Yanmar Powers Deep Sea Divers Den Into The Future

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The dive boat business in Cairns is a volume, quick turnaround operation which relies upon a high throughput of customers every day. With safety paramount, tight schedules and an eye to costs, the decision to power the latest launching, Reef Quest III with Yanmar 6AY-WGT engines, is well founded.

Reef Quest is an award winning, high speed luxury dive boat operated by Deep Sea Divers Den. Designed by Paul Birgan of Sea Speed Design in Brisbane, this all alloy vessel was built in Thailand. The fit out is exceptionally high, with much of the interior componentry being manufactured in Australia. Cabinets, tables and the galley for instance are made from Australian silky oak timber.

This vessel is designed and built solely for divers to undertake a day trip to the reef. Typically, Reef Quest carries a full complement of 80 divers and snorkelers. Overall the hull measures 26.0m and has a beam of 9.0m. Displacement all up is 60 tonnes.

A notable feature of Reef Quest is the full beam hydraulic dive platform. This lowers down, along the transom of the vessel, allowing divers the easiest access possible to enter the water.

Yanmar 6AY-WGT engines were specifically matched to the Reef Quest design, taking into account the weight of the catamaran hull, performance requirements and fuel consumption. The engines are coupled to Yanmar YXH240 transmissions with a 1.95:1 gear ratio.

The Yanmar engines installed in Reef Quest, are identical to those being used to power the Sydney Harbour Supercat ferries. While the hull designs and performance criteria have some technical similarities, the common thread is the demand for 100% reliability and dependability, day after day.

The Yanmar 6AY-WGT is a six in-line cylinder engine with a displacement of 20.39 litres and a rated power output of 911 mhp (670kw) at 1,938 rpm. The versatile 6AY Series is extensively used in many applications including heavy displacement work boats but also in many high-speed applications such as patrol craft and cray fishing boats. In Australia, the 6AY Series of engines has been exceptionally popular with ferry operators, for both in new builds and re-power applications.

A typical day for Reef Quest and skipper Glen Bailey commences with passenger loading for an 8:30 am departure from Cairns Marina. After clearing Cairns and the defined channel, the run out to the Great Barrier Reef is around 35Nm across protected water.

Through the day Reef Quest mostly rides at anchor, although the vessel does relocate to alternative dive sites which are close by, during the day. The day concludes at 4:30 pm berthing at Cairns Marina where divers disembark and the crew clean and reprovision Reef Quest for departure the following morning.

Every day the Yanmar 6AY-WGT engines log between 4 to 5 hours of operating time. On the run out and back, the optimum cruise speed is 22 knots at 1800 rpm. Fuel consumption is just under 100 litres per engine per hour. At wide open throttle, the Yanmar engines power Reef Quest along at 26 knots lightship, at 1850 rpm.

“This is our first experience with Yanmar,” said Glen Bailey, skipper of Reef Quest.

“The Yanmar 6AY-WGT engines are a great engine. They are also a reliable engine. They’ve given us no trouble at all. Their fuel efficiency is quite good and noise wise you can hardly hear them.”

With over 2,000 hours logged with the Yanmar 6AY-WGT engines on board Reef Quest, the owners could not be happier. The mechanical fuel management system provides a comfort factor which is highly valued by the skipper and his crew.

Based on the success and very positive experience of the Yanmar marine diesel engines, the same Yanmar engines have been specified in the next boat currently being built for Deep Sea Divers Den. Being powered by Yanmar 6AY-WGT is an unequivocal vote of confidence in both the Yanmar brand and the 6AY-WGT model.