“We could not have Chosen a Better Engine than Yanmar”


Bill Coombe is a long standing, well respected commercial operator who powered his new whale watching vessel, Amaroo, with a pair of Yanmar 6HY-WET marine engines. Bill’s endorsement of the Yanmar brand is just as powerful as the 650mhp engines now in the engine room.


“We could not have chosen a better engine than Yanmar”, said Bill Coombe who has operated the Amaroo Cruises business out of Forster for the past 36 years.

“We are very, very happy to have chosen Yanmar,” Coombe said.

“The Yanmar 6HY-WET diesels are so smooth, quiet and vibration free. They start instantly and are devoid of complicated and hard to service electronics. The Yanmar’s are of extra heavy construction but the surprising feature is their fuel economy.”

Following rigorous sea trials, the fuel data since the vessel entered service confirms that under a variety of loads and speeds up to 25 knots, the fuel burn is only 15 litres per engine per hour. For a vessel of the size of Amaroo, the economy according to Bill Coombe is “unbelievable”.

Yanmar’s 6HY-WET model is a purpose built commercial grade marine engine. It includes Yanmar’s latest combustion chamber design, named ASSIGN, a system originally pioneered by Yanmar on their large bore, low speed propulsion engines.

This technology combined with Yanmar’s own mechanical fuel system delivers impressive fuel consumption results and provides commercial operators with excellent fuel savings.

The Yanmar 6HY-WET is the perfect selection for operators who demand the ultimate reliability from their vessel. The cylinder head features a quad valve design for each cylinder. Combined with the twin turbochargers the Yanmar excels in all conditions, whether it be continuous duty application such as a tug boat or an intermittent high fluctuating load as experienced with a passenger ferry or tourist vessel.


Amaroo Cruises enjoys a long standing relationship with Incat Crowther, the Sydney based specialist catamaran designers. The first Incat Crowther design was built for Amaroo in 1981, the second hull followed in 1998 and now the third and current hull is a 2014 build.

Incat Crowther developed Amaroo a full 4m longer than the previous hull, without adding to the already shallow displacement. Amaroo’s daily dolphin and whale watching run presented many design challenges as the trip originates in the shallows of Wallis Lake, before passing under a low bridge and then entering the open ocean.

With Amaroo built by Aluminium Marine in Brisbane, the hull boasts a length overall of 23.9m, a beam of 7.5m and a maximum draft of 0.85m. Propulsion is conventional shaft drives driving through heavy duty ZF500A hydraulic shift down-angle transmissions. This is another area where Bill Coombe elected to ‘oversize’ the equipment to ensure long life and high reliability.

On board Amaroo, the facilities are amongst the best in the business. The superstructure is isolated from the hull on resilient mounts. The isolated deck house ensures exceptional low noise and vibration characteristics.

The vessel is rated to carry 171 passengers. This is spread across 101 passengers inside, 70 seats on the upper deck and additional space for up to 5 wheel chairs. Indeed Amaroo is a ‘next generation’ vessel meeting the latest regulations for access, wheel chair capable lavatories, wide aisles and dedicated priority seats.

Prior to selecting Yanmar to power the new vessel, Bill Coombe spent considerable time with Ray Harris from Power Equipment who explained the benefits and advantages of Yanmar diesel engines. This involved a visit to personally inspect similar Yanmar engines at the Power Equipment Coomera branch office. Bill Coombe then went further and spoke to existing Yanmar customers to assist in his research process.

Once the hull was complete and the engines installed, Bill Coombe was on hand for the sea trials conducted by Power Equipment technicians. He was impressed with the process and attention to detail.

“Sea trials were comprehensive,” Bill recalled.

“Three senior Yanmar representatives attended, each testing and ticking off every engine parameter. They spent many hours making sure everything was perfect, before signing off.”

In sea trials a top speed in excess of 27 knots was achieved. The hull has a service speed of 25 knots. The speed trials both light ship and fully loaded, exceeded the designer’s forecast by 15%. Boat handling is both predictable and easy, with a very low wash.

“We could not have chosen a better engine than Yanmar.”