Christian, I have mad respect for you by the way.
The capability side that you generally do not have with a diesel alone:
- 5.5kw of AC available + the 5000va quattro, which can supplement from the battery and give you a short term ~10kw peak AC load handling ability. Nothing to sneeze at. You can eliminate propane/alcohol stoves. I'm not a greenie, I just don't like things that have an explosive failure mode.
- Air conditioner at anchor -- not a big deal for you in so cal or PNE, but in Arizona summers... brutal trying to sleep in 95 degree 50% humidity weather, even with fans. Yes you could do AC, kind of, with a diesel+alternator+inverter, but you can't set up auto-start with that to automatically maintain a battery state of charge profile like you can with a genset. And you have to size the inverter for the start loads... and the batteries..and the wires...with a 'hybrid' setup you already have all of this in place, and you have a genset.
- Normal house loads can be handled from the 48V propulsion bank via filtered (ie not noisy) and sealed regulator(s), and propulsion banks tend to be larger than standard house banks, so you can go longer between needing to charge them at anchor. 12V starting battery kept floating by same types of regulator.
- Not if, but when, you have problems with your diesel, with the prime mover being electric you still have options. Where you otherwise would have to call a tow because of a bunk exhaust elbow or water in the fuel (and no more filters,) you now have the ability to limp in. OR blast in, depending on the state of your batteries are when you discover the problem, but I assume prudence would dictate that you don't purposely run your bank below 50%. And solar is a significant source of energy.. on my little 26 at the lake I can maintain about 2.8kts on solar alone. Yeah -- it's in calm seas. But if there was weather I would let that solar charge that bank while I sailed toward safe harbor, then use the stored power to get to the mooring/drop the anchor/get into the marina with authority. It may be a little inconvenient but not as inconvenient as having no option but a tow.
- The normal plusses of electric.. instant on, full power available. Relatively little maintenance of the prime mover.
Now this said, it's not magic fairy dust and you do need to take a fairly methodical approach to designing your systems so that it all comes together reliably. You need to read maine sail's articles on proper marine electrical connections
You need to get the right tools. You need to look at the available ABYC standards and adhere to them.
There are more individual pieces that can fail in the "ideal long-range energy source-to-propulsion path," (
fueltank->engine->transmission->propshaft vs.
fueltank->engine->generator head->charger->battery->motor controller->motor->gear reduction->propshaft) but there
are more paths with the hybrid solution, and as along as the (traditionally very reliable) battery->motor controller->motor->gear reduction->prop shaft path is working, (And individual components are not unreasonably expensive, and spare controllers, belts, motor could be reasonably kept on a longer-term cruising boat,) energy
source can be genset, wind, solar, fuel cell, dragged generator, .. ? Anyways, I enjoy this stuff, and have a good understanding of electrical and emergency power management as an extra class licensed radio amateur. For me it's a great fit, but not necessarily for everyone, and I understand that.
Because of the benefits from a systems perspective, I think integrated hybrid approaches like this are going to become more and more common from manufacturers, because they provide a more solid electrical foundation to the never ending desire for the comforts of home -- microwaves washing machines and all sorts of silliness (For the record, the fiance wants a microwave..hmm, maybe not so silly if I want her to go voyaging with me). A 45-60lb prime mover and reduction gear/belt drive are a lot easier to install and align to a prop shaft than a 300 lb iC engine. Lot easier/cheaper to replace, too.
Supersailor is absolutely right by the way.. it generally takes a little more than double the power to go an additional knot. so 3 knots may take my little 26' 400 watts. But it takes 1000 to make 4 and 1800 gets me 4.7ish..
Sorry for the book by the way !
Sean
WK7R