I don't want to be a devil's advocate, but have looked at going electric, as I currently have a boat that has a gas motor that is an unknown, as it has not run for a while, and there is water in the oil.
As a newbie, I now see that to go electric is not cost effective compared to a used diesel.
The range is in any case limited compared to the energy in a tank of fossil fuel, and so is the power available.
Judging from the postings and discussions here, many hours are spent checking consumption, battery condition, etc etc.
Having said that, however, there are extra things to consider where you might want to look at a wider picture.
There is no doubt at all that electric is convenient, easy to start!!!, quiet, and can provide all the power you need to maybe do most of your powered sailing, that is, primarily getting in and out of a dock or mooring. It is certainly the way to go. One massive advantage that I can see is that once you are set up with electric, you already have a large(ish) electric storage capability that can also be used for other things. This effectively lowers the battery costs for those items.
But, then we look at the charging options, especially assuming that you wish, or are forced, to be off the grid.
Solar panels might be good, but they have limited and ever fading life, and are hard to mount on a smaller boat, consume room on a larger one, and need fair amounts of strong daylight. They also add top hamper, and are ugly.
Wind generators are good, in fact, very good, but again, you need the wind, and they can be noisy.
The quick and certain way is to charge using the grid, or fossil fuels.
Now, most sailboats have fossil fuel engines that are way too big for the required hull speed. This means that you have residual power that is wasted, or maybe I am wrong in this thinking?
So, by ADDING electric to an existing ICE setup, instead of it REPLACING an ICE, you have far more versatility.
You even have heat that can be used, if climates require it. In fact, as an ICE consumes most of its fuel in creating heat, it would be crazy not to use that heat, if we look at a bigger picture.
You could even drive a compressor and store 'cold' if needed.
With the right setup, you could boil a kettle using exhaust heat. There would seem little point in having electric propulsion, and then use propane or oil to heat food, unless you are OK with being grid dependent, and your sole goal is low running costs.
I am thinking that electric as a sole source might only be really viable for a tropical climate, or for saving a whole bunch of money if you can charge from the grid.
Perhaps a mindset to have might be, at least for a sailboat cruising situation, that the ICE engine is primarily a heater, and can charge your batteries really well, and simultaneously provide propulsion, while producing that heat and charging. With that mindset, the electric idea becomes a whole lot cheaper. For a start, if you have a gas or diesel engine then you can afford to have a lower powered electric setup. On a boat that needs, say, 6hp to achieve hull speed, but has a 25hp gas engine, you could probably use 3hp as far as electric goes, and maybe go with an on/off switch rather than controller. Same as the initial setting up of the batteries, you could go with less storage capacity, as you have the fossil backup.
With a more designed setup, you could drop the ICE hp to maybe 15hp, and run the electric in addition, if more emergency power is needed.
I believe that there would be greater use of electric propulsion if it was significantly cheaper to originally set up. It would be interesting to see the development of a combo motor package, like an outboard with an electric drive built in as well.
I guess what I am suggesting is a designed (at least to some degree) from scratch hybrid. Maybe it has already been done.
Right now, I just got a good deal on a whole gas engine for spares. But, I still see electric as being attractive.
Any ideas how I can incorporate both, assuming the gas engine will work out OK as a smelly inboard and battery charging heater?
The obvious would be an electric outboard, but that is unattractive to me. Would it be practical to add another prop shaft? Maybe add a tubular shaft, or more accurately reduce the current shaft and have it running in a tube that has the same outside diameter as the current shaft, and has the electric drive going to it so that both props are on the 'same' shaft?
John
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