On Nov 24, 6:50*pm, Bruce wrote:
On Wed, 24 Nov 2010 06:12:11 -0800 (PST), Joe





wrote:
On Nov 23, 4:44 am, Bruce wrote:
On Mon, 22 Nov 2010 17:49:24 -0800 (PST), Joe

wrote:
On Nov 22, 6:39 pm, Bruce wrote:
On Mon, 22 Nov 2010 08:54:03 -0800 (PST), Joe

wrote:
On Nov 22, 9:40 am, Wayne.B wrote:
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. :-)

I'm going to have to disagree with you Wayne. The amount of energy
coming off a shaft at sailing speed can be huge. The drag can be
offset by canvas with ease on a non-planing hull. If you capture 1 rpm
of energy for every 4 rmp's generated by sail, and can store that
energy you have a system that can work.

Now if a bus can capture 97% of the kinetic energy by stopping then
why can't a prop do the same ?
About the smallest CVP system available is in the high 30's low 40"
diameter.
You ever chain down a shaft to a 40" prop? You better have some strong
chain.

http://www.youtube.com/watch?v=6KSnH6DFA94Not quite a 1000 ft drop
but plenty of power to harness.

Joe

Are you normally obtuse, or have you always gotten your technical
information from the movies?

The Youtube show you recommended states that it is a 200 ton sailing
boat. While your reference doesn't indicate the length of the vessel
but seems to say that they were doing 9 knots.

I found a reference to another 200 ton sailing vessel on the net - it
was 138 feet long. The hull speed for a 138 ft. vessel is about 16
knots so your reference was sailing at abut half hull speed (56%
actually). Hardly impressive.

Hardly, but enough to spin a big prop without much concern of the drag
the prop makes..

Are you serious? I've never seen anyone who doesn't care about drag.
The largest ships in the world are certainly extremely concerned about
it and in fact that is probably the major pitch that the paint
companies have when trying to sell to those companies. The Emma Mersk
brags about their super slippery paint that saves them 1,200 tons of
fuel a year. The funny looking "bulb bow" that you see on most modern
shipping is solely to reduce drag.

No kidding Bruce. It would be a trade off of drag for energy. On
Redcloud she had a 14X14 that was always dragging but she still had no
problem getting to hull speed.

And, by the bay, how many sailing yachts have you been on that were
fitted with a 40 inch propeller?

None by the bay;0). Never been on with a CVP propellor, or cort
nozzles either. Never been on one with a bow thruster , or forward
looking sonar, or a kite drive either. Never been on a hydrofoil
bigger than a rave...but there are ones out there.

Have been on a hundred boats with 25-72 inch props and had to chain
them down many times to prevent damage to the gears. As I said the
power is massive and you had better have heavy chains and binders.

Joe

You are undoubtedly correct in that big props turn bigger load but
equally have large drag factors.

Unfortunately there is no magic. You want to generate a lot of energy
at sail boat speeds 7 - 8 knots and you are going to have a
substantial amount of drag, which, of course, slows the boat and
requires a larger prop to generate the same power, which slows the
boat......

If the hull speed is 11 kts ..it's eleven knots even with a bobulious
bow.
So lets say you have a 15% drag, you hoist 20% more canvas.

Joe

Do you really not understand what is written or is it deliberate.

I didn't say that the bulb bow increases speed, I said that it
decreased drag. Damn, it is even right up at the top of the part of my
message that you have included.

However, if you don't understand here is a quote from the Wiki, which
I might add, is freely available to anyone that cares to look.

A bulbous bow is a protruding bulb at the bow (or front) of a ship
just below the waterline. The bulb modifies the way the water flows
around the hull, reducing drag and thus increasing speed, range, fuel
efficiency, and stability. Large ships with bulbous bows generally
have a 12 to 15 percent better fuel efficiency than similar vessels
without them.
Bulbous bows have been found to be most effective under the following
conditions:
when used on hulls with waterline lengths of more than about 15 m (50
ft)
when used on long, narrow hulls
when used at speeds close to the vessel's maximum speed
These points make them a standard feature for cargo ships, naval
vessels and passenger ships, all of which are large, narrow and
usually operate within a small range of speeds close to their top
speed. On the other hand, they are virtually unknown in recreational
craft like yachts, especially sailing vessels and powerboats.
Contents [hide]

Cheers,

Brice- Hide quoted text -

- Show quoted text -

On purpose Brice,

If parasitic drag of a prop cost you no fuel then what's the issue?
They put b bow's on ships to reduce fuel costs.

The goal is zero emissions, not top speed..

Joe