On Sat, 20 Nov 2010 19:20:11 +0000, Justin C
wrote:

In article , Bruce wrote:
On Fri, 19 Nov 2010 23:34:40 +0000, Justin C
wrote:

quote
The GREEN MOTION system eliminates fossil fuel used by sailing
yachts in any way. Electrical energy is generated with the system and is
stored in batteries (lithium Iron Phosphate are optional). It will
generate sufficient energy to be used for propulsion, hot water, cooking
and all electrical equipment and navigation on board. When batteries are
fully charged or high speed is required (race) the lifted Motogens
eliminate the drag from the propulsion system and this increases the
speed of the yacht (between 5 - 15%).

Retractable Motogen
The electric retractable Motogen is new, light
weight, extremely efficient and better than any propulsion system ever
designed for yachts. Usable in all sailing yachts from 30 to 90 ft (9-30
m): monohull, catamaran or trimaran). Installation can be made inside
the hull in a monohull or on a retractable arm for multihull. 5 years of
extensive testing has been done with a ‘proof of concept’ sailing in
excess of 10.000 Nm.
/quote


URL:http://www.green-motion.com/

I suspect that the estimates of drag versus speed for the generator
propeller is highly optimistic. The best estimates I can find are that
the drag from a 3 bladed prop reduces speed by about 15%, not the 5 -
15% mentioned.

They put a small amount of current through the motors as the same time
as using them to generate, this partially compensates for the drag -
according to last month's Yachting Monthly feature.


Justin.


Perhaps I'm a cynic but it sounds like pie in the sky.

Of course if they put a small amount of current through the device,
i.e., power it, it will result in less drag. But of course it also
results in less net current generated.

Frankly it sounds very much like a perpetual motion machine.

Cheers,

Bruce

In article , Bruce wrote:
On Sat, 20 Nov 2010 19:20:11 +0000, Justin C

They put a small amount of current through the motors as the same time
as using them to generate, this partially compensates for the drag -
according to last month's Yachting Monthly feature.

Perhaps I'm a cynic but it sounds like pie in the sky.

I'm prepared to suspend belief, I'm only quoting from the article.
However, if they have achieved what the article says, then that's
something quite special.


Of course if they put a small amount of current through the device,
i.e., power it, it will result in less drag. But of course it also
results in less net current generated.

Frankly it sounds very much like a perpetual motion machine.

Not quite perpetual motion, they're only claiming that they can reduce
the drag of the props to 5% by supplying some power.

Be sceptical, if it's for real we'll hear about it from other sources
over time, even some that we trust.

Justin.

--
Justin C, by the sea.

On Sun, 21 Nov 2010 07:19:02 +0700, Bruce
wrote:

Frankly it sounds very much like a perpetual motion machine.

It's definitely not perpetual motion but it does depend on a number of
assumptions that may not hold true in the real world. Extracting
energy from spinning props is definitely possible under the right
conditions but my calculations show that the maximum power available
is relatively low, quite possibly enough to supply house loads, but
very unlikely enough to recharge a large battery bank.

On Sat, 20 Nov 2010 21:18:30 -0500, Wayne.B
wrote:

On Sun, 21 Nov 2010 07:19:02 +0700, Bruce
wrote:

Frankly it sounds very much like a perpetual motion machine.

It's definitely not perpetual motion but it does depend on a number of
assumptions that may not hold true in the real world. Extracting
energy from spinning props is definitely possible under the right
conditions but my calculations show that the maximum power available
is relatively low, quite possibly enough to supply house loads, but
very unlikely enough to recharge a large battery bank.


I knew one person who had a propeller shaft driven alternator on a 40
ft. sloop and metered it's output. He said that it produced
electricity but not much and removed it to install a propshaft driven
bilge pump - bloody great thing it was. I used to offer to chop a hole
in the hole so he could test it but he never seemed to be interested.

A second had one of those towed generators and said much the same - it
did produce electricity but he still needed to run the engine
frequently when sailing unless he was very, very careful with the
electricity. He had a vane steerer so the only "can't turn it off" he
had running would have been his GPS and maybe his nav lights, but I
doubt that he would use them off shore.

And these were blokes who did sail off shore - used to quote speed in
miles per day :-) Along shore I think it would be worse. Hopefully
anyone who tries this system keeps a big outboard on board :-(

Cheers,

Brice

On Sat, 20 Nov 2010 21:18:30 -0500, Wayne.B
wrote:

It's definitely not perpetual motion but it does depend on a number of
assumptions that may not hold true in the real world. Extracting
energy from spinning props is definitely possible under the right
conditions but my calculations show that the maximum power available
is relatively low, quite possibly enough to supply house loads, but
very unlikely enough to recharge a large battery bank.

Wayne, you hit the nail on the head as they say.

As most of you know I spent about 6 years living on solar and wind
power, and built electric cars, trikes and motorcycles. So I'm all for
renewable energy and have put my money where my mouth is. But, and a
very big BUT, there are very severe limitations as to what it can do.

You just can't get vast amounts of power from wind, sun and water
unless you take up vast amounts of space and spend vast amounts of
money. One thing that comes to mind. Recently the town here dedicated
a Windspire wind generator at the library. The wind gen and everything
else was donated by various companies in town. It's a 30 foot high
thing that maxes at 1,200 Watts. Of course, like most that figure is
with a 65 MPH wind. More like 100 Watts at the normal 15 MPH winds
here. Anyway, they stated that it should save the libray about $200 a
year in electric costs. Their normal electric bill is about $5,000 a
year!

