[Electric Boats] Re: more regen conversation
Myles
Thanks for the explanation.
But which would be more efficient, turning the motor faster or slower with more resistance?
Glenn
toggle quoted message
Show quoted text
--- In electricboats@..., "Myles Twete" <matwete@...> wrote:
OOPS.I meant to say: Since the power is proportional to the speed cubed, the
prop driving 10knots of current will transfer substantially MORE power than
if it is "driven" by the water with the 5knots of water stream current in
regen (assuming efficiencies were the same both ways, which they aren't).
-mt
From: electricboats@... [mailto:electricboats@...]
On Behalf Of Myles Twete
Sent: Wednesday, December 01, 2010 11:07 AM
To: electricboats@...
Subject: RE: [Electric Boats] Re: more regen conversation
Probably the best you could do is get the same prop and conversion
efficiency as your system does in delivering electrical energy into boat
kinetic energy. So if you happen to have a damn good prop that gets 65-70%
propulsion efficiency and assuming the other electric-mechanical efficiency
is a decent 80%, we see perhaps 50% energy loss in the electric-to-kinetic
energy conversion.
Reversing this, you'd similarly expect AT BEST, a 50% return energy
efficiency of water energy delivered to the propeller in a generation mode
to your battery bank. Now, as a drive, the prop sends out a water stream
that is significantly faster than the free flow under the boat. Therefore,
cruising at say, 5knots, the water flowing thru the prop might be 8knots.
Since the power is proportional to the speed cubed, the prop driving 10knots
of current will transfer substantially less power than if it is "driven" by
the water with the 5knots of water stream current in regen (assuming
efficiencies were the same both ways, which they aren't).
So say that it takes 2kw from your batteries to cruise at 5kts.
And say that the water shoots out thru the prop at nom. 10kts to do this.
It's arguable that the best you could get in regen at 5kts with the same
prop is about 2kw*(5/10)^1/3, or 125watts.
This is optimistic depending on the prop and the boat.
But with regen we can take the boat largely out of the equation because it's
just a matter of stream flow and prop and prop loading. Someone might want
to explore this for a few typical props used on your sailboats.
-Myles Twete
From: electricboats@... [mailto:electricboats@...]
On Behalf Of Glenn Dennis
Sent: Wednesday, December 01, 2010 10:31 AM
To: electricboats@...
Subject: [Electric Boats] Re: more regen conversation
All
I was disappointed to learn that regen would not "completely solve all
problems" ;-) But as I read the last post I wondered, has anyone tried a
different ratio for regen sort of a two speed trans, one for propulsion and
one for regeneration. Wouldn't be that hard to fab up, but would it work?
I'm inclined to think not, in that there is only so much force being exerted
against the prop by the water flow.
You could get the motor to turn faster with a small resistance or the motor
to turn slower with large resistance, which would produce more power?
Thoughts?
Glenn
--- In electricboats@...
<mailto:electricboats%40yahoogroups.com> , Sally Reuther <smreuther@>
wrote:
Eric,
Thanks for adding this clear explanation concerning regen. I've found the
people who are asking us about regen under sail seem to think of this as
"free power" and that it will solve all of the charging problems. What we
know is that it's a trade off and you really need to make some choices if
you want to have regen work for you at all. Most folks want to be able to
motor as fast as possible so they make sure the gearing on their electric
systems is such that they can get optimum propulsion. If this is 5 knots
on
a boat that can only sail (because of displacement ratios) 6.5 knots, then
the window for regen is that 1.5 knots of speed. The regen does not kick in
until you get past the point where your motor is set to motor at top speed.
I'm a sailor and I know that being able to sail at my boats hull speed for
any length of time is dependent on many factors and usually doesn't happen -
especially if I am only out sailing for the day and tacking a lot. To be
able to make regen work, the top motoring speed needs to be set lower, and
you need to be able to sail for a sustained period of time at that higher,
constant speed to get anything back into the system. Even then, as you
pointed out, the numbers are not huge. I don't understand the math involved
- I'm the artist and idea person, but I do understand the basic theory as I
explained it above. Regen is a fantastic idea, it's just not the solution
to our charging problems we would love to have.
Sally
On Mon, Nov 29, 2010 at 6:52 PM, Eric <ewdysar@> wrote:
Larry,
As the most visible "regen naysayer" here, the link that you provided
completely supports my previous premise.
According to the Whoosh site "... And since we average 5-6 kts, that's
over
100 amp/hrs/day - for us quite possibly 150 amp/hrs/day - that is
available
for running the radar at night, making water with offshore water
quality,
feeding the SSB radio, and keeping the iPod charged..." So what does
this
mean? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24
hours
or 50-75W at 5-6kts. They do say that the harvested water power is
sufficicient for house loads, a statement that I wholeheartedly agree
with.
My statement is (and always has been) that regen at speeds around 5kts
is
not a viable source of charging for a traction battery bank. The speed
is
important because most displacement auxilliary sailboats between 27-32
feet
(optimal for a 5kW electric drive) have a hard time hitting sustained
runs
above 6 kts. For this size boat, average sailing speeds of about 5.5kts
is
more realistic.
So let's say that you use 4kWh of energy out of your 10kWh battery bank,
that's about 10-12nm at 4kts in most of our boats. How far would you
have to
sail using the system described by Whoosh to bring your batteries back
to
full charge, assuming that you are using no electrical power in the mean
time? Generating 75W at 6kts, that's 12.5Wh/nm. So 4kWh will take 320nm
of
sailing at 6kts and will take over 53 hours. Slow down to 5kts under
sail
and the recharge distance is up to 400nm and will take 80 hours. If you
have
a 12V house load of only 2A, the recharge times and distances double.
Ignoring house loads, the ratio of drive distance (at 4kts) to regen
distance (at 5kts) is about 1 to 40. Motor one mile at 4kts (15 minutes)
and
you need to sail 40 miles at 5kts (8 hours) to get the charge back. If
you
use a radio, autopilot or lights, the ratio gets worse.
So regen works, but is not as effective at recharging your traction
batteries as some drive vendors would like you to believe.
Fair winds,
Eric
Marina del Rey
--- In electricboats@...
<mailto:electricboats%40yahoogroups.com> <electricboats%40yahoogroups.com>,
"Larry Doyle" <ldoyle@> wrote:
Here's to those NaySayers that say regen doesn't work. Here's some
boats
that are doing it using towed gens as well as the free wheeling the
prop/dc
motor in regen mode.
www.svsarah.com/Whoosh/WhooshPacificPrepTowGenerator.html
|
[Electric Boats] Re: more regen conversation
Myles, your numbers look good. I have noticed that most prop manufacturers use a 50-55% "slip" factor in determining the proper pitch for displacement auxilliary sailboats, so your 65-70% prop efficiency may be a bit optimistic for many of our conversions.
One problem in tuning a prop to maximize regen will decrease it's drive efficiency. Since I'm personally more interested in drive efficiency to maximize my powered range, then I'm will to accept less regen. You have clearly demonstrated why regen is limited due to the different water and prop speeds, so adding 20% to regen efficiency could make a small difference, but if came at the cost of 20% drive efficiency, it looks like a losing proposition to me. Others may think differently...
Fair winds,
Eric
Marina del Rey, CA
toggle quoted message
Show quoted text
--- In electricboats@..., "Myles Twete" <matwete@...> wrote:
Probably the best you could do is get the same prop and conversion
efficiency as your system does in delivering electrical energy into boat
kinetic energy. So if you happen to have a damn good prop that gets 65-70%
propulsion efficiency and assuming the other electric-mechanical efficiency
is a decent 80%, we see perhaps 50% energy loss in the electric-to-kinetic
energy conversion.
