The 47 foot, 20,000 lb. cat my numbers are from used two 12 horse engines. Running off a 10 kW
genset, it could make 7 knots. So your numbers are, typically, off by a factor of three.

Further why do you assume the boat sails out as far as it can, and then powers all the way back? Is
that what you normally do? Most people will sail back to their marine or inlet, etc. and then power
in.

--
-jeff

"JAXAshby" wrote in message ...
let's see. 2 22 hp engines running a total of 25 minutes uses (with 100%
efficiency) uses approzimatedl 13,752.345627 watts. The boat produces (at 9
knots) about 3,000 watts.

This means that with 100% efficiency that sailboat only has to make 9 knots for
just under 5 hours.

And at 9 knots for 5 hours, the boat is 45 miles away.

howya gonna git home in 10 minutes in that boat?

Sounds like a reasonable set up. Most daysailors motor 15 minutes to leave
slip, then sail a few hours, and motor 10 minutes to return to slip. Should
work well for that. And a gen-set as a back up.

Scotty

SV


"Jeff Morris" wrote in message
...
No, the regen isn't necessarily needed if you start with a topped of
battery. A
system like this gives one a lot of options. Regeneration will not
provide for
all needs, except in limited cases. However, it is nice if it can supply
a
substantial part of the use.


"JAXAshby" wrote in message
...
so, the regen doesn't really work unless you plug the batteries in at
the
dock?

okay.

but, if that is the case why buy the regen equipment?


Jaxie, you're having your typical comprehension problem. The 32
hp-hours
generated should be enough for an hour or two of powering - plenty to
power
the
cat out and back into the inlet. Since the batteries give 2 to 4 hours
of
backup, it isn't really necessary to regenerate if you're day sailing
out of
a
slip.

If you want to do long distance powering or motorsailing, you need to
run a
genset. However, a genset run at optimum rpm for recharging will be a
lot
cheaper to run than twin diesels.

"JAXAshby" wrote in message
...
let's see. 22 amps at 144 (sic) volts when sailing 18 knots, for
about 4
hp
stored per hour times 8 hours gives about 32 hp hours.

yup, that works. you sailed 144 miles and now you're going to motor
back
using
1 hp and you are going to do it in just 32 hours (actually about 20
hours
after
taking out ineffiencies).

Being a little sloppy with the units is not that bad - his real
blunder is
claiming 72 Watts output. The Condor catamaran claims 22 Amps at
144
Volts,
or
over 3 kW output when regenerating in a good breeze. They generate
enough
sailing during the day to power in and out of their inlet.


"Martin Baxter" wrote in message
...
JAXAshby wrote:
oh, you mean horsepower can not be compared to watts?

Gee, the European engine manufacturers do it all the time.
somebody
should
tell them you can't do that.

No, I mean this:

"6 amps at 12 volts for 24 hours = 1,728 watts, which = 2.3
hp-hours."

Amps times Volts times hours = Watt-hrs, a unit of energy
Horspower times hours= hp-hrs, a unit of energy
Watts are units of power
Horsepower is a unit of power (who would of thought it?)

Energy and power are two different things, which you well know.

Cheers
Marty

Jaxass doesn't sail... obviously.

"Jeff Morris" wrote in message
...
The 47 foot, 20,000 lb. cat my numbers are from used two 12 horse engines.
Running off a 10 kW
genset, it could make 7 knots. So your numbers are, typically, off by a
factor of three.

Further why do you assume the boat sails out as far as it can, and then
powers all the way back? Is
that what you normally do? Most people will sail back to their marine or
inlet, etc. and then power
in.

--
-jeff

"JAXAshby" wrote in message
...
let's see. 2 22 hp engines running a total of 25 minutes uses (with
100%
efficiency) uses approzimatedl 13,752.345627 watts. The boat produces
(at 9
knots) about 3,000 watts.

This means that with 100% efficiency that sailboat only has to make 9
knots for
just under 5 hours.

And at 9 knots for 5 hours, the boat is 45 miles away.

howya gonna git home in 10 minutes in that boat?

Sounds like a reasonable set up. Most daysailors motor 15 minutes to
leave
slip, then sail a few hours, and motor 10 minutes to return to slip.
Should
work well for that. And a gen-set as a back up.

Scotty

SV


"Jeff Morris" wrote in message
...
No, the regen isn't necessarily needed if you start with a topped of
battery. A
system like this gives one a lot of options. Regeneration will not
provide for
all needs, except in limited cases. However, it is nice if it can
supply
a
substantial part of the use.


"JAXAshby" wrote in message
...
so, the regen doesn't really work unless you plug the batteries in
at
the
dock?

okay.

but, if that is the case why buy the regen equipment?


Jaxie, you're having your typical comprehension problem. The 32
hp-hours
generated should be enough for an hour or two of powering - plenty
to
power
the
cat out and back into the inlet. Since the batteries give 2 to 4
hours
of
backup, it isn't really necessary to regenerate if you're day
sailing
out of
a
slip.

If you want to do long distance powering or motorsailing, you need
to
run a
genset. However, a genset run at optimum rpm for recharging will
be a
lot
cheaper to run than twin diesels.

"JAXAshby" wrote in message
...
let's see. 22 amps at 144 (sic) volts when sailing 18 knots,
for
about 4
hp
stored per hour times 8 hours gives about 32 hp hours.

yup, that works. you sailed 144 miles and now you're going to
motor
back
using
1 hp and you are going to do it in just 32 hours (actually about
20
hours
after
taking out ineffiencies).

Being a little sloppy with the units is not that bad - his real
blunder is
claiming 72 Watts output. The Condor catamaran claims 22 Amps
at
144
Volts,
or
over 3 kW output when regenerating in a good breeze. They
generate
enough
sailing during the day to power in and out of their inlet.


"Martin Baxter" wrote in message
...
JAXAshby wrote:
oh, you mean horsepower can not be compared to watts?

Gee, the European engine manufacturers do it all the time.
somebody
should
tell them you can't do that.

No, I mean this:

"6 amps at 12 volts for 24 hours = 1,728 watts, which = 2.3
hp-hours."

Amps times Volts times hours = Watt-hrs, a unit of energy
Horspower times hours= hp-hrs, a unit of energy
Watts are units of power
Horsepower is a unit of power (who would of thought it?)

Energy and power are two different things, which you well
know.

Cheers
Marty

so, you are going to replace 2 12 hp engines with one 15 hp engine driving a
generator (losing efficiency), which in turn drives two electric motors (losing
efficiency).

Now how in hell is that an improvement?

The 47 foot, 20,000 lb. cat my numbers are from used two 12 horse engines.
Running off a 10 kW
genset, it could make 7 knots. So your numbers are, typically, off by a
factor of three.