> [Original Message]
> From: Ken James <[EMAIL PROTECTED]>
> To: <[email protected]>
> Date: 7/26/2008 11:08:31 PM
> Subject: Re: [Liveaboard] Electric Power
>
>
>
> Norm of Bandersnatch wrote:
> > Ken,
> >
> > I am looking forward to the report of your prototype's voyages.
> >
> > I do suggest you find out all you can about the Island Pilot DSe Hybrid
at
> > www.dsehybrid.com
> I have little money to spend on the idea right now
> so who knows when I could install the system.
>
> But it should be noted that the guru Nigal Calder
> has sold his brand new boat to make a sister ship
> which will be powered in a very similar manner to
> that I have mentioned.
>
> There are some interesting things about that boat
> in the link you sent, but I think most small
> sailboats do not have room for 6 kw worth of solar
> panels, and do not need a 75 hp diesel.
>
Norm - I didn't mean for you to copy the design, but to mine for ideas,
mentally scaling down.
> Besides, the serial hybrid nature (electric motor
> and internal combustion engine must turn the same
> shaft at all times) of their design makes it so
> you must tie the diesel to the prop shaft so you
> then loose one of the big advantages of the design
> I favor, with the genset(s) able to be mounted
> anywhere, and the possibility of having multiple
> gensets on line at different locations as needed
> supplying prop or house loads as required.
>
Norm - Perhaps I misread the description, but I got the impression that the
boat could run on electric only, without the diesel running. I sent them
an email asking if the diesel motor was mechanically coupled to the prop
shaft or not but they have not yet responded.
> What's more such a serial design as they have does
> not fully de-couple the diesel from the prop shaft
> so does not obtain max efficiency of either the
> electric motor or the diesel.
>
Norm - It would be an easy matter to install a clutch to decouple the
diesel from the prop shaft, but I don't see how the electric motor would
have any drag if it were not energized.
> There are some strange things, as well...using the
> thrusters in regun while under diesel power to
> obtain electric power from them just makes no
> sense at all in terms of efficiency, for example.
>
Norm - I guess I just didn't get the right part of their web site and
didn't see that. I take it you mean that the traction motors can be used
as generators when the diesel is turning the props. This to me is a very
good way to generate electricity, no belts or side loads. In fact a
container ship I was crew on had just such a shaft generator around the
prop shaft (the shaft was about 6 feet in diameter). It would make wild
ac, which would be rectified, then fed to an inverter to produce 440 vac 3
phase some of which would run the many reefer boxes on board.
I have a 25 KW (derated to 20 KW for single phase operation) brushless
two-bearing alternator belt driven by the prop shaft. I installed it
mainly to generate the power needed to run my 300 amp welder by putting my
CP prop in neutral while at anchor. When not in use the belt is removed.
> I do not like using a high voltage battery bank,
> either. It makes more sense to convert the voltage
> so that the battery's can be replaced or the
> numbers of them can be changed without any
> problems (one or more get weak or short) and you
> can have more flexibility.
>
> And the claim that discharging and charging the
> battery's will not shorten their life span is hog
> wash.
>
Norm - Yes, that is the case as reported in Home Power magazine. Seems the
50% of rated capacity discharge floor for lead acid house batteries ashore
is the accepted compromise between longevity and utility. On the other
hand, a submariner on the List reported that submarines he served on
periodically discharged and recharged their propulsion batteries as per
manufacturers instructions. So I guess there is more to it.
Laptop batteries, I have read, if not used, are best left discharged for
storage.
> Overall I find the concept sound but the
> implementation suspect.
>
> Maybe it best meets their goals, but I remain
> skeptical of even that.
>
> In any case there are much better ways for this
> with a small sailboat.-Ken
>
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