When a boat builder of Aaron Beattie’s experience makes a suggestion on what kind of engine you would be better off running in your new boat, you’d be smart to take his advice.

Casting an eye over Aaron’s Lifestyle Yachts latest build – a magnificent 16 metre Roger Hill design power cat Omahu – Yanmar marine propulsion couldn’t be in much finer company. Omahu has been powered with twin Yanmar 6LY400 common rail diesel engines and in the builder’s own words; “you don’t need much throttle to get things going, that’s for sure!”

She is superbly fitted out with an American white ash solid wood interior and designed for long-range trips. In fact, the design brief was for a leisure vessel to range throughout the coastline of New Zealand’s South Island in the summer months and the Pacific Islands for the winter.

Along with a combination of generator and solar/lithium battery power systems, Omahu sports all the conveniences of modern live-aboard luxury including a water maker, washer and dryer, air conditioning throughout and even a dive compressor.

The 6LY400 not only wins in power-to-weight stakes, (tipping the scales at just 585kg), it is also cleaner and more fuel efficient than its predecessors thanks primarily to the way its fuel is delivered to each cylinder.

The 6LY400 has common-rail fuel injection in place of single mechanical direct injectors and is rated for leisure marine and light-duty commercial applications. There’s new pipe work to handle the higher pressures of the Denso common rail system, as well as a new 24-valve cylinder head, along with redesigned inlet and exhaust manifold to assist engine breathing.

This 3,300rpm-rated engine delivers pretty much all of its torque at just over 2,000rpm, yet at those revs is using around 22 litres per hour in fuel. At 2,400rpm, (a little over two-thirds of full rated rpm), the 6LY400 is outputting around 375 horsepower (at the prop shaft!) of its rated 400hp.

And with the 6LY400’s common rail technology using its fuel more efficiently than ever before, they deliver that horsepower with IMO Tier 2 and US EPA Tier 3 emissions certification.