Reversing this, you'd similarly expect AT BEST, a 50% return energy
efficiency of water energy delivered to the propeller in a generation mode
to your battery bank. Now, as a drive, the prop sends out a water stream
that is significantly faster than the free flow under the boat. Therefore,
cruising at say, 5knots, the water flowing thru the prop might be 8knots.
Since the power is proportional to the speed cubed, the prop driving 10knots
of current will transfer substantially less power than if it is "driven" by
the water with the 5knots of water stream current in regen (assuming
efficiencies were the same both ways, which they aren't).
So say that it takes 2kw from your batteries to cruise at 5kts.
And say that the water shoots out thru the prop at nom. 10kts to do this.
It's arguable that the best you could get in regen at 5kts with the same
prop is about 2kw*(5/10)^1/3, or 125watts.
This is optimistic depending on the prop and the boat.
But with regen we can take the boat largely out of the equation because it's
just a matter of stream flow and prop and prop loading. Someone might want
to explore this for a few typical props used on your sailboats.
-Myles Twete
|
Re: [Electric Boats] Re: more regen conversation
Thanks Myles, it is in prop efficiency, next the mechanical drag, and then current control.. ? I've been working on the first thing, prop efficiency.. ?Dave K
From: Myles Twete
To: electricboats@...
Sent: Wed, December 1, 2010 2:10:06 PM
Subject: RE: [Electric Boats]
Re: more regen conversation
OOPS¡I meant to say: Since the power is proportional to the speed cubed, the prop driving 10knots of current will transfer substantially MORE power than if it is ¡°driven¡± by the water with the 5knots of water stream current in regen (assuming efficiencies were the same both ways, which they aren¡¯t). ?-mt ? ? From:
electricboats@... [mailto:electricboats@...] On Behalf Of Myles Twete
Sent: Wednesday, December 01, 2010 11:07 AM
To: electricboats@...
Subject: RE: [Electric Boats] Re: more regen conversation ? ? Probably the best you could do is get the same prop and conversion efficiency as your system does in delivering electrical energy into boat kinetic energy.? So if you happen to have a damn good prop that gets 65-70% propulsion efficiency and assuming the other electric-mechanical efficiency is a decent 80%, we see perhaps 50% energy loss in the electric-to-kinetic energy conversion. Reversing this, you¡¯d similarly
expect AT BEST, a 50% return energy efficiency of water energy delivered to the propeller in a generation mode to your battery bank.? Now, as a drive, the prop sends out a water stream that is significantly faster than the free flow under the boat.? Therefore, cruising at say, 5knots, the water flowing thru the prop might be 8knots.? Since the power is proportional to the speed cubed, the prop driving 10knots of current will transfer substantially less power than if it is ¡°driven¡± by the water with the 5knots of water stream current in regen (assuming efficiencies were the same both ways, which they aren¡¯t). ? So say that it takes 2kw from your batteries to cruise at 5kts. And say that the water shoots out thru the prop at nom.
10kts to do this. It¡¯s arguable that the best you could get in regen at 5kts with the same prop is about 2kw*(5/10)^1/3, or 125watts. This is optimistic depending on the prop and the boat. But with regen we can take the boat largely out of the equation because it¡¯s just a matter of stream flow and prop and prop loading.? Someone might want to explore this for a few typical props used on your sailboats. ? ? -Myles Twete ? From: electricboats@... [mailto:electricboats@...] On Behalf Of Glenn Dennis
Sent: Wednesday, December 01, 2010 10:31 AM
To: electricboats@...
Subject: [Electric Boats] Re: more regen conversation ? ? All
I was disappointed to learn that regen would not "completely solve all problems" ;-) But as I read the last post I wondered, has anyone tried a different ratio for regen sort of a two speed trans, one for propulsion and one for regeneration. Wouldn't be that hard to fab up, but would it work? I'm inclined to think not, in that there
is only so much force being exerted against the prop by the water flow.
You could get the motor to turn faster with a small resistance or the motor to turn slower with large resistance, which would produce more power?
Thoughts?
Glenn
--- In electricboats@..., Sally Reuther <smreuther@...> wrote:
>
> Eric,
>
> Thanks for adding this clear explanation concerning regen. I've found the
> people who are asking us about regen under sail seem to think of this as
> "free power" and that it will solve all of the charging problems. What we
> know is that it's a trade off and you really need to make some choices if
> you want to have regen work for you at all. Most folks want to be able to
> motor as fast as possible so they make sure
the gearing on their electric
> systems is such that they can get optimum propulsion. If this is 5 knots on
> a boat that can only sail (because of displacement ratios) 6.5 knots, then
> the window for regen is that 1.5 knots of speed. The regen does not kick in
> until you get past the point where your motor is set to motor at top speed.
> I'm a sailor and I know that being able to sail at my boats hull speed for
> any length of time is dependent on many factors and usually doesn't happen -
> especially if I am only out sailing for the day and tacking a lot. To be
> able to make regen work, the top motoring speed needs to be set lower, and
> you need to be able to sail for a sustained period of time at that higher,
> constant speed to get anything back into the system. Even then, as you
> pointed out, the numbers are not huge. I don't understand the math involved
> - I'm the artist
and idea person, but I do understand the basic theory as I
> explained it above. Regen is a fantastic idea, it's just not the solution
> to our charging problems we would love to have.
>
> Sally
>
> On Mon, Nov 29, 2010 at 6:52 PM, Eric wrote:
>
> >
> >
> > Larry,
> >
> > As the most visible "regen naysayer" here, the link that you provided
> > completely supports my previous premise.
> >
> > According to the Whoosh site "... And since we average 5-6 kts, that's over
> > 100 amp/hrs/day ¨C for us quite possibly 150 amp/hrs/day ¨C that is available
> > for running the radar at night, making water with offshore water quality,
> > feeding the SSB radio, and keeping the iPod charged..." So what does this
> > mean? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24
hours
> > or 50-75W at 5-6kts. They do say that the harvested water power is
> > sufficicient for house loads, a statement that I wholeheartedly agree with.
> >
> > My statement is (and always has been) that regen at speeds around 5kts is
> > not a viable source of charging for a traction battery bank. The speed is
> > important because most displacement auxilliary sailboats between 27-32 feet
> > (optimal for a 5kW electric drive) have a hard time hitting sustained runs
> > above 6 kts. For this size boat, average sailing speeds of about 5.5kts is
> > more realistic.
> >
> > So let's say that you use 4kWh of energy out of your 10kWh battery bank,
> > that's about 10-12nm at 4kts in most of our boats. How far would you have to
> > sail using the system described by Whoosh to bring your batteries back to
> > full charge, assuming
that you are using no electrical power in the mean
> > time? Generating 75W at 6kts, that's 12.5Wh/nm. So 4kWh will take 320nm of
> > sailing at 6kts and will take over 53 hours. Slow down to 5kts under sail
> > and the recharge distance is up to 400nm and will take 80 hours. If you have
> > a 12V house load of only 2A, the recharge times and distances double.
> >
> > Ignoring house loads, the ratio of drive distance (at 4kts) to regen
> > distance (at 5kts) is about 1 to 40. Motor one mile at 4kts (15 minutes) and
> > you need to sail 40 miles at 5kts (8 hours) to get the charge back. If you
> > use a radio, autopilot or lights, the ratio gets worse.
