A look at the new M17 Scania hybrid diesel-electric system
Marell’s latest patrol boat uses a hybrid diesel-electric motor to chase down bad guys. Hugo Andreae was one of the first to experience it in action.
Did you think all hybrid powered boats were slow, boring craft with limited range and sea-keeping best suited to plodding along lakes and rivers? Then it’s time to think again because Swedish yard Marell Boats has teamed up with Scania motors to develop a diesel electric hybrid craft that is just as fast, fun and robust as most petrol powered super boats – and we were among the first to experience it.
Called the M17, it’s an all-aluminium deep-vee performance craft designed primarily for use as a patrol boat, although a leisure version is available. Power comes from a pair of Scania hybrid diesel electric engines linked to MJP waterjets. Together they are capable of powering the M17 to a top speed of more than 50 knots, yet it will also cruise all day at 8-10 knots in almost total silence using the electric- only mode. Not only does this make for a much quieter and nicer environment for the crew, it also gives better slow-speed control as there is no lower limit to the idle speed.
Hugo Andreae is one of the first to experience the M17 in action
When more speed is needed, the big 16-litre V8 diesels kick in automatically, delivering up to 1,150hp per side in addition to the 230kW (308hp) electric motors. The result is electrifying, in every sense of the word. While not the quietest or smoothest of engines we’ve tested, the big Scanias provide serious shove and a fast cruising range of over 500nm.
Electrifying acceleration
We jumped on board the M17 Hybrid for a demo run at the Seawork show in June, where it was being exhibited to potential commercial customers including police, customs and even special forces – silent mode being of particular interest to the latter. With Marell founder and CEO Patrik Söderholm at the helm, he was able to demonstrate its full range of abilities.
Everything is designed to be as simple and ergonomic as possible so the skipper can focus on driving
That started with some skilful manoeuvring out of the dock using electric power alone. Being waterjet-driven there was still a considerable amount of turbulence behind the boat but the usual noise and vibration of combustion engines was completely absent. Although the Scania electric motors are rated at 230kW each, they can deliver short bursts of up to 280kW (375hp). Fed by four 104kWh battery packs, they had no trouble shifting the 57ft M17 along Southampton water at speeds up to 10 knots, even when laden with at least ten guests and four crew. We didn’t have time to test the estimated 7-8 hour electric run time but given the low power consumption at displacement speeds, we’ve no reason to doubt it.
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Diesel range
Only when Patrik pushed the revs above 1250rpm did the two big diesels fire up. One of his key objectives when developing the hybrid system was to make it as simple and intuitive as possible. When chasing down a drug smuggler or evading enemy fire, the last thing you want to be doing is fiddling around between different drive modes so it all happens automatically.
The 16-litre Scania diesel engines deliver a thumping 1,150hp each
Whether it was the contrast with the silence in electric mode or the amplifying effect of the aluminium hull and wheelhouse, the big V8s did seem quite vocal when running at speed. Then again it’s not often we get to test engines of this size and power in something as small and focussed as this. The effect is dramatic, the combined torque of the big V8s and the twin electric motors hurtling the M17 across the water with the speed and agility of a true superboat. We eventually ran out of steam at 48 knots, rather than the claimed 50-55 knots, but given the number of passengers on board that’s hardly surprising.
Secure sea-keeping
What did surprise us is how quickly it accelerated out of the turns. With no shafts or sterndrive legs to grip the water, jet-drive boats are prone to spinning out when cornered too rapidly but by easing the throttle momentarily to allow the hull to sink lower in the water then using the instant torque of the electric motors (up to 2,000Nm per side from 0-1,300rpm) to power it out, Patrik pulled a full 180-degree turn while barely losing any speed – a very useful attribute when chasing down the bad guys!
Scania supplies the full diesel electric drivetrain while the waterjet drives are from MJP
It’s not all about speed and power, however. Another benefit of the hybrid set-up is that you can use one diesel engine to power both water jets. In this mode the electric motor on the active engine becomes a generator, sending power to the electric motor on the other driveshaft. By alternating which engine is running, you can halve the total number of hours you’d normally put on them, extending their working lives and reducing the servicing bills as well.
Verdict
While Marell hasn’t yet built a leisure version of the hybrid boat, there is no technical reason why it couldn’t – it has already built an M17 for a private customer with a full cruising interior and Volvo IPS650 drives – but the reality is that the cost is likely to prove prohibitive. And while we don’t have the figures to prove it, dragging around the extra weight of those big batteries is likely to offset any reduction in CO2 from the electric motors.
Twin screens show which mode is engaged but the computer automatically decides when to fire up the diesels
So while this remarkable boat may not yet make financial sense to a private buyer, it does offer some very clear benefits to the commercial sector and proves once and for all that hybrid boats can be just as fast, exciting and capable as petrol or diesel powered craft.
The electric motors bolt directly onto the gearboxes
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