Watch the record-breaking run

Breaking the record

A world first* for marine diesel outboard propulsion

Participating in this year’s 50th Anniversary Speed Week, held at Coniston Water in Cumbria, Cox Marine claimed a World Record title, for the fastest Diesel outboard* on Thursday 3rd November achieving an average speed of 62.27mph.

Returning to shore, experienced powerboat racer Adam Brown, said: “While there will, of course, be faster boats out on the lake today, it’s a great honour to be able to set a new record. There may be future diesel outboard powered record attempts, but Cox Marine will always be the first. This is a great time for a 300hp engine which is straight off the production line and not having been optimised for powerboat racing.”

With initial runs being carried out on regular diesel, before switching over to HVO100 fuel Cox Marine’s internal testing, carried out lakeside during the runs, have shown a 28% fuel saving over an equivalent 300hp gasoline engine and net CO2 emissions reductions of 92%.

*Record awaiting full official ratification by Union Internationale Motornautique (UIM)

The Pegasus speedboat

Looking out for a hero

Titling the boat Pegasus, after the winged Greek stallion, we sourced a 1990 21ft Hallett Vector. With it’s proven shallow vee hull design, we set about modifying it from its previous inboard configuration, to accept our CXO300, a 4.4 litre 300hp diesel outboard.

Keen to demonstrate the power and performance of the engine, we agreed to leave it stock and minimise alterations to the vessel. The team started by fabricating a custom lift plate for the transom, to reduce the impact of the hull’s very low freeboard, before replacing the conventional throttle with a custom-built foot throttle, needed to meet the events regulations.

With the engineering elements all but complete, the team turned its focus to Pegasus’ presentation. Picking up our metaphorical paint brushes, or in the case of Greg Fairlie, a literal one, we transported our 90’s maroon boat, to the sleek, lake skimming record challenger you see today.

Follow all the record-breaking activity across our social channels

Powering Pegasus – The CXO300

Great British Engineering

With development starting in 2010 and now being manufactured from our state-of-the-art production facilities in Shoreham by Sea, the CXO300 was launched to the marine industry in 2018, and currently remains the only, large capacity, diesel outboard engine, that’s been purposefully built for the marine industry.

Having overcome some large engineering challenges to get the CXO300 to where it is today, Project Pegasus serves as a great reminder of our accomplishments and we hope to further them, with the addition of a British Speed Record. 

Delivering 479lb.ft torque at 2250-3800rpm and delivering up to 30% better fuel efficiency when compared with other 300hp gasoline outboard equivalents, the CXO300 can also provide a service life that is up to three times longer than that of an average outboard.

Reducing Emissions

While the record attempt is indeed speed based, we also wanted to use it as an opportunity to highlight our broader commitment to the environment. Cox Marine’s innovative technologies are designed to help reduce the overall impact on marine ecosystems. After all, that was the whole reason for bringing the engine into the world in the first place. 

For this reason, the Pegasus team will be calculating fuel burn and greenhouse gas production for all our competitive runs, in the hope we can prove high performance needn’t come at the expense of our environment, and that the two can coexist. 


Less fuel*


Longer life*


Less maintenance*


More torque*

479 LB.FT
*Compared to an equivalent gasoline-powered outboard engine.

Alternative Fuels

Pegasus will initially run-on marine diesel, before switching to HVO100 fuel, synthesised from 100% renewable raw materials, such as; vegetable oils, animal oils and fats. This will further reduce the CXO300 net CO2 greenhouse gas emissions, by up to as much as 90%.

This will mark our first official run of a CXO300 engine on HVO (Hydrotreated Vegetable Oil) fuel, following its successful certification for the CXO300 earlier this month. 

It is our strong hope that the record achievement will encourage other marine operators and recreational users worldwide, to make the switch, in the interests of marine preservation and the wider environment.

Coniston Water

In the UK’s County of Cumbria, Coniston Water is steeped in the history of powerboat record attempts, British invention and bravery, thanks in no small part to Donald Campbell’s vessel Bluebird and his World Water Speed Record attempts there.

To say Coniston Records Week is ‘illustrious’ would be something of an understatement. The event started life on nearby Lake Windermere back in 1970 and marks the end of the UK powerboat racing calendar, attracting competitors from all over the world.

An officially sanctioned Union Internationale Motonautique (UIM) event, the 50th Powerboat Records Week will take place on Coniston Water, Cumbria, UK from Monday 31st October to Friday 5th November 2022.

From record-breaker to flexible
and economical outboard marine power

  • Designed for both commercial and recreational use, the CXO300 is a new generation of diesel marine technology, offering a high-powered diesel outboard for the marine market.

    This is an innovative alternative to gasoline outboards and helps meet the increasing demand for outboard brought about by reasons of safety and convenience whilst exploiting the higher availability of diesel refuelling stations around coasts worldwide.

  • Power, reliability and comfort are paramount when transferring owners and their guests to and from their yachts.

    The commercially-rated CXO300 delivers impressive performance, including 479 lb.ft torque (650Nm) from 2250-3000 RPM, allowing your tender vessel to move through the water in a controlled and smooth manner whilst sharing the same diesel fuel as the mother-ship.

  • The CXO300 has been uniquely designed, but that doesn’t limit its applications. After all, it meets all existing industry standards, so can bring its exceptional performance to a wide range of commercial
    and recreational vessels, including RIBs.

    The universal transom bolting pattern allows easy installation to a wide range of vessels, making re-powering easier than ever.

  • When delays in response times can have major consequences, the CXO300 high-performance diesel outboard engine quickly reaches its top speed of 4000RPM, getting you to where you need to be, swiftly and efficiently.

    The CXO300’s V8 4.4l twin-turbo engine generates significantly more torque at lower RPM and maintains this power across a wide range of engine speeds.