The3 blade propellers we have designed for the 9,6 Kw Green Motion underwater motors are only 1.6 kilo in weight each, the blade size is .53 contrary to the more frequently used . 34 , more of a tugboat type prop , they are 18 x 18 so in fact 35 % larger than would be the case for a high rpm diesel saildrive
with a max prop rpm
of 1800 while we rotate this prop at max 900 rpm since they are out of the water
while sailing they offer no resistance at all.
These propellers are shrouded to increase the efficiency both for propulsion
and for generation with an extra 15 % coming to a efficiency of close to 60 %. to take the example of Alan 1 hour of motoring around and into the harbor or going out with the same time motoring we use around 8 KW of battery
power. when sailing along and using the underwaer motorgens for regeneration at 9 knots of speed we generate 4 Kw per side or a total of 8 Kw so it takes us 1 hour to get the batteries to the same level as when we entered or left the harbor without using any fossil fuels.
Besides generating with the underwater motogens we also install 860 watt of solar panels
on the bimini
top ( 4 x sanyyo 2 d 215 )and one new Air Breeze mast
top mounted wind generator
that gives us an average of 200 watt per hour
on average we get 10 Kw per day from solar
power , sufficient to run all systems including electric
when moored for longer periods.