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)
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.
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.
>
>
> 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).
>
>
>
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