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post #58 of Old 10-15-2012
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Re: Optimal propulsion system

Originally Posted by Stumble View Post

Tesla is using lithium ion batteries last I looked. Figure an energy density on them of about 2% by weight compared to gas. So to replace a gallon of gas you would need roughly 325lbs of batteries. The Tesla battery pack weighs around 900lbs, so figure the energy equivalent of 3 gallons of diesel. And they aren't cheap, the battery pack which is good for a nominal 4 years cost roughly $36,000. So even assuming electricity is free it's going to cost you $8,500 a year in battery packs.

At today's fuel prices you would have to be doing a lot of motoring to come anywhere close to justifying it from a cost advantage.
To you good sir, I concede that you win this argument, and you will win for a LONG time to come. This isn't about just energy density and cost though. The cheapest way to get from point A to B on the water is by ferry. Next best, is powerboat. We can't possibly justify all the design and space losses of our sailboat hulls, the weight of our keels, and the massive expense of our rigs and sails compared with a simple small engine that can push us at displacement speed.

In fact, most of us already have that engine aboard but prefer to use our cost-ineffective method of propulsion (sails) even though they usually make us go slower, we can't pick our direction and they require constant attention. Curious isn't it? We crazy sailor types must like things in our propulsion systems besides cost and efficiency then. See my post a page back or so on motor-sailing and why we like electric.


I have a sauna on my boat, therefore I win.
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