Before I get started I'd like to make a request. When you respond to this post, please try to advance the topic, and the information that's relevant. Too often I see a lot of postings about how you shouldn't replace a diesel with an electric drive. Or I see people talking about safety and power ratios and other information that while useful and important is somewhat off topic. I know that there are some people who have concerns about the limits on power and the quantity of energy stored in diesel fuel vs electric batteries should preclude the choice of electric power. I don't. I understand your point of view, I think that it is valid, but I'm really interested in electric propulsion and want to know about what needs to be done to move forward on this project. I guess what I'm saying is that if you haven't actually replaced your IC engine with an electric system, think twice before you comment.
So here's the story. I have an opportunity to purchase a boat, 27ft. That has had it's engined pulled. The owner was thinking about doing a rebuild and the engine turned out to be not salvageable. The engine that was removed was a 10Hp diesel. I don't know the exact age of the boat (late 70's), nor its general condition. The manufacturer's listed weight is about 7000lbs. I'm considering a purchase followed by an installation of an electric drive system.
As I understand at this point there are really two directions that people are going on this kind of project.
1) Buy a commercial system that just drops in. The advantage of this idea, is that you're buying a known quality product from a company. They have done most of the heavy lifting of matching the parts and pieces and you're left with installation and purchase of a large quantity of Sulfuric acid and lead ( or other combination that yield electric energy). This process is relatively quick, the potential problems are well known ( sizing, installation) and once in place you're ready to go.
2) Design and install your own system. Potentially you might save some money here (this seems like a big maybe to me, because what you are trading it seems to me is your engineering time, (amateur) and your ability to purchase components ( limited buying power)) vs buying an pre-assembled system) to put together a system that is made of a few big pieces 1) The motor, 2) the controller 3) Mechanical Connection to the Prop Shaft 4) Throttle.
The home brew system seems like a great way to really learn and understand the components. It seems like you will come out learning a great deal about the design and building of electrical boat propulsion systems. I built my own computer to learn about that process, now I'm thinking about doing the same with electric power.
My questions are:
1) Did you buy an off the shelf product?
2) How much did you know about Electric Propulsion and the issues of design and safety before you bought?
3) How had you learned when your project was done?
4) How long did it take you to build your system from first idea, to motoring away from the dock?
5) A 10 hp diesel engine delivers about 7500 watts of energy. What size electric engine would be appropriate as a replacement?
6) If you were going to purchase an electric boat, would you be more or less likely to purchase based on home brew vs commercially purchased?
7) What are the biggest gottchas when designing and installing a home brew electric propulsion system?
8) How much time have you spent using your new electric yacht?
9) Have you ever found yourself out of power, or feeling you had too little power to get yourself out of a difficult situation?
10) Are you happy with the results? Would you do it again if you could start over again? If you answer yes, what would you change about the system you installed?
Tony
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