> >
> > So regen works, but is not as effective at recharging your traction
> > batteries as some drive vendors would like you to believe.
> >
> > Fair winds,
> >
Eric
> > Marina del Rey
> >
> > --- In electricboats@... ,
> > "Larry Doyle" wrote:
> > >
> > > Here's to those NaySayers that say regen doesn't work. Here's some boats
> > that are doing it using towed gens as well as the free wheeling the prop/dc
> > motor in regen mode.
> > >
> > >
> > >
> >
> >
> >
>
|
Re: [Electric Boats] Re: more regen conversation
OOPS¡I meant to say: Since the power is proportional to the speed cubed, the prop driving 10knots of current will transfer substantially MORE power than if it is ¡°driven¡± by the water with the 5knots of water stream current in regen (assuming efficiencies were the same both ways, which they aren¡¯t). ?-mt ? ?
toggle quoted message
Show quoted text
From: electricboats@... [mailto:electricboats@...] On Behalf Of Myles Twete
Sent: Wednesday, December 01, 2010 11:07 AM
To: electricboats@...
Subject: RE: [Electric Boats] Re: more regen conversation? ? Probably the best you could do is get the same prop and conversion efficiency as your system does in delivering electrical energy into boat kinetic energy.? So if you happen to have a damn good prop that gets 65-70% propulsion efficiency and assuming the other electric-mechanical efficiency is a decent 80%, we see perhaps 50% energy loss in the electric-to-kinetic energy conversion. Reversing this, you¡¯d similarly expect AT BEST, a 50% return energy efficiency of water energy delivered to the propeller in a generation mode to your battery bank.? Now, as a drive, the prop sends out a water stream that is significantly faster than the free flow under the boat.? Therefore, cruising at say, 5knots, the water flowing thru the prop might be 8knots.? Since the power is proportional to the speed cubed, the prop driving 10knots of current will transfer substantially less power than if it is ¡°driven¡± by the water with the 5knots of water stream current in regen (assuming efficiencies were the same both ways, which they aren¡¯t). ? So say that it takes 2kw from your batteries to cruise at 5kts. And say that the water shoots out thru the prop at nom. 10kts to do this. It¡¯s arguable that the best you could get in regen at 5kts with the same prop is about 2kw*(5/10)^1/3, or 125watts. This is optimistic depending on the prop and the boat. But with regen we can take the boat largely out of the equation because it¡¯s just a matter of stream flow and prop and prop loading.? Someone might want to explore this for a few typical props used on your sailboats. ? ? -Myles Twete ? From: electricboats@... [mailto:electricboats@...] On Behalf Of Glenn Dennis
Sent: Wednesday, December 01, 2010 10:31 AM
To: electricboats@...
Subject: [Electric Boats] Re: more regen conversation ? ? All
I was disappointed to learn that regen would not "completely solve all problems" ;-) But as I read the last post I wondered, has anyone tried a different ratio for regen sort of a two speed trans, one for propulsion and one for regeneration. Wouldn't be that hard to fab up, but would it work? I'm inclined to think not, in that there is only so much force being exerted against the prop by the water flow.
You could get the motor to turn faster with a small resistance or the motor to turn slower with large resistance, which would produce more power?
Thoughts?
Glenn
--- In electricboats@..., Sally Reuther wrote:
>
> Eric,
>
> Thanks for adding this clear explanation concerning regen. I've found the
> people who are asking us about regen under sail seem to think of this as
> "free power" and that it will solve all of the charging problems. What we
> know is that it's a trade off and you really need to make some choices if
> you want to have regen work for you at all. Most folks want to be able to
> motor as fast as possible so they make sure the gearing on their electric
> systems is such that they can get optimum propulsion. If this is 5 knots on
> a boat that can only sail (because of displacement ratios) 6.5 knots, then
> the window for regen is that 1.5 knots of speed. The regen does not kick in
> until you get past the point where your motor is set to motor at top speed.
> I'm a sailor and I know that being able to sail at my boats hull speed for
> any length of time is dependent on many factors and usually doesn't happen -
> especially if I am only out sailing for the day and tacking a lot. To be
> able to make regen work, the top motoring speed needs to be set lower, and
> you need to be able to sail for a sustained period of time at that higher,
> constant speed to get anything back into the system. Even then, as you
> pointed out, the numbers are not huge. I don't understand the math involved
> - I'm the artist and idea person, but I do understand the basic theory as I
> explained it above. Regen is a fantastic idea, it's just not the solution
> to our charging problems we would love to have.
>
> Sally
>
> On Mon, Nov 29, 2010 at 6:52 PM, Eric wrote:
>
> >
> >
> > Larry,
> >
> > As the most visible "regen naysayer" here, the link that you provided
> > completely supports my previous premise.
> >
> > According to the Whoosh site "... And since we average 5-6 kts, that's over
> > 100 amp/hrs/day ¨C for us quite possibly 150 amp/hrs/day ¨C that is available
> > for running the radar at night, making water with offshore water quality,
> > feeding the SSB radio, and keeping the iPod charged..." So what does this
> > mean? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24 hours
> > or 50-75W at 5-6kts. They do say that the harvested water power is
> > sufficicient for house loads, a statement that I wholeheartedly agree with.
> >
> > My statement is (and always has been) that regen at speeds around 5kts is
> > not a viable source of charging for a traction battery bank. The speed is
> > important because most displacement auxilliary sailboats between 27-32 feet
> > (optimal for a 5kW electric drive) have a hard time hitting sustained runs
> > above 6 kts. For this size boat, average sailing speeds of about 5.5kts is
> > more realistic.
> >
> > So let's say that you use 4kWh of energy out of your 10kWh battery bank,
> > that's about 10-12nm at 4kts in most of our boats. How far would you have to
> > sail using the system described by Whoosh to bring your batteries back to
> > full charge, assuming that you are using no electrical power in the mean
> > time? Generating 75W at 6kts, that's 12.5Wh/nm. So 4kWh will take 320nm of
> > sailing at 6kts and will take over 53 hours. Slow down to 5kts under sail
> > and the recharge distance is up to 400nm and will take 80 hours. If you have
> > a 12V house load of only 2A, the recharge times and distances double.
> >
> > Ignoring house loads, the ratio of drive distance (at 4kts) to regen
> > distance (at 5kts) is about 1 to 40. Motor one mile at 4kts (15 minutes) and
> > you need to sail 40 miles at 5kts (8 hours) to get the charge back. If you
> > use a radio, autopilot or lights, the ratio gets worse.
> >
> > So regen works, but is not as effective at recharging your traction
> > batteries as some drive vendors would like you to believe.
> >
> > Fair winds,
> > Eric
> > Marina del Rey
> >
> > --- In electricboats@... ,
> > "Larry Doyle" wrote:
> > >
> > > Here's to those NaySayers that say regen doesn't work. Here's some boats
> > that are doing it using towed gens as well as the free wheeling the prop/dc
> > motor in regen mode.
