Answers

Since we purchased this catamaran, everyone keeps asking me when I am going to convert to electric.  The answer is never.  The reasons:

1.  Drag.  If we went with pure electric, we would need three bladed props to regen power to the engine battery bank.  As proven, the drag from 2 - two bladed props, drops our sailing speeds by 2.5 knots. Can't imagine what 2 - three bladed props would do.

2.  Weight.  We also talked about how just 400 lbs of water, makes us lose 0.5 knots of sailing speed.  The only way to run with electric engines is to make a hybrid.  Until the past few years, all of the electric cats have been hybrid.  This makes a perfect motoring cat.  You can still go with folding props and just use your generators to charge the batteries.  But, saving a few hundred pounds in engine weight is quickly offset by the weight of the batteries.  With the Valence batteries, coming down in price, this may be a viable option now.  But, as we found, you do not have high current DC generators.  Unless you can get 100 amps plus, you cannot motor at hull speed indefinitely.  This means AC generators and large chargers, or AC motors.  Technology is still lacking.

3.  Many of the new cats, and mono's, come equipped with the electric engine inline with the diesel propulsion.  This may seem like the perfect option.  Maneuvering quietly, and with so much power, silently in the harbor.  Then turn on on your engine for normal motoring.  So, now you don't save any engine weight and you still add hundreds of pounds of batteries.  Unless the hull is redesigned for this weight, it will just slow you down.

I am not against electric propulsion.  We still love the fact we did it to Yumsuch.  But it has its place.  If you are a lake or bay sailor, than go for it.  If you regularly fight tidal currents and need to make miles for a safe anchorage, then don't.   If technology ever catches up, which I doubt it will for sailboats, then I will reevaluate.  

We also had one question from Bob and Brenda.  They were wondering how we charge our battery bank on Yasmine Ann.  Good question.  They saw we went from 850 Amp hour battery bank to 138 Amp hours.

In a 24 hour period, we use about 210 amp hours.  Most of that is during the day, due to the inverter being on all day for computers.  Before the Valence battery, we used between 40-60 amp hours overnight.  With the new battery, that has been reduced to 30-50 amp hours.  Higher efficiency on refrigeration compressors due to higher voltage.  The most, we have drawn out, is 63 amp hours.  Then the sun kicked in.  The Valence battery has 10,000 discharge cycles at 50%, versus 1000 for AGM.

Yasmine Ann came with 3 - 210 watt Kyocera panels.  This past summer, we added a 350 Watt Superwind wind generator.  Last year, the solar panels would have us charged by noon and keep up all day.  The same is true for this year.  However, last year, we ran the generator everyday (30 minutes) for hot water showers.  We added the Superwind to allow a 180watt DC heating element to be added to the hot water heater.  As long as the wind is blowing, or we have the right sun angles, we can heat our water with surplus "green" energy now.  I had a custom element made that screws into the drain plug fitting.  We have the element switched separately.  Two hours, gives us warm water and 4 hours gives us hot water in our 11 gallon tank.  The wind generator also allows us to get power on the cloudy, but windy days.  The wind is always blowing in the Keys.

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