For propulsion, a 110v generator is the wrong choice. You have to pair it with a high amp output 110v charger to create a system that can keep up with the load and you are just wasting juice as you go through all the voltage conversions.
Here are hard numbers from the two electric motors currently installed on my boat. You can read details of the project so far here.
http://rudderprop.com/
Both motors are MinKota RT55EM's. They are 12 volt, 55 lb thrust motors. I choose the 'Engine Mount' style because of my unique installation design. They are designed to be mounted on the cavitation plate of a large outboard. The motor controller is separate from the motor itself and can be mounted inside the boat. Instead, I removed the mounting hardware they came with and created my own that mounted them in my 26X rudders. Right now I have these4" pitch Kipawa props on them.
http://www.kipawapropellers.com/index.html . Once the system is complete they will have higher 8" pitch feathering props that just become extensions of the rudder surface when not running.
With both motors running at full power my very accurate Link 10 Amp hour meter recorded just under 60amps of load. One alone consumed 30 amps. This was a very consistent load as we made a one hour long cruise both down and up wind in a 10-15 knot breeze out on Lake Washington. They had no problem at all moving the boat into this breeze and there was not even a 1 knot speed difference into the wind verses with the wind.
At the moment I have two 6v Golf Cart batteries installed giving me a 225ah 12v battery bank. You should never discharge the bank further than 50% so I have 2 hours of run time on battery alone. My plan for the completed system is to add another pair of 6v batteries giving me a 450ah bank and 4 hours of cruising under battery power alone.
To extend this range I have paired a Christie Engineering G12-80 12 v generator with the system.
These are sold in the states by Alten,
http://www.altenbatterychargers.com/bat ... ineup.html .
The 80 amps of 12v power is more than enough to run both motors at full speed without needing any power from the battery bank. The efficiency of this system is quite amazing, read the info I posted about this at my rudderprop.com web site. The generator will of course charge the batteries as well if needed and also run a ton of 12v amenities while out on a cruise.
Take note that these 12v generators, and most high amperage 110v to 12v battery chargers have two voltage levels. You choose the lower one for 'online' use when either is providing power power for devices such as propulsion motors. You choose the higher one for battery charging.
If you do go electric and use trolling motors be sure you do not use any of the 5 speed motors on the market. These are very inefficient and actually use the same amount of power on low as they do on high. Rather than sending less power to the motor on low they use 'load coils' to absorb the excess power and turn it into heat. This is just a waste of power. You want to buy the better models that use what MinKota calls it's 'Digital Maximizer' giving you a infinitely variable speed that uses much less power. Other brands have the same technology that goes by different names. Just never use a cheap 5 speed model from any brand.
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