> > >
> > > www.svsarah.com/Whoosh/WhooshPacificPrepTowGenerator.html
> > >
> >
> >
> >
>
|
Re: [Electric Boats] Re: more regen conversation
Probably the best you could do is get the same prop and conversion efficiency as your system does in delivering electrical energy into boat kinetic energy.? So if you happen to have a damn good prop that gets 65-70% propulsion efficiency and assuming the other electric-mechanical efficiency is a decent 80%, we see perhaps 50% energy loss in the electric-to-kinetic energy conversion. Reversing this, you¡¯d similarly expect AT BEST, a 50% return energy efficiency of water energy delivered to the propeller in a generation mode to your battery bank.? Now, as a drive, the prop sends out a water stream that is significantly faster than the free flow under the boat.? Therefore, cruising at say, 5knots, the water flowing thru the prop might be 8knots.? Since the power is proportional to the speed cubed, the prop driving 10knots of current will transfer substantially less power than if it is ¡°driven¡± by the water with the 5knots of water stream current in regen (assuming efficiencies were the same both ways, which they aren¡¯t). ? So say that it takes 2kw from your batteries to cruise at 5kts. And say that the water shoots out thru the prop at nom. 10kts to do this. It¡¯s arguable that the best you could get in regen at 5kts with the same prop is about 2kw*(5/10)^1/3, or 125watts. This is optimistic depending on the prop and the boat. But with regen we can take the boat largely out of the equation because it¡¯s just a matter of stream flow and prop and prop loading.? Someone might want to explore this for a few typical props used on your sailboats. ? ? -Myles Twete ?
toggle quoted message
Show quoted text
From: electricboats@... [mailto:electricboats@...] On Behalf Of Glenn Dennis
Sent: Wednesday, December 01, 2010 10:31 AM
To: electricboats@...
Subject: [Electric Boats] Re: more regen conversation? ? All
I was disappointed to learn that regen would not "completely solve all problems" ;-) But as I read the last post I wondered, has anyone tried a different ratio for regen sort of a two speed trans, one for propulsion and one for regeneration. Wouldn't be that hard to fab up, but would it work? I'm inclined to think not, in that there is only so much force being exerted against the prop by the water flow.
You could get the motor to turn faster with a small resistance or the motor to turn slower with large resistance, which would produce more power?
Thoughts?
Glenn
--- In electricboats@..., Sally Reuther wrote:
>
> Eric,
>
> Thanks for adding this clear explanation concerning regen. I've found the
> people who are asking us about regen under sail seem to think of this as
> "free power" and that it will solve all of the charging problems. What we
> know is that it's a trade off and you really need to make some choices if
> you want to have regen work for you at all. Most folks want to be able to
> motor as fast as possible so they make sure the gearing on their electric
> systems is such that they can get optimum propulsion. If this is 5 knots on
> a boat that can only sail (because of displacement ratios) 6.5 knots, then
> the window for regen is that 1.5 knots of speed. The regen does not kick in
> until you get past the point where your motor is set to motor at top speed.
> I'm a sailor and I know that being able to sail at my boats hull speed for
> any length of time is dependent on many factors and usually doesn't happen -
> especially if I am only out sailing for the day and tacking a lot. To be
> able to make regen work, the top motoring speed needs to be set lower, and
> you need to be able to sail for a sustained period of time at that higher,
> constant speed to get anything back into the system. Even then, as you
> pointed out, the numbers are not huge. I don't understand the math involved
> - I'm the artist and idea person, but I do understand the basic theory as I
> explained it above. Regen is a fantastic idea, it's just not the solution
> to our charging problems we would love to have.
>
> Sally
>
> On Mon, Nov 29, 2010 at 6:52 PM, Eric wrote:
>
> >
> >
> > Larry,
> >
> > As the most visible "regen naysayer" here, the link that you provided
> > completely supports my previous premise.
> >
> > According to the Whoosh site "... And since we average 5-6 kts, that's over
> > 100 amp/hrs/day ¨C for us quite possibly 150 amp/hrs/day ¨C that is available
> > for running the radar at night, making water with offshore water quality,
> > feeding the SSB radio, and keeping the iPod charged..." So what does this
> > mean? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24 hours
> > or 50-75W at 5-6kts. They do say that the harvested water power is
> > sufficicient for house loads, a statement that I wholeheartedly agree with.
> >
> > My statement is (and always has been) that regen at speeds around 5kts is
> > not a viable source of charging for a traction battery bank. The speed is
> > important because most displacement auxilliary sailboats between 27-32 feet
> > (optimal for a 5kW electric drive) have a hard time hitting sustained runs
> > above 6 kts. For this size boat, average sailing speeds of about 5.5kts is
> > more realistic.
> >
> > So let's say that you use 4kWh of energy out of your 10kWh battery bank,
> > that's about 10-12nm at 4kts in most of our boats. How far would you have to
> > sail using the system described by Whoosh to bring your batteries back to
> > full charge, assuming that you are using no electrical power in the mean
> > time? Generating 75W at 6kts, that's 12.5Wh/nm. So 4kWh will take 320nm of
> > sailing at 6kts and will take over 53 hours. Slow down to 5kts under sail
> > and the recharge distance is up to 400nm and will take 80 hours. If you have
> > a 12V house load of only 2A, the recharge times and distances double.
> >
> > Ignoring house loads, the ratio of drive distance (at 4kts) to regen
> > distance (at 5kts) is about 1 to 40. Motor one mile at 4kts (15 minutes) and
> > you need to sail 40 miles at 5kts (8 hours) to get the charge back. If you
> > use a radio, autopilot or lights, the ratio gets worse.
> >
> > So regen works, but is not as effective at recharging your traction
> > batteries as some drive vendors would like you to believe.
> >
> > Fair winds,
> > Eric
> > Marina del Rey
> >
> > --- In electricboats@... ,
> > "Larry Doyle" wrote:
> > >
> > > Here's to those NaySayers that say regen doesn't work. Here's some boats
> > that are doing it using towed gens as well as the free wheeling the prop/dc
> > motor in regen mode.
> > >
> > > www.svsarah.com/Whoosh/WhooshPacificPrepTowGenerator.html
> > >
> >
> >
> >
>
|
Evergreen Solar Receives Certification Qualifying String Ribbon(R) Solar Panels for UK Solar Market
?
9:00 AM ET 11/23/10 | BusinessWire
Evergreen Solar, Inc. (NasdaqGM: ESLR), a manufacturer of String Ribbon(R) solar panels with its proprietary silicon wafer technology, today announced it has received the Microgeneration Certification Scheme (MCS) certificate from the United Kingdom's British Board of Agrement, qualifying the company's ES-A series panels for solar projects supported by the Renewables Cash-Back Scheme.
The 'Renewables Cash-Back Scheme' has been active in the UK since April 2010. Homeowners and communities who install low carbon electricity, including solar panels, are paid for the electricity they generate, even if they use it themselves. Solar projects are required to use MCS certified panels installed by MCS accredited installers to be eligible for funding.
|
[Electric Boats] Re: more regen conversation
All
I was disappointed to learn that regen would not "completely solve all problems" ;-) But as I read the last post I wondered, has anyone tried a different ratio for regen sort of a two speed trans, one for propulsion and one for regeneration. Wouldn't be that hard to fab up, but would it work? I'm inclined to think not, in that there is only so much force being exerted against the prop by the water flow.
You could get the motor to turn faster with a small resistance or the motor to turn slower with large resistance, which would produce more power?
Thoughts?
Glenn
toggle quoted message
Show quoted text
--- In electricboats@..., Sally Reuther <smreuther@...> wrote:
Eric,
Thanks for adding this clear explanation concerning regen. I've found the
people who are asking us about regen under sail seem to think of this as
"free power" and that it will solve all of the charging problems. What we
know is that it's a trade off and you really need to make some choices if
you want to have regen work for you at all. Most folks want to be able to
motor as fast as possible so they make sure the gearing on their electric
systems is such that they can get optimum propulsion. If this is 5 knots on
a boat that can only sail (because of displacement ratios) 6.5 knots, then
the window for regen is that 1.5 knots of speed. The regen does not kick in
until you get past the point where your motor is set to motor at top speed.
