Re: Can Electric Marine Propulsion Be A Reality (in pleasure craft)?
I think you are missing my point, and I hope you share this with your sons. Innovation ultimately requires a "why"? I am not suggesting that alternative technologies shouldn't be pursued for any application whether it be a spoon or a Space Shuttle. In both cases though you have to ask "why"? The answer is simple for the spoon, "hmmm, I guess there's no reason, "straw"? Oh yeah there is that alternative for some of the spoon's applications. Opportunity for additional designs? Maybe, but none come to mind, and no one is screaming for it anyways, lazy, poor or otherwise . . . Where's the market pull?
So then to boats, in this case pleasure craft. If your goal is fuel savings, but let's say you need 200 bhp to power a 20 footer for watersports and reasonably similar cruising to what we have today. That's the target market and application, and that's where this falls apart. That 200 bhp is available today and as is it is more efficient than using an electric drive with an Internal Combustion Engine (ICE) driven generator. Basically in that example the electric motor is a transmission, problem is that it is less efficient than the existing mechanical transmission so that arrangement doesn't work. OK, how about a Plug-in Hybrid Electric Vehicle (PHEV)? This is the same ICE driven generator with the electric motor, but add Batteries so that you get some of your "fuel storage" from electricity that is generated by wind or water, or coal or gas or nuclear. Cool, and it is cheaper, so maybe we can make an economic and environmental case. I could sell both to the public. Awesome. So let's hit the drawing board:
Batteries - costly and heavy but available
Engine - still need to be able to produce 200 bhp at the prop, so we need around 250 at the engine, no horsepower savings from the batteries as we need range that they can't provide on their own. (my requirement for safety and practicality) same cost, same weight.
Generator - added cost and weight but available
Add electric motor - available and probably similar cost and weight as removed transmission so that one is a push
OK, so we can do this, but we have to add weight and cost, and as long as we are running on the batteries we could theoretically save some money. I will assert though that there is no chance of an economic payback because of the added cost items and the relatively low fuel use in a pleasure application.
So now we have determined we can do it. It has some negative cost implications, but there are some unique attributes, so let's define the market size. and what percentage we will get of it. I don't have the number, but let's say there are 100,000 ( I am guessing this is high) new pleasure boats sold per year. 90,000 are under 22 ft. 80,000 of those are sold to those who are cost conscious, so there are 10,000 left. Of those 9,000 are sold to those who want go fasts, this isn't one of those so that leaves 1000 units available to us. Now out of those 1,000 how many want a boat that is slower (added weight), more expensive by say $50,000, and is basically clean for an hour then it is a less efficient facsimile of what is available for a lot. I submit it is Bill Gates and seven of his friends. Total market 8 units per year.
Do a similar exercise for an all electric version and you probably sell 2.
And although I may be an old fart, this is how the vehicle business is done, and alternatives is what my company does. BTW on-highway is a market size of many times more and why all innovation is pretty much done there . . .
