Yamaha reveals hydrogen-powered XTO Offshore V8 outboard engine

The prototype “H2” engine, based on a 450hp Yamaha XTO Offshore outboard engine, looks surprisingly conventional apart from what looks like a new fuel rail and injector system, suggesting that it will burn hydrogen gas instead of petrol when it hits the water for the first round of trials of the technology later this year.

However, alongside the H2 engine, on display at this week's Miami International Boat Show, was a hull from offshore fibreglass specialist Regulator, featuring a bespoke fit-out of how the custom hydrogen fuel tanks, built by US-based engine tuning specialist Rousch Performance, will lie under the cockpit floor.

Hydrogen is very different to other fuels in that it needs to be stored at very cold temperatures – in its liquid form it needs to be kept below -253 degrees Celsius – and at very high pressure.

However, a hydrogen bowser can refuel a tank in a very similar process to filling a petrol tank, although with a few extra precautions added to the process.

One of the issues that car makers have noticed about hydrogen is that it doesn’t store in tanks very well – the H2 molecule is so small that it can pass through the skin of the tank made to hold it; if left, a hydrogen tank will tend to lose half its fuel through leakage in around a month.

The benefit of hydrogen is that it produces no emissions. The fuel enters the cylinder as a gas and is burnt with the oxygen pulled into the cylinder, with the reaction producing pure water.

Yamaha US marine business unit president Ben Speciale said Yamaha was exploring all possibilities to achieve carbon neutrality by 2050 

“That goal within the marine market can only be reached through an approach that leverages multiple solutions,” Speciale said. 

“We believe hydrogen is a viable method of achieving these goals. Yamaha wants to be a leader in this space, and we encourage others in the marine industry to become involved as we look for ways to build infrastructure and new policy around innovations.”

Regulator’s hydrogen-friendly hull is based on the Regulator 26XO centre console, a boat usually powered using a 300hp to 450hp outboard engine.

The prototype hull will also help Yamaha and Regulator shape the standards that will need to be built into hydrogen-powered boats to keep them safe – BMW had to build a special vent into the floor of its H2-fuelled Hydrogen7 luxury sedan to safely vent the fuel tank in the event the car ended up on its roof.

Speciale said Yamaha would use its relationship with Regulator Marine to test the prototype in a premium boating environment and attempt to lead the way using hydrogen as a fuel source in marine environments. 

“We’re excited to watch this project develop and look forward to taking the next steps,” he said.

Yamaha has started ramping up its move to alternative ways of powering boats, announcing earlier this year that it had bought electric motor specialist Torqueedo.

Yamaha is the first mainstream outboard engine maker to consider a hydrogen-fuelled powertrain using off-the-shelf internal combustion engine technology.