I'm a sailor and I know that being able to sail at my boats hull speed for
any length of time is dependent on many factors and usually doesn't happen -
especially if I am only out sailing for the day and tacking a lot. To be
able to make regen work, the top motoring speed needs to be set lower, and
you need to be able to sail for a sustained period of time at that higher,
constant speed to get anything back into the system. Even then, as you
pointed out, the numbers are not huge. I don't understand the math involved
- I'm the artist and idea person, but I do understand the basic theory as I
explained it above. Regen is a fantastic idea, it's just not the solution
to our charging problems we would love to have.
Sally
On Mon, Nov 29, 2010 at 6:52 PM, Eric <ewdysar@...> wrote:
Larry,
As the most visible "regen naysayer" here, the link that you provided
completely supports my previous premise.
According to the Whoosh site "... And since we average 5-6 kts, that's over
100 amp/hrs/day ¨C for us quite possibly 150 amp/hrs/day ¨C that is available
for running the radar at night, making water with offshore water quality,
feeding the SSB radio, and keeping the iPod charged..." So what does this
mean? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24 hours
or 50-75W at 5-6kts. They do say that the harvested water power is
sufficicient for house loads, a statement that I wholeheartedly agree with.
My statement is (and always has been) that regen at speeds around 5kts is
not a viable source of charging for a traction battery bank. The speed is
important because most displacement auxilliary sailboats between 27-32 feet
(optimal for a 5kW electric drive) have a hard time hitting sustained runs
above 6 kts. For this size boat, average sailing speeds of about 5.5kts is
more realistic.
So let's say that you use 4kWh of energy out of your 10kWh battery bank,
that's about 10-12nm at 4kts in most of our boats. How far would you have to
sail using the system described by Whoosh to bring your batteries back to
full charge, assuming that you are using no electrical power in the mean
time? Generating 75W at 6kts, that's 12.5Wh/nm. So 4kWh will take 320nm of
sailing at 6kts and will take over 53 hours. Slow down to 5kts under sail
and the recharge distance is up to 400nm and will take 80 hours. If you have
a 12V house load of only 2A, the recharge times and distances double.
Ignoring house loads, the ratio of drive distance (at 4kts) to regen
distance (at 5kts) is about 1 to 40. Motor one mile at 4kts (15 minutes) and
you need to sail 40 miles at 5kts (8 hours) to get the charge back. If you
use a radio, autopilot or lights, the ratio gets worse.
So regen works, but is not as effective at recharging your traction
batteries as some drive vendors would like you to believe.
Fair winds,
Eric
Marina del Rey
--- In electricboats@... <electricboats%40yahoogroups.com>,
"Larry Doyle" <ldoyle@> wrote:
Here's to those NaySayers that say regen doesn't work. Here's some boats
that are doing it using towed gens as well as the free wheeling the prop/dc
motor in regen mode.
www.svsarah.com/Whoosh/WhooshPacificPrepTowGenerator.html
|
Re: EPA calculated the Leaf's fuel economy based on a formula that says 33.7 kilowat
That's the same number that we use here because it is a basic scientific conversion. Gasoline holds 33.7kWh (115,000 Btu) per gallon and deisel holds 38.2kWh (130,500 Btu) per gallon.
The numbers that the EPA posted about the Leaf also suports another general conversion rule that we use here. Internal Combustion Engines (ICE) operate at about 25-30% thermal efficiency, which means that 25-30% of the energy in the fuel is available as crankshaft power. Electric drives like we use in our conversion operate at around 80-85% thermal efficiency, or about 3 times more efficient than an ICE.
The Versa averages about 33MPG as an ICE and the EPA says that the Leaf averages 99MPG as an electric or about 3 times as efficient.
This means that in general terms, 11kWh of electricity through an electric drive is roughly equivalent to 33kWh (1 gallon) through an ICE.
These are just general estimates, you can drive deeper and find specific conversion values comparing specific systems, but as a general rule of thumb, these conversions hold up across the board. Apparently even in the automotive world. :)
Fair winds,
Eric
Marina del Rey, CA
PS. I was pleased when the EPA published those numbers because they validated the work that has been done by various people on this board.
toggle quoted message
Show quoted text
--- In electricboats@..., "akenai" <akenai@...> wrote:
EPA calculated the Leaf's fuel economy based on a formula that says 33.7 kilowatts per hour holds the energy equivalent of one gallon of gasoline...
Interesting
Aaron
|
Re: [Electric Boats] EPA calculated the Leaf's fuel economy based on a formula that says 33.7 kilowat
The problem with all the data being published about
the "new" electric cars is putting it into meaningful context.? For
instance, the statement that 1 gal gas is the energy equivalent of 34 KWh is
true but mostly irrelevant when talking about cars.? An electric car wastes
about 10-15% of its energy as heat; an ICE wastes about 60-70% as heat.?
That means that 34 KWh will drive your electric vehicle as far as 3-4 gal of
gasoline.
?
The?Leaf?advertisement gets?to the
heart of fuel economy comparison?by showing miles per dollar of
fuel.
?
Denny
?
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, December 01, 2010 3:11
AM
Subject: [Electric Boats] EPA calculated
the Leaf's fuel economy based on a formula that says 33.7 kilowat
?
EPA calculated the Leaf's fuel economy based on a formula that says 33.7
kilowatts per hour holds the energy equivalent of one gallon of gasoline. The
label estimates a charging time of 7 hours on a 240-volt charge. Cost
estimates were based on 15,000 miles per year at 12 cents per
kilowatt-hour
Interesting
Aaron
|
Re: [Electric Boats] Re: more regen conversation
Eric,
Thanks for adding this clear explanation concerning regen. ?I've found the people who are asking us about regen under sail seem to think of this as "free power" and that it will solve all of the charging problems. ?What we know is that it's a trade off and you really need to make some choices if you want to have regen work for you at all. ?Most folks want to be able to motor as fast as possible so they make sure the gearing on their electric systems is such that they can get optimum propulsion. If this is 5 knots on a boat that can only sail (because of displacement ratios) 6.5 knots, then the window for regen is that 1.5 knots of speed. ?The regen does not kick in until you get past the point where your motor is set to motor at top speed. ?I'm a sailor and I know that being able to sail at my boats hull speed for any length of time is dependent on many factors and usually doesn't happen - especially if I am only out sailing for the day and tacking a lot. ?To be able to make regen work, the top motoring speed needs to be set lower, and you need to be able to sail for a sustained period of time at that higher, constant speed to get anything back into the system. ?Even then, as you pointed out, the numbers are not huge. ?I don't understand the math involved - I'm the artist and idea person, but I do understand the basic theory as I explained it above. ?Regen is a fantastic idea, it's just not the solution to our charging problems we would love to have. ?
Sally
On Mon, Nov 29, 2010 at 6:52 PM, Eric <ewdysar@...> wrote:
?
Larry,
As the most visible "regen naysayer" here, the link that you provided completely supports my previous premise.
According to the Whoosh site "... And since we average 5-6 kts, that's over 100 amp/hrs/day ¨C for us quite possibly 150 amp/hrs/day ¨C that is available for running the radar at night, making water with offshore water quality, feeding the SSB radio, and keeping the iPod charged..." So what does this mean? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24 hours or 50-75W at 5-6kts. They do say that the harvested water power is sufficicient for house loads, a statement that I wholeheartedly agree with.
