[Public-list] weight distribution and electric power

[Gordon Laco]

I did a bit of figuring on this issue back when considering an electric aux
in my old boat.  The water generator is not an inconsiderable drag while
sailing.  I fell back on looking at fitting a small Honda generator, which
would have done a fine job but there I was back with gasoline but this time
in addition to the extra batteries and lower thrust the e motor could
deliver...

Gord #426








> I have no idea how Dan is planning to recharge while sailing, but solar
> panels are not the only way to do this. 2 other examples are wind generation
> and water turbine generation.
> 
> Water turbine generation was used by Gelinas during his round the world
> cruise. It basically uses a propeller as a turbine, connected to a shaft
> which drives a generator. Since a motor and a generator are physically the
> same thing, most electric motors can be used as generators, and in fact,
> most electric launches are set up in exactly this way.
> 
> Regenerative braking in hybrid cars works exactly the same way. This
> technology is well established and frankly much older and more mature than
> photovoltaic solar power.
> 
> I don't know much about efficiency numbers, but if Dan figures he's motoring
> for 15 minutes to a half hour to get out of the harbor, followed by several
> hours of sailing, I am guessing that since the generator is running at least
> 10 times longer than the motor (assuming 2.5 hours of sailing for every 15
> minutes of motoring), he probably is not going to have a problem replacing
> whatever juice he took out.
> 
> Plus he'll have a sweet way to recharge his house batteries and replace the
> juice taken out by his lights and refrigeration and electronics and whatever
> else.
> 
> I wouldn't use the system while racing, though...that pesky 2nd law...no
> free lunches and all that.
> 
> JB
>


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