One of the propositions we often hear with modern hybrid diesel-electric mid-range cruisers that are fitted with solar panels is that the boat will, or at least should, operate all electrical functions overnight without the need to run a generator.
This “silent mode” is a very attractive idea as none of us enjoys sharing an anchorage with a boat running at genset. But can this really work? And, what size battery bank do you need to achieve such energy independence?
It turns out in a real two-day test in Spain aboard a Greenline 45 Fly Hybrid, British yachting journalist Alex Smith put the concept to the test. He was provided the boat by the Spanish firm Argo Yachting and set out for a cruise to a nearby anchorage to see what happened to the electrical system in real-world conditions.
Unfortunately, the weather turned sour so Alex and the Argo Yachting crew headed back to the marina where they could run their overnight “silent mode” test in comfort and safety. They operated the vessel as though they had a family of four aboard who kept all the lights on, watched TV, charged their phones and computers, cooked, washed up and then stayed up a little late to enjoy vacation time.
The boat was equipped with a 44 kWh lithium-polymer battery bank that was 96% charged when they moored the 45 in its slip for the night. After the full evening of use, but without needing to run the AC, they got up next morning and showered to give the water pumps a run at the battery bank as a normal family would.
Following breakfast and the boiling of much water for tea, Alex switched on the MFD, which was linked to the sophisticated battery control and monitoring hardware to see how much damage had been done and whether or not the “silent mode” concept actually works.
The result was encouraging. Starting at 96% charged, the large battery bank had run down to 64%, or roughly two thirds of its full capacity. That meant, the theoretical family of four, could go on living aboard at anchor all day and through the next night on existing battery capacity.
While Greenline has been a leading developer of hybrid propulsion systems and “silent mode” operation, they still are faced with all of the exigencies of marine batteries and the high energy consumption of modern cruising boats. So, I would say it is gratifying to see a test like this test proved the concept so conclusively.
Hybrid propulsion works and reduces a boat’s carbon footprint. And, all night “silent mode” works as it both reduces that footprint farther and eliminates genset noise pollution. These are good things.
You can read Alex Smith’s full test and his comments of the Greenline 45 Flybridge Hybrid in Motorboating & Yachting.
