Lots of Q and some are not conductive to cheap D/E solutions.
1. Actual motor HP is easy.
Industrial and automotive electric vehicle technologies are plentiful, cheap and getting more common.
The electric motors are small, lightweight and reliable.
Essentially, they are usually brushless motors, with a controller that goes to high amps and high voltages.
Google MARS
You will not save a lot of weight, although electric engines are very lightweight, so are the smallish ICE engines used on cats.
Batteries will cost you a lot more weight than the engines will save.
2. Battery power
Expect to use li-ion or AGM batteries.
Li-ion are much better, and a lot more expensive.
You need to define your energy budget in kWh.
Battery costs for this use will be 20-100.000$, depending on whether you want short or medium range.
Assumes 70% hull speed, around 10 kW/h draw, and 2 hours cruise, ie 20 kWh battery capacity.
70% for 45 feet should get you about 7 knots for a cat at 10 kW/h ... or 14 miles for 20 kWh.
(In the ballpark, I think. Just an estimate.) +Add electrical needs for enetertainment.
Using the genny, your range is limited by diesel tanks, of cuorse.
3. Generator
An industrial generator will be cheap, reliable, and capable of any power desired.
Burden Surplus in the US center will sell you most of this stuff very cheap, and of industrial quality.
If you use a high voltage motor (likely, you probably want to do this), you should really use double insulated cable from the motors to the controller.
Ie the high voltage, high amperage stuff.
Expensive, but safe, and can be insured. Insurance, hence inspection, hence rated components, will be mandatory if you sell charters, as you stated.
Diesel electric will never save money in the initial installation (today).
Today, the range on batteries alone is very limited, unless you go quite slow.
Within 5-7 years, this issue is likely to go away, as will the huge financial penalty of lion batteries.
Expect about triple the range, and 20% less cost and mass, for a given investment in battery today.
There are a lot of variables you need to decide on.
You will need strong thrust bearings and mounts, for example. For a given Hp, the correct marine load factor is 5x the same Hp in light trucks.
Buying an existing kit will solve all this, at a (heavy) financial penalty.
Today, apart from EV conversion, the electric marine stuff is generally somewhat overpriced, imo.
This is likely to disappear, as installations become more common, tech becomes cheaper (controllers, batteries, electronics) and the penalty of very few experienced people in a niche market goes away.
This is a niche industry, and you you may know anything "marine" is 5x the price.
Most industrial stuff is usable as-is, but you will need it signed off by a marine architect/electrician/inspector, all at a cost, to do charters.
You do not need to buy "marine" rated stuff, but industrial underwater/heavy duty/adverse conditions/immersion service rated stuff.
The Q is very open-ended, as something like this may have a budget from 50 k$ (someones hobby) to 500 k$ (medium range, can afford 100k in battery and std "marine" rated stuff).
You needs and budget are going to be the deciding factor.
Hi Everyone,
I was wondering if I could get some basic help and pointers on setting up a diesel/electric boat.
I have a 45' catamaran (I'm building right now) with 18,000lbs max displacement. It's a non-planing sailing catamaran capable of 20 knots under sail in a very stiff breeze.
I do charters, so I have large house loads to contend with. This means that a diesel/electric system might save me weight and money over having twin engines, plus generator, plus solar, plus LPG system for cooking, plus heating system etc... etc...
I need some help though, because the electric stuff is new to me.
The basic requirements are as follows:
*30HP (20kw?) thrust for each hull
*Pod type electric motors (one for each hull) running from a main battery bank, no need for pods to rotate - I have rudders
*60HP?? 45KW?? DC Generator to charge battery bank and provide for house loads.
*Some appropriate type of battery to store power - a lot of power. Lots of cycles and quick charging. Ideas?
*Throttle/controller for drives, similar to Morse controls.
*Large inverter to support electric oven and/or electric heat and air conditioning house loads.
*Automatic control system to kick on the generator when the batteries get low and/or when the main drive motors are engaged.
Any ideas on where to start with the design of this propulsion system? Basic technologies to look at? Where to source the equipment? Specific things to look out for? Where to read for more information and to get my understanding of this type of system to a higher level?
Thanks in advance for any input.
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