Just to go off on a tangent slightly.
Assuming we have a motor sailer with a hybrid diesel of 50hp diesel , and 10hp electric .
Under sail , wouldn't we get maximum value from the electric motor , turning the large prop ?.
The motor isn't so much driving the whole show , as contributing , and instead of there being prop drag , there is prop drive .
What I envisage is an electric drive contribution for most sailing time .
Does this make sense ?.
Rob J.
From: James Lambden <james@toolboat.com>
To: electricboats@yahoogroups.com
Sent: Wed, 27 October, 2010 6:49:02 AM
Subject: Re: [Electric Boats] Propulsion Marine 5 KW Electric Drive
Dick,
That would be true. More propeller area means less propeller slip and higher efficiency.
However, you can accomplish the same thing by having a larger propeller turning slower. ( A larger propeller will require a higher reduction gear ratio )
James
On Oct 19, 2010, at 10:34 AM, Dick B. wrote:
Jim:You said:< < However, as an electric drive consumes more power, the thrust per kilowatt decreases. This is because the propeller gets less efficient the faster it turns, which is a result of more propeller slip. Also, the electric motor becomes less efficient as it creates more power.>>This would indicate that a more efficient electric drive system to power a boat would be to have several motors running at a fraction of their max output driving several peopellers turning at slower speed. Is this true?Dick
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