Captain Michael Howorth looks at the development of marine diesel outboards, their benefits and how they are competing with the traditional gasoline outboards

Ironically it is just as the car industry prepares to do a complete u-turn and declare diesel, once thought of as being a cleaner alternative, the bad guy that diesel is now beginning to become more fully embraced in the outboard engine world.

The question is; will diesel catch on and displace the gas guzzler or will it too be given the kiss of death by the tree hugging environmentalists? Diesel engines are said to be ‘lean-burn’, meaning they use less fuel and more air to get the same performance as a petrol engine does. According to the statistics, diesel engines offer between 30 and 35 per cent greater fuel economy than comparable gasoline engines. So, while diesel fuel contains slightly more carbon than petrol, overall CO₂ emissions of a diesel engine tend to be lower. The higher energy density also means that burning a litre of diesel emits more greenhouse gases than burning a litre of gasoline, about 15 percent more, to be specific.

One notable company Cox are pushing the boundaries of marine diesel engines with its sights firmly set on commercial and military markets, but they understand that the marine leisure business is also lucrative. The company means business and has built its team with ex-Formula One engineers and management.

The irony of this whole diesel versus gasoline saga is that, rather like the very first motor car, the first ever outboard motor was in fact powered by electricity. Designed by Gustave Trouvé, it weighed just 5 kilograms and was patented in May 1880. In the future will the all electric outboard engine kill them both off?

XTO Offshore

The muscular new shape and dynamic look of the XTO Offshore immediately communicates its incredible industry-first concepts and technologies waiting to be unleashed. The first direct injection 4-stroke, with integral electronic steering, linking seamlessly to Yamaha’s Helm Master®.


Suzuki V6 marine engines are the most compact in their class with offset driveshaft for better balance, less drag and more speed


The CXO 300 has been developed from the ground up with a specific purpose built marine engine. Cast from aluminium alloy to keep the weight down and featuring a narrow-angle 60° V8 to reduce its footprint, it’s not just the most powerful diesel outboard engine in production, it’s also the most sophisticated.


Developed by YANMAR with a remarkable torque output, peaking at 111 Nm at 2,500 rpm, the Dtorque’s performance surpasses even the leading 70 hp fuel injected, four-stroke gasoline outboards. The Dtorque also exceeds EU RDC Stage II emissions regulations.

300hp V8

The new FourStroke V8 and V6 outboards are the smallest and lightest in their class. As with all Mercuries, they are engineered to go the distance.


The OXE Diesel 200 is the most powerful unit in the OXE product line. The turbo and the gearbox of the OXE Diesel 200 has been further developed to torque and power and to withstand the higher temperatures developed the increased effect.


The flagship BF250, BF225, and BF200 models have been revamped inside and out, adding features, updates and improvements that make these acclaimed V6 outboards better than ever.