Diesel electric can be more efficient than diesel alone because the electric
motor is effectively a gear box and energy losses in some cases can be less
than using a mechanical transmission. It is not necessarily the case though.
In yacht sizes it would be less efficient in most cases. A hydraulic drive
would normally have less transmission loss in the range we are talking
about.
The most efficient way of using a diesel is a slow speed two stroke matched
directly to the propeller. All large ships where fuel efficiency is the
first criteria use this arrangement.
http://www.emma-maersk.com/engine/Wartsila_Sulzer_RTA96-C.htm
The reason why electric drive is used in some ships is because it allows
greater control when manoeuvring and maybe better use of space within the
ship. I.E Machinery can be placed in separated spaces on a warship or away
from passenger cabins. .
In submarines because it is the best way of using two power sources on one
shaft.
-----Original Message-----
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
On Behalf Of Eric
Sent: Tuesday, 31 August 2010 8:32 a.m.
To: electricboats@yahoogroups.com
Subject: [Electric Boats] Re: Retrofiting a classic
Sid,
You're absolutely correct. Diesel-electric has been used for many decades
and has proven to be more efficient than diesel alone. But there appears to
be a problem of scale. Do you know of any specific examples of successful
diesel-electric vehicles or vessels that weigh less than 100 tons?
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "sirdarnell" <sirdarnell@...> wrote:
>
> I keep seeing this. The military has been using diesel generators with
electric engines since the 1930s (maybe earlier) to get more range. So it
must be work. Not to mention trains, cruise ships, Ice breakers,
freighters, etc.
>
> --- In electricboats@yahoogroups.com, Daniel Michaels <nov32394@> wrote:
> >
> > Unless you are going to supplement the generator with solar and wind or
shore power I think you will get less range than by just using a diesel
engine.
> >
> > Dan
>
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