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Cox Marine Sets Diesel Outboard Speed Record


'Pegasus' with a Cox CX0300 diesel outboard
The 21-foot 'Pegasus' with a Cox CX0300 diesel outboard

Cox Marine has set a new speed record for a diesel outboard with a top speed of 67.95 mph using their CX0300 engine.


The record is subject to ratification by Union Internationale Motonautique UIM, the world's maritime governing body, to officially declare the engine the World’s Fastest Diesel Outboard.


The record breaking run was performed at the 51st annual Coniston Powerboat Records Week.


Skipper Adam Brown was at the helm for the 67.95mph run on Coniston Water with a CXO300 engine. The new record is 5 mph faster than Cox's 2022 record of 62.84 mph, also set by Brown.


The boat was a 21-foot Hallett Vector V-bottom 210 S closed-bow boat named Pegasus.


Similar to the 'kilo runs' at the popular Lake of the Ozarks Shootout in the United States, boats attempting speed records are sent down a 1 km closed track with a running start. Top speed is measured at the completion of the 1 km route.


The Cox CX0300 engine was also running on 100% sustainable fuel.


In a press release, the team said both Pegasus and their supporting vehicles were powered by biodiesel blends from Coryton’s Sustain Racing. The mixture is made from 100% second-generation biowaste mainly from wood products.


According to Cox Marine, the Sustain Racing fuel offers a 90% reduction in greenhouse gas emissions compared to traditional fossil fuels.


“It’s fantastic to have been able to return to the spiritual home of British water speed records and better our records with the support of Coryton,” said Cox Marine technical director James Eatwell.


“We’d like to thank both Coniston Record Week and the Lake District National Park for their help and assistance in making this happen. Our team at Cox Marine has done some fantastic work in demonstrating how much further we can push the performance of our outboard technology while still being able to prove that performance does not need to be at the expense of fuel efficiency or CO2 emissions."


“The amalgamation of the inherent fuel efficiency of the CXO300 engine with Coryton’s low-carbon Sustain fuel has allowed us to demonstrate a record-breaking low-carbon combination at Coniston.”


David Richardson, business development director at Coryton, added: “From the waters of Coniston to the deserts of the Dakar Rally, we continue to prove how well sustainable fuels can perform whilst providing vital carbon savings for our racing partners. We can only hope that the results we’re recording will go on to inspire others and help secure more investment and interest for this solution long into the future.”


The news marks another positive turn for the emerging British engine builder. In November, the Shoreham, UK company announced a new rigging system for diesel outboards -- a move that will offer greater options for boat manufacturers looking to add diesel power to their offering.


The CX0300 platform is likely to garner more attention going forward. With a 300 hp powerhead delivering 503 ft lb of torque at 2250-3000 RPM, the platform generates more torque than a 425 hp gas-powered outboard. It also generates up to 30% better fuel efficiency that a standard 300 hp gas-powered engine.


You can get a behind-the-scenes look at the engineering of the CX0300 engine in the video below:

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