We lived on a hybrid boat for over three years and have converted to diesel. We have since sailed to Fiji from New Zealand and have built enough experience to share our perspective on the two systems.
Motoring
Nothing was cooler than motoring in or out of a public marina/dock silently on battery power. I still kind of miss that but that was a rare event. More importantly, with the hybrid system it was always nice to know it was on. Ie, if we needed a bit of power to avoid an obstacle, it was always instantly available. The diesel engines have to be started before use which adds a few seconds. This is a minor inconvenience really and simply not putting oneself into situations where a bit of extra power might be needed resolves this. However, it’s a comfort lost.
On the upside, the diesel engines are significantly more powerful than the old electric motors. We can motor into 20-30 knot winds with ease whereas before, this would be a struggle. Our boat, with vertical windows (great for interior space) has a lot of wind resistance when going into wind so we really feel the benefit of the more powerful motors.
Regeneration
Regeneration really only worked when on a long passage where we had good winds and could turn on the regeneration for 6 to 8 hours each day. I was surprised on our recent passage that I had to run the generator for an hour and a half to two hours per day to make up for the power consumed by the boats systems. The down side of regeneration is loss of boat speed. Even when the regen is switched off, the large props produced significant drag on the boat. With regen on we’d lose another knot. So our recent 8 day passage would likely have taken 9 days on the hybrid system.
Was the extra diesel consumption worth the extra day ashore? When we first set off I thought not. We had all the time in the world. An extra day at sea to save fuel seemed a no brainer. Now I have a different opinion. An extra day at sea is one less day on land. We can’t zero value our time aboard. This trip cost something to set up and it costs something each day we carry on. Also, an extra day at sea is an extra day we might run into bad weather. Speed is important.
Factor in the assumed reality that motoring on the hybrid system was less efficient than motoring on straight diesel, it’s hard to be sure that we ever saved any diesel at all on the hybrid system.
So, in hindsight, the regeneration aspect of the hybrid system probably was the biggest disappointment.
Sailing
As mentioned earlier, the boat is now faster. We have smaller props developing less drag. We go faster under sail. It’s hard to tell if motor sailing is any less or more efficient under either system. On the hybrid system we would give a light push under batteries for a few hours before starting the generator and recharging the batteries. Now we give a gentle push with one engine running under low revs. Hard to tell. The hybrid system was certainly quieter even with the generator running.
Resilience / Support
About once per year the hybrid system would experience a breakdown in one of the charging banks. Lagoon would always ship us a replacement but that could not last forever. The replacements were obviously coming from boats that had been converted. In fact, the original premise upon which we’d bought the boat had fallen through. We’d been interested in hybrids for some time but had always been put off by having something that may end being hard to find anyone who could support it. When Lagoon launched the 420 with the promise that all of them would be hybrids, things changed. Lagoon produces hundreds of each model so the prospect was that there would be hundreds of hybrids out there within a few years and all sorts of folks springing up to provide support services. That didn’t happen. About 70 hybrids were built of which there remain about 15 worldwide.
So the only support comes from Lagoon which, while being faultless so far, can’t be trusted to run forever. This lead us to the decision to convert to diesel. Now that we have we feel a lot more comfortable having propulsion systems that can be maintained almost anywhere in the world should an issue occur.
Other aspects
While down in New Zealand we really appreciated the availability of hot water when motoring on the port engine. With hot water also available when running the generator, it was relatively easy to ensure that we had hot water each day regardless of what we were doing. Here in the tropics it’s not so important but we certainly appreciated it there.
With Sam aboard, we are running the inverter a lot more than normal. However, it is noticeable that we have to run the generator more than we used to. Before we had two additional banks of chargers to charge the drive banks which we could tap for house energy while at anchor. We just don’t have that charging capacity anymore which translates into more hours on the generator. Certainly with less load on the generator and hence less fuel consumption per hour but the extra time is noticeable.
Summary
We enjoyed our time being a hybrid boat but definitely prefer the diesels. Mainly it’s a case of less worry. The hybrid system was over complex and had one connection anywhere broken it would have been a nightmare to troubleshoot. Now we have a simpler boat with components folks widely understand. We feel more secure.
Compared to other hybrid implementations I’ve seen the Lagoon hybrid system was over engineered. It was way more complicated than it needed to be. Some features, like the automatic starting and shutdown of the generator while motoring, we never used.
Future thoughts
I don’t think our experience would suggest the idea of an electric boat is dead. If anything, I believe we have learned enough to suggest a different future for electric boats. There are plenty of exciting developments which would make future electric boats more desirable.
Battery development. The auto industry is driving huge advances in battery development. Already, lithium ion batteries are becoming more economical for boats than standard batteries. In time this will only get better. When power can be stored for many hours of motoring we’ll be in a good spot.
Passive charging. A cruising boat spends a lot of time at anchor. There are developments in the solar charging world which could result in whole boat surfaces being solar power collectors. Coupled with greater energy storage, being able to passively top up propulsion batteries over a period of days would be ideal.
Motor power. The motors need to be as powerful as diesels.
Power Management. A better way needs to be found to share the power in the drive banks with the house systems. The 72V/12V cross chargers on our old hybrid system were inadequate. A generic system that can take power from solar, wind and generator and feed it to the drive and house banks would be ideal.
Regeneration. An option only for those who are prepared to sacrifice speed for power. Perhaps a tow generator feeding into a generic power management system.
All these things will need to come together to make a different kind of boat. Given how the marine industry lags everything else I don’t see anything really happening for 5-10 years.
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