My statement is (and always has been) that regen at speeds around 5kts is not a viable source of charging for a traction battery bank. The speed is important because most displacement auxilliary sailboats between 27-32 feet (optimal for a 5kW electric drive) have a hard time hitting sustained runs above 6 kts. For this size boat, average sailing speeds of about 5.5kts is more realistic.
So let's say that you use 4kWh of energy out of your 10kWh battery bank, that's about 10-12nm at 4kts in most of our boats. How far would you have to sail using the system described by Whoosh to bring your batteries back to full charge, assuming that you are using no electrical power in the mean time? Generating 75W at 6kts, that's 12.5Wh/nm. So 4kWh will take 320nm of sailing at 6kts and will take over 53 hours. Slow down to 5kts under sail and the recharge distance is up to 400nm and will take 80 hours. If you have a 12V house load of only 2A, the recharge times and distances double.
Ignoring house loads, the ratio of drive distance (at 4kts) to regen distance (at 5kts) is about 1 to 40. Motor one mile at 4kts (15 minutes) and you need to sail 40 miles at 5kts (8 hours) to get the charge back. If you use a radio, autopilot or lights, the ratio gets worse.
So regen works, but is not as effective at recharging your traction batteries as some drive vendors would like you to believe.
Fair winds,
Eric
Marina del Rey
--- In electricboats@..., "Larry Doyle" wrote:
>
> Here's to those NaySayers that say regen doesn't work. Here's some boats that are doing it using towed gens as well as the free wheeling the prop/dc motor in regen mode.
>
>
>
|
EPA calculated the Leaf's fuel economy based on a formula that says 33.7 kilowat
EPA calculated the Leaf's fuel economy based on a formula that says 33.7 kilowatts per hour holds the energy equivalent of one gallon of gasoline. The label estimates a charging time of 7 hours on a 240-volt charge. Cost estimates were based on 15,000 miles per year at 12 cents per kilowatt-hour
Interesting
Aaron
|
Re: [Electric Boats] Re: Stiletto conversion
Thanks, I promise I'll do my homework first and after sailing her silly I'll had the weight and see how she sails. ? ?I think even moving the weight around to different areas might help. ? I'm a tester, love to test and sea what's the best, something to the determent of finishing but I seem to get things done at my pace.. ?Dave K
From: Richard Mair
To:
electricboats@...
Sent: Tue, November 30, 2010 6:30:36 PM
Subject: Re: [Electric Boats] Re: Stiletto conversion
You could try just adding the weight of the batteries first before taking the plunge
Richard.
|
--- On Tue, 11/30/10, Dave Kellogg wrote:
From: Dave Kellogg
Subject: Re: [Electric Boats] Re: Stiletto conversion
To: electricboats@...
Received: Tuesday, November 30, 2010, 2:13 PM
?
Eric, ?I do know what you are talking about poundage wise and I plan on sailing myself silly just the way she is before making any significant changes... ?I've got an 8 hp Johnson 2 stroke right now and a 3 gal tank... ? ?if I go electric and I probably will it will be with a LiPo pack and an Etek, I have 4 motors to choose from, 3 brush and 1 brushless. ? I don't run around any more, don't drink or spend time chasing things that I know I don't want so I spend my money on the passions that I have, sailing and electric projects.. ?got to love what you're doing... ? ?This stiletto 26 is a conversion built by one of the engineers wanting to make a week long camping, beach-able cat with sleep aboard capabilities... ?The design never took off ?but the boat is solid and I like it, with a few astatic
changes it could
be a great looking boat, so far the performance is good but I haven't really pushed her. ? I am in the process of building a new boom because I picked up an F24 mainsail the other day and I need 12 Ft and only have 10 on the boom... ?should be fun with that roachie monster on board.. ? I also have a 20 meter sailkite that I want to try, have you ever seen one of these on a boat first hand? ? ?I've seen them on Utube, actually on a 24 tri in Hawaii.... ? Dave K ? Thanks for the welcome to the fast side of the tracks.. ?chuckle
--- On Tue, 11/30/10, Eric wrote:
From: Eric
Subject: [Electric Boats] Re: Stiletto conversion
To: electricboats@...
Date: Tuesday, November 30, 2010, 1:33 PM
I
couldn't find any specs for a Stiletto 26 but the 27's range from 1100 pounds for the base model to the 27SE at 1550 pounds.? Coming from a mono, you probably won't mind sacrificing the 22kt top speed, but you will find that these boats don't handle extra weight very well.? This includes tacking and regular sailing.
I know I've said similar things before, but imagine your boat with a regular engine (a less than 10hp outboard in your case) and a gas tank that only holds one gallon.? Convert the drive to electric and the one gallon gas tank weighs more than 500 pounds in AGM or FLA batteries.? Cut the weight in half and the tank gets reduced by about 60% due to Peukert's Effect.? So for the weight of a fairly hefty crewman, you get the equivalent of a little more than 6 cups of gas.
If that is OK, great.? I only bring this up so that you can understand the tradeoff.? I suggest that you sail the boat as is,
before you convert it, just to get a feel for a performance multi.
One of the original proponents for ULDB boats, Bill Lee, said it best, "Fast is Fun!" and I have observed that lighter is faster.? Welcome to the dark side....
Fair winds,
Eric
Marina del Rey, CA
|
|
Re: [Electric Boats] Re: Stiletto conversion
You could try just adding the weight of the batteries first before taking the plunge
Richard.
|
--- On Tue, 11/30/10, Dave Kellogg wrote:
From: Dave Kellogg
Subject: Re: [Electric Boats] Re: Stiletto conversion
To: electricboats@...
Received: Tuesday, November 30, 2010, 2:13 PM
?
Eric, ?I do know what you are talking about poundage wise and I plan on sailing myself silly just the way she is before making any significant changes... ?I've got an 8 hp Johnson 2 stroke right now and a 3 gal tank... ? ?if I go electric and I probably will it will be with a LiPo pack and an Etek, I have 4 motors to choose from, 3 brush and 1 brushless. ? I don't run around any more, don't drink or spend time chasing things that I know I don't want so I spend my money on the passions that I have, sailing and electric projects.. ?got to love what you're doing... ? ?This stiletto 26 is a conversion built by one of the engineers wanting to make a week long camping, beach-able cat with sleep aboard capabilities... ?The design never took off ?but the boat is solid and I like it, with a few astatic
changes it could
be a great looking boat, so far the performance is good but I haven't really pushed her. ? I am in the process of building a new boom because I picked up an F24 mainsail the other day and I need 12 Ft and only have 10 on the boom... ?should be fun with that roachie monster on board.. ? I also have a 20 meter sailkite that I want to try, have you ever seen one of these on a boat first hand? ? ?I've seen them on Utube, actually on a 24 tri in Hawaii.... ? Dave K ? Thanks for the welcome to the fast side of the tracks.. ?chuckle
--- On Tue, 11/30/10, Eric wrote:
From: Eric
Subject: [Electric Boats] Re: Stiletto conversion
To: electricboats@...
Date: Tuesday, November 30, 2010, 1:33 PM
I
couldn't find any specs for a Stiletto 26 but the 27's range from 1100 pounds for the base model to the 27SE at 1550 pounds.? Coming from a mono, you probably won't mind sacrificing the 22kt top speed, but you will find that these boats don't handle extra weight very well.? This includes tacking and regular sailing.
