Andy, the motors and controllers most often discussed on this board are BLDC/PMAC motors between 5kw and 12kw. 12kw is roughly equivelant to a 15hp ICE. That is a bit marginal in boats your size, but of course it depends on your needs. But I would consider a salvaged motor and battery pack from a wrecked electric car. Maybe the controller from the same car, too. That will be higher voltage. Most electric boats under 35' or so use 48v banks. Electric cars typically go about 4x that voltage or higher. Those will be AC inductance motors, usually. A salvaged system would probably fit the "budget" definition. A brand new 20kw+ AC motor and controller will, with a large bank of LiFeP04 batteries, definitely not be a low budget system. If your power needs are truly modest, you could get a decent 10kw to 12kw motor and controller for about $1500, and a 96v bank of golf cart batteries would run a minimum, with tax and core charge, of about $1600. A reduction gear would be somewhere in the neighborhood of $500. Steel for a good motor mount to hold your reduction gear, motor, and (recommended) a thrust bearing. You would need a couple hundred bucks worth of cable, lugs, wire, etc and a throttle which could be a $1 potentiometer or a fancy unit for $100 or so. You need an instrument panel. Basics, a cheap chinese panel meter that gives volts, amps, watts, and watthours used, then a tachometer and also a GPS speedometer, maybe also a charging current ammeter if you will be charging underway with a portable generator. You will need a shore power charger. A smart charger that can perform a proper equalization of flooded lead acid batteries. If not then a Variac and a rectifier for manual charging for when you want to equalize, and the smart charger for everyday use. You will want to take full advantage of that big bank and install an inverter and also a DC/DC converter so you have an alternate power source for 12v loads, or to outright replace your 12v house bank altogether. About $6k on a budget system that should prove adequate for the casual operator in undemanding environments. Oh you might also need a prop change. Depends. And the obvious companion to an electric propulsion system is a solar panel array and a decent charge controller. More $ but you will soon come to see that it is worth it to have at least 500w or so of solar panels.
One other budget option would be salvaging a large electric forklift. The main traction motor would of course be your propulsion motor. Other miscelanneaous motors from the same forklift might work out as windlass motors, a bow thruster, a winch for hauling a man aloft, etcetteruh. I think those are usually brushed motors so you must not have any propane or gasoline equipment onboard for obvious reasons, if you use a brushed motor.
Electric repowering can be pretty cheap compared to a new diesel but only if you really don't need a lot of power or range. Even with a big budget, range and power can be a sore spot with some folks because all things equal you simply can't expect a couple thousand pounds of batteries to give you the range of a diesel and a decent sized tank of fuel, especially as you approach hull speed. Smart electric boaters generally run their systems at half hull speed or less, BTW.
With your size boat, if you are having terrifying nightmares about coming up with at least $4k for repowering, you want a cast off diesel, or a mechanically sound, used 20HP outboard, or else some 14' oars, a strong back, and a cheerful outlook.
With a boat in the 18' to 25' range you can indeed get in the game pretty cheap. Again, depends on your performance expectations and resourcefulness. A big 36v used trolling motor and an ebike battery will get a teeny weeny boat in and out of harbor nicely for under a grand, and the system is portable. I made a shaft and prop that I can chuck into a cordless drill and pushed my pirogue along with it at about 3kt, a respectable paddling speed. A 34' steel yawl needs bigger medicine, unfortunately.
---In electricboats@yahoogroups.com, <andydee69@...> wrote :
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