Jim,
(ICE or Electric) Shaft HP is only shaft HP. Measurements of power
drain don't define Shaft HP but do measure the amount of power needed to
compensate for the losses if we set up a dynamo. Large Props require
torque not available from ICE without gearing, that in itself gear
reduction has larger loss than direct drive that could in theory can be
achived using many polls and large diameters within our electric motors.
With our efforts many of these statements don't mean anything because we
are not custom building motors for our boats. But what is common is the
use of small diameter props designed to slip so ICE size can be small
with smaller reductions, allowing the ability for our ICE to reach it's
torque curve. If we design around a big prop and low RPM we will obtain
more for less on the power curve. Likely however we find that draft,
and cost, get in the way of optimal battery life.
Kevin Pemberton
On 08/18/2011 04:16 PM, luv2bsailin wrote:
> What about the assumption that Gerr truly is talking about actual
> shaft HP, and not some derived value that's based on other assumptions
> that apply to ICE and not electrics? Is that specifically stated in
> bis work? Maybe I'm being simplistic, but I gotta ask.
> Jim
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