I know I've said similar things before, but imagine your boat with a regular engine (a less than 10hp outboard in your case) and a gas tank that only holds one gallon.? Convert the drive to electric and the one gallon gas tank weighs more than 500 pounds in AGM or FLA batteries.? Cut the weight in half and the tank gets reduced by about 60% due to Peukert's Effect.? So for the weight of a fairly hefty crewman, you get the equivalent of a little more than 6 cups of gas.
If that is OK, great.? I only bring this up so that you can understand the tradeoff.? I suggest that you sail the boat as is,
before you convert it, just to get a feel for a performance multi.
One of the original proponents for ULDB boats, Bill Lee, said it best, "Fast is Fun!" and I have observed that lighter is faster.? Welcome to the dark side....
Fair winds,
Eric
Marina del Rey, CA
|
|
Re: [Electric Boats] Re: Converting an Albin 27
| Ron,? Real engineers think, then if they are lucky, they can put things together...haha ?and if they are really lucky they have the money to make a few things happen.. ?We continue to build, if we don't the world crumbles around us... ?explore and have fun doing it... ?electric is here to stay... ? storage is catching up, but isn't there yet... ?Dave K
|
--- On Tue, 11/30/10, Ron wrote:
From: Ron
Subject: [Electric Boats] Re: Converting an Albin 27
To: electricboats@...
Date: Tuesday, November 30, 2010, 2:07 PM
Thanks Dave,
I would love to be part of a "session" but not being a real engineer,
I tend to clear a room pretty quick :)
I have many ideas, but not being smart enough to prove they would work, I have been smart enough (or not rich enough) to "not" lose money trying to build some of them.
I hope I'm correct in my thinking "we have a solution that is possible, if we can just push aside all the impossible things that keep it invisible to our minds".
Ron
|
Re: [Electric Boats] Re: Stiletto conversion
Eric, ?I do know what you are talking about poundage wise and I plan on sailing myself silly just the way she is before making any significant changes... ?I've got an 8 hp Johnson 2 stroke right now and a 3 gal tank... ? ?if I go electric and I probably will it will be with a LiPo pack and an Etek, I have 4 motors to choose from, 3 brush and 1 brushless. ? I don't run around any more, don't drink or spend time chasing things that I know I don't want so I spend my money on the passions that I have, sailing and electric projects.. ?got to love what you're doing... ? ?This stiletto 26 is a conversion built by one of the engineers wanting to make a week long camping, beach-able cat with sleep aboard capabilities... ?The design never took off ?but the boat is solid and I like it, with a few astatic changes it could
be a great looking boat, so far the performance is good but I haven't really pushed her. ? I am in the process of building a new boom because I picked up an F24 mainsail the other day and I need 12 Ft and only have 10 on the boom... ?should be fun with that roachie monster on board.. ? I also have a 20 meter sailkite that I want to try, have you ever seen one of these on a boat first hand? ? ?I've seen them on Utube, actually on a 24 tri in Hawaii.... ? Dave K ? Thanks for the welcome to the fast side of the tracks.. ?chuckle
|
--- On Tue, 11/30/10, Eric wrote:
From: Eric
Subject: [Electric Boats] Re: Stiletto conversion
To: electricboats@...
Date: Tuesday, November 30, 2010, 1:33 PM
I
couldn't find any specs for a Stiletto 26 but the 27's range from 1100 pounds for the base model to the 27SE at 1550 pounds.? Coming from a mono, you probably won't mind sacrificing the 22kt top speed, but you will find that these boats don't handle extra weight very well.? This includes tacking and regular sailing.
I know I've said similar things before, but imagine your boat with a regular engine (a less than 10hp outboard in your case) and a gas tank that only holds one gallon.? Convert the drive to electric and the one gallon gas tank weighs more than 500 pounds in AGM or FLA batteries.? Cut the weight in half and the tank gets reduced by about 60% due to Peukert's Effect.? So for the weight of a fairly hefty crewman, you get the equivalent of a little more than 6 cups of gas.
If that is OK, great.? I only bring this up so that you can understand the tradeoff.? I suggest that you sail the boat as is,
before you convert it, just to get a feel for a performance multi.
One of the original proponents for ULDB boats, Bill Lee, said it best, "Fast is Fun!" and I have observed that lighter is faster.? Welcome to the dark side....
Fair winds,
Eric
Marina del Rey, CA
|
[Electric Boats] Re: Converting an Albin 27
Thanks Dave,
I would love to be part of a "session" but not being a real engineer, I tend to clear a room pretty quick :)
I have many ideas, but not being smart enough to prove they would work, I have been smart enough (or not rich enough) to "not" lose money trying to build some of them.
I hope I'm correct in my thinking "we have a solution that is possible, if we can just push aside all the impossible things that keep it invisible to our minds".
Ron
toggle quoted message
Show quoted text
--- In electricboats@..., Dave Kellogg <inganear1@...> wrote:
Ron, have you ever gone to a "brain storm session", we used to have them at
Apple all the time and you could throw out any thoughts that came to mind.
This idea isn't so far fetched at all, it just needs room. I may be a little
of a maniac but I have 4 sailboats from 17 to 37 on deck so it gives me a wide
range of test platforms, love it... What does and old retired, tired inganear
do? He works on projects... chuckle Who said we have to stay
conventional?.... out of the box thoughts are accepted, at least by me..
chuckle... if you have a chance take a look at the Redeemed album, needed a
total rebuild, it would have been a reef if anyone else would have got her...
Dave K
PS: if anyone is looking for a perfect platform for a slippery electric
sailboat conversion that is a solid boat a friend of mine has one. James
Baldwin has an Alberg 30 on a trailer in southeast Georgia that would be
perfect, all the rigging and sails, just needs the interior and what ever
auxiliary power you want to put in it.. I believe he has it on his web site
www.atomvoyages.com
________________________________
From: Ron <rlgravel@...>
To: electricboats@...
Sent: Mon, November 29, 2010 2:35:15 PM
Subject: [Electric Boats] Re: Converting an Albin 27
Dave, Sorry if I posted out of context, it was a flash of mechanics and no
thought of restrictions of the present hull.
If it has any value at all, it might require a complete new boat design to make
it practical.
Ron
--- In electricboats@..., Dave Kellogg <inganear1@> wrote:
Question Ron, how much room do you have under your waterline? I only had
enough room for a 14 inch prop and a 1 inch cross section nozzle, and I had to
make some real changes in my rudder... Room is the problem.. Dave K
PS... I have some pictures in the album section.
________________________________
From: Ron <rlgravel@>
To: electricboats@...
Sent: Mon, November 29, 2010 1:58:40 PM
Subject: [Electric Boats] Re: Converting an Albin 27
Dave,
You made a great point about weight, a large mass in motion will be less
sensitive to extracting a regen value.
I'll throw out an idea, but will not try to explain in too much detail, as I
can
never say things just right.
A two function design using the nozzle you mention, a small high speed power
prop inside the nozzle and the nozzle turns as a large regen unit, having
several blades on the outside diameter that can be feathered for least
resistance when the power prop is in use, then feathered for maximum regen when
being powered by wind or current movment.
So basiclly a two prop system. Massive torque and high speed power seem to
always be on opposite ends of where they are needed.
Ron
------------------------------------
Yahoo! Groups Links
|
I couldn't find any specs for a Stiletto 26 but the 27's range from 1100 pounds for the base model to the 27SE at 1550 pounds. Coming from a mono, you probably won't mind sacrificing the 22kt top speed, but you will find that these boats don't handle extra weight very well. This includes tacking and regular sailing.
