The problem is that nobody has done it yet. If you think about the hybrids that are available today, both cars and boats, they have small electic drives and much larger IC drives. They are still configured to be primarily IC vehicles. This allows the electric side to handle slow speed requirements and sometimes to assist the IC engine under temporary high load situations. Even Dragonfly, the "slow boat" electric hybrid that has been discussed here recently is running a 6hp electric motor and a 60hp diesel engine.
For your project, the first step would be to identify your power requirements. How big (in hp) are the engines in your boat today? Do you believe that you would be OK with engines that have half the hp? One third? How small would you go and still feel safe?
Once you've got that number, you can convert that demand to electric. The common conversion is 2-3hp IC to 1hp electric.
Since there are a whole bunch of different 42' Chris Craft models, I randomly checked a couple of Constellations. The lowest powered one was running 395 total hp. If you cut that in half because you feel the boat is overpowered, you're down to 100hp per engine. Using 2.5 to 1, each replacement motor should produce 40hp. Each motor should be rated to 30kW or 60,000W for both. Assuming a 144V system, both motors could draw more than 400A under normal conditions. If you're going without a decent sized battery bank to buffer the loads, you'll need a 60kW generator to drive with half the available power of the engines that are there today. You know more about your boat and can do the similar math for your boat.
And to run electric drives directly from a 60kW generator, you're going to need a custom control system that will adjust the generator output to drive demand. I think that virtually all of the diesel-electric systems use some sort of battery bank to meet small demand without having to fire up the on-board powerplant, but the controlling hardware/software would have to be built just for you. Without plenty of others doing this before you, there are some major components that aren't available "off the shelf" or out of the junkyard.
It's not that it can't be done, but it can't be done easily.
Fair winds,
Eric
--- In electricboats@yahoogroups.com, "\"D\"" <dracoeterni@...> wrote:
>
> This is what I am trying to figure out myself is it possible with the advances in technology to downsize this system since the advent of hybrid cars and now the new boats coming out as well
> one would think so but to tell anyone in the wooden boat capitol my plan it is looked at as sin and not doable. my question here is why? Outside of just "it can't" what are the formulas exactly that make it impossible?
No comments:
Post a Comment