The notion of a high speed thrill ride for tourists on the glitzy Gold Coast used to be the exclusive domain of high powered, big revving V-8 petrol engines. Thanks to Yanmar 6LY2A-STP diesel engines, the stereotype has been smashed.
Ocean Jet is different to most companies operating in the thrill a minute jetboat ride business. For a start, this boat is fully enclosed so that passengers stay dry. They certainly don’t need to don wet weather gear and PFDs.
That’s not to say the ride is any less exhilarating. Passengers still need a restraining harness. In fact Ocean Jet is the only company on the Gold Coast which heads offshore looking for rough water, hence the name emblazoned along the side of their hull ‘Ocean Jet’.
The Ocean Jet boat operating on the Gold Coast was custom built in South Australia in 2008 and powered by a pair of Yanmar 6LY3-380hp engines driving Doen 130 jet pumps. It was operated by the original owners at Tweed Heads until 2011 when it was purchased by Michael Gilmore and his son Kegan at Jet Boat Extreme.
“Two of our other thrill boats were powered by Yanmar 6LY2A engines,” said Michael Gilmore.
“We repowered Ocean Jet with the Yanmar 6LY2A to give us more power and standardise our fleet.”
“We have operated our jet boats with Yanmar marine diesel engines for ten years and have had a great experience with these engines and the Yanmar brand.”
Yanmar’s 6LY2A-STP engine is a turbocharged, direct injected, intercooled, in-line 6 cylinder displacing 5.813 litres to produce 440mhp (324 kW) at 3300rpm. With a dry engine weight of only 535kg (less gearbox) the 6LY2A-STP delivers industry leading power-to-weight Yanmar diesel performance.
The power output of 440mhp per engine delivers a massive amount of power to push this beefy, robust hull. This is a big boat which measures 9.0m LOA with a beam of 3.3m and tips the scales at 7500 kgs. With a full passenger payload of twelve, an extra tonne is added to the weight.
If that’s not impressive enough, one of the Yanmar 6LY2A-STP engines drives an air conditioning pump via a simple belt drive. The air con unit keeps the passengers on board cool in the enclosed cabin. On a hot summer day on the Gold Coast, that’s an essential and formidable task in itself.
Despite the size and weight of the hull, not to mention the steep deadrise, the Yanmar engines have the brute power to get the Ocean Jet along at 45 knots or almost 85 km/h.
On most trips the skipper runs at close to wide open throttle of 3300 rpm for virtually the entire journey. Even in spite of this heavy operating cycle, total fuel consumption for both engines is under 70 litres per hour.
“We run the Yanmar engines harder than most would but we’ve not had any problems,” Michael Gilmore said. “About the only concession to the hard work is that we change the oil at 100 hour intervals and not the specified 250 hours.”
Undertaking the re-power proved to be a little more involved than initially thought with the local authorised Yanmar Dealer. Marine Mechanical Services managed by Rob Arnold helped with the repower and undertook a range of important changes in the engine room. There was a new exhaust system, electrics replaced, fuel system upgraded and new engine mounts built.
“There is a lot to like about those Yanmar 6LY2A engines,” said Michael Gilmore. “A lot of other marine diesel engines that we looked at in this power category peaked out at 2700 rpm. Jet drives thrive on revs, so the higher revving Yanmar’s are perfect for our application.”
“The power to weight is also very impressive. In fact the brute power is remarkable, all 880 mhp of it under the hatch. With the engines immediately behind the passengers, it is amazing just how quiet they are.”
The Ocean Jet rig is pushed to its limit on every thrill ride. This is a business that operates 365 days a year with two or three thrill runs most days depending on the season. In the high season with the corporates also booking rides with the tourists, the Ocean Jet can run up to five times a day.
