Sleipner’s new Hybrid Power Centre offers all the power of a diesel generator without the weight, noise & fumes
The irony of running a large motor yacht is that even though it’s propelled by a pair of big diesel engines, you still need at least one more to generate electrical power for all its ancillary systems. Not only does this mean running three or even four diesel engines under way, but the constant noise and fumes of the generators at anchor can take the edge off that perfect unspoilt bay you’ve spent so long getting to.
Now, thanks to a new off-the-shelf solution from Norwegian marine technology company Sleipner, that problem could soon be a thing of the past.
Called the Sleipner HPC (Hybrid Power Centre) system, it comprises a pair of 48V DC ‘super-generators’ that run off the main engines’ PTOs (Power Take-Offs), a battery bank to store the power they generate, a Smart Power Controller to manage it and an intuitive User Interface to control it all.
While the idea behind this isn’t new, it’s the first time a single manufacturer has developed a complete integrated system that can take care of everything from the boat’s thrusters and stabilisers to its power generation and management systems. With the sole exception of the battery bank, which the customer can source and specify to suit their needs, it’s all made by Sleipner, promising a seamless user experience and an easier installation process.
The HPC system can draw power from both the batteries and PTO generators then divert it to where it is needed most
Generation game
The heart of the system are the two 48V PTO generators. These are designed to fit onto the standard power take-offs of all major marine diesel engines, with a torque band of 25-120Nm. Sharing much of their internal structure with Sleipner’s electric thruster motors, they use the excess torque developed by the engines to generate electricity.
Such is their efficiency that even with the engines ticking over at idle, each one can generate up to 5kW. At cruising speed that rises to 25kW or 50kW across both engines – enough to charge a powerful 100kWh lithium battery pack in just two hours.
Generating this much power does create a certain amount of unwanted heat so a built-in water cooling system keeps it operating at the correct temperature while an integrated inverter and controller ensures a steady supply of power that can either drive 48V equipment directly or recharge the batteries.
The new HPC ‘super generators’ slot onto the engines’ power take-offs and can send power directly to 48V systems, like stabiliser fins, or the battery
One of the first yards to offer it as a factory fit option is Turkish builder Numarine. Marketed by Numarine as the ‘Mk2 Super Silent Pack’, it enables its latest 88ft explorer yacht, the 27XP, to offer a full night at anchor in complete silence with the air-conditioning and stabilisers running but without the need to run a generator.
The benefits are just as worthwhile during the day, when guests can eat in the cockpit or swim around the boat without the sound and smell of a diesel generator spoiling their enjoyment.
All the systems in green are supplied by Sleipner but the battery pack can be sourced by the customer to match the boat’s requirements
Smart thinking
To make this possible, Numarine has fitted the boat with a high capacity 92.8kWh Lithium Iron Phosphate (LiFePo4) battery bank linked to Sleipner’s Hybrid Power Centre and a full suite of Sleipner dynamic aids, including 48V DC bow and stern thrusters as well as electrical curved fin stabilisers.
This maximises the efficiency gains as it allows the PTO generators to power them all directly and means the boat can be run without the extra weight and complexity of hydraulics. On the hard top, 5.6kWp of solar panels provide an additional boost to the batteries, extending the time it can spend at anchor in silent mode.
Most boats will still need a conventional generator to avoid the need for running the main engines at anchor if you do ever run low on power, but it should significantly reduce the running hours, fuel consumption and servicing schedules to the benefit of guests and crew. It may also enable the fitment of smaller, lighter generators and improve the weight distribution by relocating the batteries further forward.
The HPC Smart Controller is linked to a series of modular switches so it can temporarily shut off non-essential items when power is needed elsewhere
Another key function is the system’s ability to prioritise power where it’s needed most. For instance, if you’ve depleted the battery reserves overnight but still need to use the thrusters to manoeuvre out of a tight spot in the morning, it will temporarily shut off power to less essential equipment, such as the water heater or stabilisers. This is all managed automatically through the intelligent HPC Controller and a series of modular smart switches that can be added to at a later date, future proofing it against further modifications.
Verdict
The advent of new technologies such as joystick control, station keeping and zero-speed stabilisers means the demand for both power on board is only getting bigger and yet the pressure to reduce unwanted noise, emissions and fuel consumption is growing just as fast.
For boats in the 60-90ft size bracket, which might previously have opted for hydraulic thrusters and stabilisers and always-on diesel generators, the new Sleipner HPC system offers a genuine alternative.
By replacing the hydraulics with 48V electrics and the diesel gensets with PTO super-chargers and a battery bank, owners can enjoy all the benefits of a fully stabilised, easy to manoeuvre boat and plentiful power on tap without many of the usual drawbacks. Numarine may be the first yard to adopt the new HPC system but it certainly won’t be the last once Sleipner officially launches it this autumn.
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