The previous post on Electric Vehicle Concepts got me on a mental track that I've had bubbling around for a while... is it going to be electric/solar or inboard (diesel or gas) or outboard. Inboard is great for the right kind of craft, but I don't think that's where I'm going right now. Outboard... yeah, for some boats I think this is a good choice. A better choice than some give it, in my opinion. The new 4-strokes can be reasonably fuel efficient, they are getting quieter, are self contained and in some ways embody the "KISS" principle fairly well (check out my version of KISS, also). A couple of big downsides are lack of heat and power for external use. You don't heat your cabin or get significant amounts of electricity from an outboard, in general.

That leaves electric. Preferably solar/electric, with a small generator as a supplement (at least until/unless solar cell and battery bank technologies enable us to do away with that entirely).

Why electric? Here's a bunch of reasons that show a lot of my thought process right now:

• History - you didn't expect that, did you? Electric powered boats have been around a LONG time... like the turn of the 20th (not 21st) century. They fell out of favor as the ICE (internal combustion engine) caught on, but they were there. They worked.
• Ecology - ok, we may not all be the "greenest" people on the planet, but I think most boaters want to keep the water and the Earth as nice as we can. Solar seems a good way to go.
• Costs - It may not pay for a while, but you don't buy much gas when you are relying on the sun.
• Simplicity - You lose a lot when you go solar, electric... and I don't mean power and speed.
  You lose things like:
  • Noise
  • Vibration
  • Oil changes
  • Transmission - you don't need one
  • Engine cooling system with the throughhulls, sea strainers, clogged inputs, etc.
  • Hot exhaust - sometimes a wet exhaust - this includes the smell and carbon monoxide dangers
  • Heat in general - yes, there is certainly some, but less than an internal combustion engine
  • Fuel tanks - with associated cleaning and leaking issues
  • Fuel filters
  • Weight - its held that even with the battery bank, by the time you get rid of the rest of this, weight is the same if not lower
• Low speed torque - electric has most everything beat here
• A BIG house bank :-)
  • Power for air conditioning and other house loads

Cabin heating will have to be carefully examined. I don't want to carry yet another fuel to keep the cabin warm (diesel heaters, etc.). A wood pellet stove might be interesting. Hot water fits in here, also. I guess propane might do these, but again, that's another system.
Now several items in that list are mitigated if you need a generator, but my opinion is that a small, self contained generator that is running at optimum speed to produce electricity isn't going to be a bad tradeoff. You can run the generator, charge things up, use it for house power, and shut it down when not needed. You are going to want (at least I am) electrically powered devices onboard anyhow. This implies an electrical system with charger, generator (probably), etc. Why not get double use?

Yes, you may get away with the alternator on the main powerplant, and if this works out on your craft, great. But it often doesn't fit the bill.

If you go with a small gas generator (the small Honda's are very popular), you can share the gas storage with what you are going to carry for your dingy anyhow. Do make SURE to handle the exhaust... too many people on land and sea poison themselves with these generators. This is no different than the danger you have with any other gas powered device... we can deal with that.

There are a few boat design issues that seem to be a requirement with today's technology to support solar power... if these fit, then...

• Displacement speed - you probably aren't running at planing speeds for long with electric
• Lots of horizontal space for solar cells - this is going to continue to improve as efficiency of cells improves, but if you can't walk on the roof, keep that in mind
• Low power requirements - some hulls can just cruise along with a more reasonable amount of horsepower than others. You probably don't want to shove a deep draft, heavy tugboat hull around electrically... at least until Mr. Fusion comes along.

Given costs and solving a few of the above problems... I'm thinking solar/electric.