I know I've said similar things before, but imagine your boat with a regular engine (a less than 10hp outboard in your case) and a gas tank that only holds one gallon. Convert the drive to electric and the one gallon gas tank weighs more than 500 pounds in AGM or FLA batteries. Cut the weight in half and the tank gets reduced by about 60% due to Peukert's Effect. So for the weight of a fairly hefty crewman, you get the equivalent of a little more than 6 cups of gas.
If that is OK, great. I only bring this up so that you can understand the tradeoff. I suggest that you sail the boat as is, before you convert it, just to get a feel for a performance multi.
One of the original proponents for ULDB boats, Bill Lee, said it best, "Fast is Fun!" and I have observed that lighter is faster. Welcome to the dark side....
Fair winds,
Eric
Marina del Rey, CA
toggle quoted message
Show quoted text
--- In electricboats@..., Dave Kellogg <inganear1@...> wrote:
Eric,
I understand were your coming from on the electric drive for your Tri and not
wanting the weight of the batteries. Something that the multi hullers should
also consider is the fact that the multi's are much, much slipperier than the
sleekest mono. The battery bank could be much smaller and if balanced in the
hull or hulls on a Cat the weight would be noticed less in performance. I just
bought a 26 Sitletto and will probably go electric with it, maybe a little
different from the normal electric hung off the back or through a hull. I'll
run the electric drive in a center pod under the deck and a long shaft on a
pivot to extract totally while sailing. I can split the bank and install them
closer to the center of the hulls for better weight distribution. I've been a
mono sailor all my life and I'm kinda excited about having these 2 Cat's to play
with... Dave K
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Re: [Electric Boats] Re: more regen conversation
Eric, I understand were your coming from on the electric drive for your Tri and not wanting the weight of the batteries. ? Something that the multi hullers should also consider is the fact that the multi's are much, much slipperier than the sleekest mono. ?The battery bank could be much smaller and if balanced in the hull or hulls on a Cat the weight would be noticed less in performance. ? I just bought a 26 Sitletto and will probably go electric with it, maybe a little different from the normal electric hung off the back or through a hull.??I'll run the electric drive in a center pod under the deck and a long shaft on a pivot to extract totally while sailing. ? I can split the bank and install them closer to the center of the hulls for better
weight distribution. ? I've been a mono sailor all my life and I'm kinda excited about having these 2 Cat's to play with... ?Dave K
From: Eric
To: electricboats@...
Sent: Mon, November 29, 2010 6:52:33 PM
Subject: [Electric Boats] Re: more regen conversation
Larry, As the most visible "regen naysayer" here, the link that you provided completely supports my previous premise.? According to the Whoosh site "... And since we average 5-6 kts, that's over 100 amp/hrs/day ¨C for us quite possibly 150 amp/hrs/day ¨C that is available for running the radar at night, making water with offshore water quality, feeding the SSB radio, and keeping the iPod charged..."? So what does this mean?? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24 hours or 50-75W at 5-6kts.? They do say that the harvested water power is sufficicient for house loads, a statement that I wholeheartedly agree with. My statement is (and always has been) that regen at speeds around 5kts is not a viable source of charging for a traction battery bank.? The speed is important because most displacement auxilliary sailboats between 27-32 feet (optimal for a 5kW electric drive) have a hard time
hitting sustained runs above 6 kts.? For this size boat, average sailing speeds of about 5.5kts is more realistic.? So let's say that you use 4kWh of energy out of your 10kWh battery bank, that's about 10-12nm at 4kts in most of our boats.? How far would you have to sail using the system described by Whoosh to bring your batteries back to full charge, assuming that you are using no electrical power in the mean time?? Generating 75W at 6kts, that's 12.5Wh/nm.? So 4kWh will take 320nm of sailing at 6kts and will take over 53 hours.? Slow down to 5kts under sail and the recharge distance is up to 400nm and will take 80 hours.? If you have a 12V house load of only 2A, the recharge times and distances double. Ignoring house loads, the ratio of drive distance (at 4kts) to regen distance (at 5kts) is about 1 to 40.? Motor one mile at 4kts (15 minutes) and you need to sail 40 miles at 5kts (8 hours) to get
the charge back.? If you use a radio, autopilot or lights, the ratio gets worse. So regen works, but is not as effective at recharging your traction batteries as some drive vendors would like you to believe. Fair winds, Eric Marina del Rey --- In electricboats@..., "Larry Doyle" wrote: > > Here's to those NaySayers that say regen doesn't work.? Here's some boats that are doing it using towed gens as well as the free wheeling the prop/dc motor in regen mode. > > > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go
to: ? ? <*> Your email settings: ? ? Individual Email | Traditional <*> To change settings online go to: ? ? ? ? (Yahoo! ID required) <*> To change settings via email: ? ? electricboats-digest@... ? ? electricboats-fullfeatured@...<*> To unsubscribe from this group, send an email to: ? ?
electricboats-unsubscribe@...<*> Your use of Yahoo! Groups is subject to: ? ?
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Re: [Electric Boats] AC vs DC Motor
I have 36' steel sailboat so unless batteries get better and cheeper I will be using a 5 to 10 kw generator.
From: Orest Iwaszko
To: electricboats@...
Sent: Mon, November 29, 2010 12:07:51 PM
Subject: Re: [Electric Boats] AC vs DC Motor
?
i too am interested in using AC ? ? ?you must have a generator I presume ... wondering how many kw? ? ? ?Wil be following this thread ?. ? ?I heard ?that 2kw produces around 1 hp' ? ?
On 2010-11-24, at 9:22 PM, akenai wrote:
?
I have been looking at the AC-13 or AC-15 AC Motors they are large enough to use on my 36' steel hull, But I have not found much info that I could understand as to compair them to DC motors other than the few DC drives that are in the higher hp range and then the cost gets to extreme. carries the set as well as
These look like a nice package and the price dosent seam to bad.
Anyone familer with these? Arby talked about AC awhile back.
Aaron
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Re: [Electric Boats] Re: Converting an Alberg 30
Check out Triton called "Atom" he made some stands so that you can stand it up on the beach at low tide. Really cool. Triton has the same draft as the Alberg 30.
Dan
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--- On Mon, 11/29/10, Eric wrote:
From: Eric
Subject: [Electric Boats] Re: Converting an Alberg 30
To: electricboats@...
Date: Monday, November 29, 2010, 6:57 PM
?
According to the Alberg 30 site, the draft is 4'3", not exactly shoal draft but a ways from 6ft. But any full keel boat isn't going to respond well to laying on the beach, even my Bermuda 30 at 3'8".
I'm interested to hear what type of sailboat that you are considering if you're planning on beaching it. I know that there are a couple of designs from areas with outrageous tidal variances, boats with twin keels that remain standing up when the water disappears.
I guess that a centerboarder would do OK when beached, but you should have some braces on lines that can help keep the boat upright as the tide receeds. The other option is a multihull, but the weight of an electric drive with batteries will definately influence your sailing performance.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@..., Bill Spires wrote:
>
> Depending on how far the class will let you go and what type of conversion you
> install you may make the boat ineligible for one design fleet racing or you may
> just make it non-competitive. The Alberg 30 class seems to have fairly loose
> rules about engine mods so you may be ok. For me the 6 ft draft was a deal
> killer. I am building an electric boat i can beach.
>
>
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Sally Reuther