BtB Marine recently delivered a beautiful pair of identical line boats destined for the Western Australian ports of Fremantle and Port Headland. The port contractor asked specifically for Yanmar 6LY2A-UTP engines in both boats, an engine they know to be frugal on fuel, simple to maintain and incredibly reliable.

Each boat is running just a single 370hp (272kW) @ 3,300rpm Yanmar, yet performance and handling characteristics have proven spectacular for these 3.6tonne (lightship) work horses.

Like the purpose-built marine engine Yanmar powering it, the 800LB is a practical monohull design and described by BtB's Chris as a “fairly basic boat”. No-nonsense line handling and dive platform vessels they may be, but there has been more go into these aluminium work brutes than just a good engine.

“The client stipulated the Yanmar 6LY2A-UTP's because they know they’re a good motor and easy to service,” he explained. The 6LY2A’s have been coupled to Hamilton jet propulsion via a Twin Disc MG 5050SC transmission and a 400mm jack shaft in each boat, with BtB opting to use genuine Yanmar engine mounts also.

The Yanmar’s famous power-to-weight has again delivered beyond expectations. “The specification from the client was for a working speed of at least 21 to 22 knots,” Chris said. “The Yanmar and water jet combination has delivered a 30 knot top speed fully loaded, (33.5 knots lightship), and they easily do a cruising 21 knots at around 2,500rpm of engine speed.”

That’s impressive on-water motivation for the 800LB, given it has a 400litre fuel and extra 1 tonne carrying capacity fully loaded!

Power-to-weight is only the start of the 6LY2A’s credentials however, with this 6-in-line, 535kg (without gearbox) turbocharged diesel doing far more with its 5.8 litres of capacity than meets the eye.

A mechanically-controlled engine, this simple but powerful direct-injection, in-line marine diesel is much sought after by marine operators like ports, water police , dive charter and other commercial boat operators. Simple maintenance, long service intervals (250 hours) and easy access to service and engine vitals are a hallmark of this well proven Yanmar purpose built marine engine.