Yanmar sterndrives for SeaQuest 3600

The first pair of Yanmar's new ZT350 diesel sterndrives to be fitted to an Australian built boat have been hailed as a perfect match for the luxury SeaQuest 3600 Bridge Sports.

Mated to Yanmar 6BY2-260 engines, the sterndrives have SeaQuest's John Young marvelling at the low fuel consumption, almost silent operation and compact footprint.

The Sea Quest 3600 is a big, beamy luxury cruiser but a transverse bunk under the sports bridge limits the amount of space in the engine room. Young says the modest installation envelope of the Yanmar 6BY2-260/ZT350 package really came to the fore.

The twin engines fitted neatly alongside each other but still gave plenty of room for servicing. Hydraulic rams lift the teak laid rear cockpit to give unsurpassed access to the engine room.

"Quite apart from the lean fuel consumption, low noise and lack of diesel smoke offered by the new common rail-equipped BY2 series of engines, we were won over by the new ZT350 hydraulic clutch design that made gear shifting smooth and quiet," explained Young.

The ZT350 sterndrive boasts a multi-plate hydraulic clutch that provides a smooth and positive gear change and the precision forged gears bring the durability of stern drives to a new level. The two counter-rotating propellers maximise acceleration.

Despite weighing 6500kg, the engine package throws the 42 foot SeaQuest quickly up onto the plane.

Young says that at full throttle the engines peaked at 4200rpm and a top speed of 34 knots. Optimum cruising speed was 17 knots with a fuel burn of just 19.3 litres per engine per hour. The speed testing was done with 850 litres of fuel and 330 litres of water aboard.