New outboard for venture224

walt

.
Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
Electric is way nicer than gas except when it comes to energy capacity. Remember that energy is power multiplied by time. You can use a fixed amount of energy with higher power over a shorter time or make the same energy last longer by using lower power.

If you look at the links below, these both say that a gallon of gas has the energy of 36 KWH. (ie, 36 thousand watts * hours).
http://www.menloenergy.com/?p=535
http://www.science20.com/science_20/energy_density_why_gasoline_here_stay-91403

When comparing gas to electric, you really dont get anywhere near 36KHW. Some data from using Torqueedo and a 2.5 gas outboard on a Hobie TI shows that a gallon of gas is more like the equivalent of 5.2 KHW.

Using this number of about 5.2 KWH (which needs some more data but is probably ballpark), assume the two lead acid batteries just mentioned have a total capacity of 200 amp hour.. but if you want them to last very long, you use only about half that or 100 amp hour. At 12 volts, this means that two battery set has the capacity in Watt*hours of 12*100 = 1200 or 1.2 KWH. (you get the same watt hours regardless if the batteries are used at 12 volts or 24 volts).

Remember that one gallon of gas actually does produce the equivalent of 5.2 KHW. So the two big lead acid batteries have the energy capacity of .23 gallons - ie, just a little less than one quart of gas. Or put another way, it would take neary nine of those lead acid batteries for the same energy capacity as a gallon of gas. FYI, all this would look way worse for electric if we used that 36KWH in those links.

Electric is way better in all aspects but is seriously worse in the energy capacity aspect.
 
Last edited:
Sep 20, 2014
1,320
Rob Legg RL24 Chain O'Lakes
Electric is way better in all aspects but is seriously worse in the energy capacity aspect.
True, and a good explanation, but I've found in practice is that I have not ever had an issue of duration, even sailing multiple days without a charge. I have had only once where the total power was inadequate, which was in a storm where winds exceeded 50 mph.

It really depends on where you sail. I don't think I would choose it for Lake Michigan, but on inland lakes it works great.