Last updated: 12 Feb 2024 | 35 Views |
A pair of Yanmar 6AYE-GT engines have helped a new Aluminium Marine-built fast cat shine in sea trials that have again proven why these new electronically-controlled engines are getting praise from the astute commercial operators who choose them.
An Incat Crowther 29-metre fast cat design, Happy Hour is destined for the Bahamas Ferries Group when it is eventually shipped from Australia to its new Caribbean home.
Power Equipment’s Queensland Sales Engineer Ray Harris worked closely with Aluminium Marine again on this project and has taken particular pride in being able to provide a full power system for the build – including the Yanmar main engines, Yanmar transmissions, Yanmar VC10 electronic control systems and the onboard diesel generators.
The Yanmar propulsion of Happy Hour was a firm insistence of the new owners following their fault-free experience with the same engines in a vessel they took ownership of a year earlier.
Managing director of Aluminium Marine Steve Cordingley explained:
“The Bahamas Ferries Group purchased one of our vessels from another owner and that vessel has performed faultlessly with the electronic Yanmars. In fact, we were the first boat builder in Australia to put these new electronic 1,002mhp Yanmars in one of our ferry builds a couple of years ago.”
Steve says Happy Hour passed its on-water tests with “flying colours!”
“The engines did everything we asked them to do,” Steve said. “We loaded the vessel up with 25 tonnes, (to simulate a full loading), to see if we could maintain good service speeds through the rpm range of the Yanmars. We kept maximum rpms easily, backpressures and exhaust pressures were perfect and we only lost 0.7 of a knot between lightship to a simulated fully loaded vessel.”
The 20.38litre Yanmar 6AYE-GT (S rating) delivers a crisp 737kW (1,002mhp) @ 2000rpm and the Happy Hour build was coupled with Yanmar’s YXH240 gearboxes with a 2.27:1 ratio.
But horsepower numbers and bore/stroke measurements, (155mm X 180mm), in this 6in-line, long-stroking turbocharged engine tell only part of the story. The in-line configuration of this purpose-built marine engine helps for better fitting options, (particularly in catamaran hulls), and allows for good servicing access right around the engine.
These new Yanmars are more than just responsive power on demand and a good fit though.
The 6AYE-GT electronic fuel management difference.
The electronic fuel management is so good on these engines, startup and even hard acceleration is virtually smokeless.
That’s thanks to fuel injection pressure mapping that adjusts accordingly – including
for startup or operational running – so this engine literally adjusts its fuel injection pattern to suit what is being asked of it in operation and even its warm-up regime. Proof of how much improvement comes from such fuel management is evident in significantly lower CO2 and NOX emissions, but shines in power and efficiency.
“We had expectations of around a 200litres per hour per engine at full throttle,” said Steve Cordingley “but actual burn was around 182-184litres per hour per engine, so that is a nice saving over a full year of work as you can imagine.
“When we pulled those engines back to more like normal cruise revs that consumption came back to 137 litres per hour yet still maintained the vessel speed in excess of 22knots. So yes, you could say we’re more than happy. The owner’s representatives were also onboard – they gave the tick of approval too.”
Considering Happy Hour is 61.8 tonnes lightship, and around 90 tonnes fully loaded, that kind of efficiency is no small feat. Good hull design helps of course, (Steve explains that a tunnel design in this particular build has also helped deliver only a 1.4metre draft at lightship “so it will be good in a lot of operational areas”).
But the superb torque-rise characteristics of the Yanmars help give performance under load – and this is not surprising given the 6AYE-GT’s torque output peaks hit at around the 1,200rpm mark. This means that Happy Hour has engines with plenty in reserve that deliver stable cruising speeds, even with load changes or differing sea conditions. Noise is significantly improved with electronic fuel control, with tests showing around two-thirds of noise output to comparable mechanically-controlled engines at 1,000rpm and less than half the combustion noise at lower revs.
To compliment the Yanmar engine electronic management system and to help provide a seamless one stop service and support network for the
client Yanmar VC10 electronic controls and VC10 engine monitoring system were also specified.
This totally integrated Yanmar system helps to ensure excellent operational and monitoring ability of the 6AYE-GT’s at the main helm position and both wing stations. In addition, this system was also packaged to include engine room instrumentation and engine room start/stop functions to facilitate servicing and engine monitoring.
Mase completes a full power package
Complimenting the Yanmar propulsion system in the engine rooms of Happy Hour are a pair of Mase 61T John Deere-powered open frame generators.
These 1,800rpm governed 60Hz generators are powered by the latest generation of heat exchanger-cooled John Deere 4045TFM85 engines that deliver clean, high-pressure common rail diesel power with an impressive USA EPA Tier III emissions rating.
The Mase 61T’s are configured for both main helm and engine room monitoring and are rated to 55 kVA continuous power (61 kVA max).
In all, it adds up to an engine package that is a perfect match for operations like that of the Bahamas Ferries Group where emission compliance and low operating costs are essential.
Aluminium Marine’s Steve Cordingley is certainly happy with the combination of his experienced building and the Yanmar 6AYE-GT’s and Mase 61T’s: “They are getting good fuel consumption with these engines and they are very smooth and quieter underway – it’s a great match,” Steve said.
In Happy Hour’s case, we’ll drink to that Steve!