I just had a thought that might illustrate the problem, at least as
far as propulsion goes. Instead of looking at Amps or Watts directly,
lets look at Horsepower.

1 HP is 746 Watts. Now, to charge a battery there are losses, and to
get that 1 HP there are also motor losses. So to make it easy let's
say 1 HP out is 1,000 Watts, or 1 KW, in. That's 74.6% efficientcy.

Let's further say 10 HP is what we need to power the boat at a decent
speed. In the real world, probably 5 KTs for a 30 footer. Our 30
footer with 10 HP motor has 16 golf cart batteries in series for 96
Volts and 21.6 KWH. This will give us 2 hours and 10 minutes of run
time to a flat battery bank.

Most of what I've read about using an alternator on the prop state the
output is about 10 Amps, so at 13.6 Volts this is 136 Watt Hours, or
..136 KWH. Traveling 10 hours a day gives us 1.36 KWH per day. So a 10
hour sail would let us motor for 8 minutes and 10 seconds.

One could hang a big prop down there, optimised to drive an alternator
and maybe get 50 Amps with a large reduction in speed. That would give
us about 40 minutes run time.

How about solar? If we cover that entire 30 footer in solar panels, we
should be able to get about 3,000 watts. At a cost of $15,000 plus
controller at the current $5 per watt. This will give us between 9 KWH
and 18 KWH per day, depending on latitude and season.

Sooo... We can run under power from 54 mintes to 1 hour and 48 minutes
per sunny day.

We all know air conditioners are power hogs. A 15,000 BTU marine AC
takes about 1.5 HP. So imagine generating enough power to run 6-1/2 of
your AC's. That what you need to power a 30 footer.

Rick

One of the problems using the engine propeller to turn an alternator
is that the prop pitch is all wrong.

By 90 degrees, in fact.

On Sun, 21 Nov 2010 22:49:30 -0600, CaveLamb
wrote:

One of the problems using the engine propeller to turn an alternator
is that the prop pitch is all wrong.

By 90 degrees, in fact.


It works though, witness the bloke I mentioned that had an alternator
belted to the propshaft.... just that it doesn't produce much power.

Cheers,

Brice

On Nov 22, 5:10*am, Bruce wrote:
On Sun, 21 Nov 2010 22:49:30 -0600, CaveLamb
wrote:

One of the problems using the engine propeller to turn an alternator
is that the prop pitch is all wrong.

By 90 degrees, in fact.

It works though, witness the bloke I mentioned that had an alternator
belted to the propshaft.... just that it doesn't produce much power.

Cheers,

Brice

Why not use stone wheels too Bruce, since you are talking about stone
age tech? Using a belt drive and a big alternator is not going to
capture much energy anything.

Now directly couple a motor/generator that consists of a stator
winding employing a high pole count configuration, which allows for
high copper utilization (minimizing energy loss and cost), and a
hollow rotor upon which powerful rare earth permanent magnets are
mounted on the outer circumference coupled to a variable pitch prop
system and you can pump out some serious energy. The city buses that
are using these moters claim they capture 97% of the kinetic energy
developed while stopping.

You are comparing apples to oranges.

Joe

On Mon, 22 Nov 2010 07:21:00 -0800 (PST), Joe
wrote:

Now directly couple a motor/generator that consists of a stator
winding employing a high pole count configuration, which allows for
high copper utilization (minimizing energy loss and cost), and a
hollow rotor upon which powerful rare earth permanent magnets are
mounted on the outer circumference coupled to a variable pitch prop
system and you can pump out some serious energy. The city buses that
are using these moters claim they capture 97% of the kinetic energy
developed while stopping.

Regardless of the capture mechanism, even at 100% efficiency, there is
only so much energy in a moving column of water and it is not a big
number when you are moving at sailing speeds. Now if you could get
that same column of water rolling down the side of a 1,000 ft
mountain, that's a whole different story. :-)

On Mon, 22 Nov 2010 07:21:00 -0800 (PST), Joe
wrote:

On Nov 22, 5:10*am, Bruce wrote:
On Sun, 21 Nov 2010 22:49:30 -0600, CaveLamb
wrote:

One of the problems using the engine propeller to turn an alternator
is that the prop pitch is all wrong.

By 90 degrees, in fact.

It works though, witness the bloke I mentioned that had an alternator
belted to the propshaft.... just that it doesn't produce much power.

Cheers,

Brice

Why not use stone wheels too Bruce, since you are talking about stone
age tech? Using a belt drive and a big alternator is not going to
capture much energy anything.

Now directly couple a motor/generator that consists of a stator
winding employing a high pole count configuration, which allows for
high copper utilization (minimizing energy loss and cost), and a
hollow rotor upon which powerful rare earth permanent magnets are
mounted on the outer circumference coupled to a variable pitch prop
system and you can pump out some serious energy. The city buses that
are using these moters claim they capture 97% of the kinetic energy
developed while stopping.

You are comparing apples to oranges.

Joe

How does, as you say "high copper content" decrease costs?

Cheers,

Brice