diesel Powered Mase Three Phase 25kVa generator set supplied by Power Equipment Pty Ltd is installed in the engine room, generating enough power to drive the entire onboard electrical system.

“Our Yanmar engines have definitely delivered better fuel economy through their superior technology. In addition, we like their long service intervals & the mechanical fuel management system as we simply cannot afford to have any unscheduled downtime.”