Thanks for the comparisons. John
On Sun, Aug 2, 2009 at 6:11 PM, Arby Bernt <arbybernt@yahoo.
>
>
> 28 tons of fuel per hour sounds like a major burn rate, until you consider
> the QEII's displacement.
> I don't have the numbers in front of me right now, but I recall it
> translating to something like 50 mpg for a passenger vehicle. Amazing,
> considering more than 50% of the energy is used to support the ship's hotel
> load.
> Locomotives use AC drive systems due to the complexity of coupling the
> engine to the drive wheels. Before AC coupling was available, the slip
> between the drive wheels and the track was nearly impossible to control, as
> the friction of a non-slipping drive wheel can transmit more force than than
> a slipping wheel. By comparing the rotation of a drive wheel to a static
> wheel, the speed difference can be maintained at under 0.5%. This allows a
> lightweight switcher to move huge strings in the railyard, a feat prevoiusly
> requiring a full sized engine with a sander (dropping sand on the rails).
> While prop slip in a boat robs power by recirculating water around the
> propeller (consider a torriod constantly turning inside out), the result
> hardly prevents forward motion.
> In many conditions, ICE's can be optimized by running at a peak effeciency
> point. This is the goal of systems like those installed in large ships, and
> now even passage making yachts (Kady-Krogen)
> Lugger) will cruise the boat at 70% of hull speed, and a second generator
> (50kW MTU) can be brought online for heavy seas and manuevering.
> Since our group tends to fall in a smaller class of boating, batteries
> become practicale for most requirements. Using a generator to run a 10kW
> system or smaller requires more complexity than a simple 7.5hp outboard, not
> to mention maintence.
> Every system has a sweet spot, determined by many factors, not just going
> green....
>
> Be Well,
> Arby
>
>
> On Aug 2, 2009, at 5:50 AM, John Delia <bzalto@gmail.
> wrote:
>
> Yes, but the 4 Diesel and 2 turbo Diesel generators burn 28 TONS of
> fuel/hour when doing 30 knots. Not very ecologically friendly, though it is
> more efficient and more maneuverable than a conventionally driven vessel
> because the two front pods rotate a full 180 degrees. John
>
> On Sat, Aug 1, 2009 at 7:41 PM, Matthew Geier <matthew@acfr.
> >wrote:
>
> >
> >
> > Myles Twete wrote:
> > >> The Queen Mary runs on electrics...
> > >>
> > >
> > >
> > >
> > > Queen Mary 2 is propelled by electric motors, but its electric energy
> is
> > > created by 4 diesel engines (67Mw total) and 2 gas turbines (50Mw
> total).
> > >
> > > Queen Mary 1 was steam powered.
> > >
> > >
> > >
> > > QM2 is a great example to point out to skeptics who think that it would
> > make
> > > no sense to have a larger boat propelled by electric motors if you'd
> need
> > a
> > > genset to create the electricity.
> > >
> > Electricity is a common 'transmission' for large haul applications. Not
> > just large ships. The world is covered with 1000s of 'diesel electric'
> > railway locomotives - from approx 1000hp up. There has to be a reason
> > why electricity is the favoured transmission for every thing from large
> > ships, railway locomotives to mining draglines and haul trucks.
> >
> > My non sailing boat is small enough and slow enough that the primary
> > energy source can be storage batteries. (Which hasn't been used for
> > months now, Winter here, and the motor/controler is inside my house, not
> > on the boat - only the batteries and the charger are still on board,
> > top-up charging at this very moment (If the charger hasn't shut off
> > already).
> >
> >
> >
>
> [Non-text portions of this message have been removed]
>
> [Non-text portions of this message have been removed]
>
>
>
[Non-text portions of this message have been removed]
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