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What’s better than a Yanmar-powered line boat? How about two?

BtB Marine has 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 370mhp (272kW)@3,300rpm Yanmar, yet performance and handling characteristics have proven spectacular for these 3.6tonne (lightship) work horses.

Chris Hough who runs BtB Marine with his wife Eva knows how to build a tough boat that performs well. His successful 750ULR work boats with single OXE Diesel Outboard on the back, (an engine platform also supplied exclusively through Power Equipment), took the commercial boat building world by storm last year – but Chris and Eva have no intention of resting on those laurels.

Calling the latest BtB line boats build an “800LB”, this Naval Architects Australia (John Pattie) design almost looks too good to call a work boat on its rollout from the BtB factory, but its finish inside and out is still both simple and practical.

Like the purpose-built marine engine Yanmar powering it, the 800LB is a practical monohull design and described by 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.

“There are four water-tight bulkheads with a fixed hard pipe bilge system that we designed and built,” Chris explained.

“We also designed and built the exhaust systems on these boats – basically a five-inch pipe off the engine expanding to a six-inch wet exhaust (including a 100litre drum/box) and exiting on the port side of the vessel,” Chris said.

“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 knots lightship), and they easily do a cruising 21knots at around 2,500rpm of engine speed.”

That’s impressive on-water motivation for the 800LB, given it has a 400 litre 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.

Still a mechanically-controlled engine, this simple but powerful direct-injection, in-line marine diesel is much sought after by 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.

“In the 800LB, you can stand on engine bed and easily access all the service points on the Yanmars,” Chris explained. “There’s also at least half a metre between the forward bulkhead and the front of the engine, so you have easy access to belts and water pump on the front of these Yanmars too.”

Double-walled 45mm soundproofing in the engine room helps deliver a nicer boat to drive – and driving these 800LB’s is where Chris gets very enthusiastic! With a three-stick manual control system, (throttle, gear and bucket controls), the 6LY2A-UTP’s responsiveness do their job with snappy precision coupled to the Hamiliton jets.

“Without a doubt, maneuverability of these is about the best of any I’ve built,” Chris says.

With plenty of commercial skippering experience behind him, you can bet that’s no idle claim from Chris Hough.

“Once you get used to it, they are super-responsive – they are as good, if not better, than any other setup you can power this kind of boat with in my opinion.”

As a light duty commercial engine with low fuel consumption, (they could be expected to use 40 litres or less per hour at 21 knots on current estimates), the 6LY2A family of engines has been the platform or the incredibly successful and class-leading Yanmar 6LY-440 electronically-controlled common rail engine.

Find out more about BtB Marine’s vessels and boating services at www.btbmarine.com