I look for the 'pertinent omission' in marketing data and hype.
Sure one can argue the 'green' attributes of such a system; but, one
surely HAS to look at the all that additional weight for the batteries
and control systems. With such a boat much deeper in the water and
dragging a three bladed fixed prop .... it HAS to take MORE overall
energy to move such a boat. The boat is now much deeper in the water
and freewheeling a gigantic prop ...... of course you now need a bigger
boat that goes slower. As far that the 'energy balance' ..... I'll
bet its a 'wash' thus no clear advantage. Batteries dont last forever
and I wouldnt want the replacement bill for such 'monsters' added to my
cruising kitty.
I'm more keen on the Pardeys 'engine' choice when it comes down to
'efficiency'.


In article , Mic
wrote:

Perpetuated Motion
Electric propulsion for boats: A century-old technology may just be
the wave of the future

LINK:

http://www.cruisingworld.com/article...ID=396&catID=0

" Advocates for diesel-electric propulsion list among its virtues that
it's clean, quiet, efficient, and requires very little maintenance.
Another advantage frequently noted in connection with the STI system
is the ability to make electricity--to "regenerate"--when the boat is
under sail."

"While internal-combustion engines are typically described by their
horsepower rating, STI's motors are named for the torque they develop.
An ST 37 puts out 37 foot-pounds of torque or 6 horsepower; Tether
recommends using it on monohulls up to 32 feet and 10 tons or to
replace diesel engines of up to 24 horsepower. An ST 74 puts out 74
foot-pounds of torque or 12 horsepower; Tether recommends using it on
monohulls up to 50 feet and 16 tons or to replace diesel engines of up
to 48 horsepower."