|
Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.  Facts and figures for SV/Retreat Time Catamaran LOA 44 ' Water line 40' Beam 20 Draft 3.5 Propeller 19 " Diameter 3 blade Pitch 19 degree Displacement 26,000 lbs. Battery bank per hull consists of 12 group 31 AGM Duracell 100AH Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts, Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts. Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ?  Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.? Thanks John
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Is it a sail cat or just engine powered, John ??
I'm a bit confused, why you need 2x18KW for a cat
On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577@...> wrote:
Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits. Facts and figures for SV/Retreat Time Catamaran LOA 44 ' Water line 40' Beam 20 Draft 3.5 Propeller 19 " Diameter 3 blade Pitch 19 degree Displacement 26,000 lbs. Battery bank per hull consists of 12 group 31 AGM Duracell 100AH Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts, Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts. Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ? Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.? Thanks John
|
One reason you might choose this particular kit is to get the water-cooled motor.? I think if you want to be able to motor continuously at speed you really need more robust cooling than the air cooled units will give you.? Also at more modest speeds you will not be pushing the system so hard.?? But I don't think there is enough battery reserve here.?
If I am reading the description correctly you will have a 72V 200AH AGM bank in each hull?? That will be 100AH usable capacity (50% depth of discharge).? I am sure there are some Catamaran dynamics that make the comparison problematic but for my 13,000 lb monohull 100AH of usable capacity would get me about 10 miles at 5 knots.? That would not be good enough for my purposes.? Is a 26,000 lb cat like two 13,000 monohulls?? Probably not and with the higher hull speed of 40'LWL maybe you would do better?? Still seems like too short a range for practical purposes.?
Regardless of how you divide up the battery banks you still have a total capacity (with 24 batteries) of 28,800 Whrs.? But with AGM you have 50% depth of discharge so it's 14,400Whrs usable which is marginal I think.?
I would consider running at 48V and configuring the batteries for 4S3P on each hull for two 48V 300AH banks.?? Still the same Whrs total - that's the good thing about looking at it in Whrs.?? The motor would be 12kW at that voltage and 2500RPM max.?? I thought the ME1616 is 96 V max anyway?? So 144V banks won't be an option??
Then again, with a CAT it might be nice to be able to run the port side from the starboard battery and higher voltage would be better for that.? But I am not so keen on the high voltage.??? But it can be done.? You still have the same total Whrs and that's what the range is based on.?
Prop speed depends on the size of the props.? I have an 18" prop with a 3:1 reduction for 800 RPM max.?? This has been an excellent match for me.?? Bigger and slower prop will be better.? You have 19" so I would target a prop speed of 600 to 900 RPM.??? This may be another reason to go 48V because max motor RPM will be 2500.? At 72 it's 3600 RPM??? That means 4:1 to get the prop rotation where you want it.? That may be more difficult to come up with regarding reduction gear parts.?? You can do 3:1 pretty simply though I am not sure what those limits might be with the Thunderstruck reduction units.??
But it also depends on pitch.? You say 19deg pitch?? That is typically expressed in inches of pitch.? How many inches will the boat move forward for one rev of the prop. ? Can you translate that 19deg to inches of pitch?? If that's what it was, 19 inches, then it's a pretty big pitch which also means slow RPM.??? My 18" prop is set to a theoretical pitch of 13.5".?? It's a feathering prop so the behavior is not exactly the same.?? But if it was 19" of pitch I would need an even slower RPM.? Like 600.?
Lots of variables to work with...
Dan Pfeiffer
toggle quoted message
Show quoted text
On 2022-01-30 4:24 pm, Carsten via groups.io wrote:
?
Is it a sail cat or just engine powered, John ??
?
I'm a bit confused, why you need 2x18KW for a cat
?
?
On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577@...> wrote:
?
?
Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.  Facts and figures for SV/Retreat Time Catamaran LOA 44 ' Water line 40' Beam 20 Draft 3.5 Propeller 19 " Diameter 3 blade Pitch 19 degree Displacement 26,000 lbs. Battery bank per hull consists of 12 group 31 AGM Duracell 100AH Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts, Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts. Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ? Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.? Thanks John
|
Hi, John
Be careful of doing so. You may end up being fried instantly ! You'll get toasted. Ask a VERY good marine engineer electrician to do the switch installation job for you, buddy. The connections must be sea water safe.
About the props, consult a "prop pro" too, otherwise you'll end up with something that you can spend years of changing, always not efficient.
Unless you have your big own 3D printer to make different prop blades again and again - save the time and let the pro's calculate it for you. 2x 18 KW is a lot for a cat.
But, realize :
How much do you actually need these engines ? It's a sailboat ! That is your main engine, right ?
Learn to sail your vessel well, then you won't need those two 18 KW engines, right ? Something smaller could do it.
Thanks Dan, for your last comment. Very useful (like always from you).
Carsten
On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577@...> wrote:
Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits. ![]() Facts and figures for SV/Retreat Time Catamaran LOA 44 ' Water line 40' Beam 20 Draft 3.5 Propeller 19 " Diameter 3 blade Pitch 19 degree Displacement 26,000 lbs. Battery bank per hull consists of 12 group 31 AGM Duracell 100AH Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts, Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts. Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ? ![]() Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.? Thanks John
|
Hi, Dan
The props are probably the real key here... And, actually, the use of the cat. If you have a cat, then consider retractable engines in the middle. Stupid to have a big fast cat, with fixed props hanging there, behind...
Many cats are not real sailboats, just double hull motoring boats. No mast. I don't know about John's cat yet.
I just think, that 2x 18 KW electric is a way overkill for a cat sailboat. It is supposed to go fast, when sail. Not by battery powered engines. The sails are much more powerful, and can last across an ocean for years.
My 8000 lb old mono can sail without an engine, of course, but it helps, with even a small 10 HP outboard, when coming in waters without much sailing possibility...
Cheers, Carsten
On Monday, 31 January 2022, 03:06:09 CET, Dan Pfeiffer <dan@...> wrote:
One reason you might choose this particular kit is to get the water-cooled motor.? I think if you want to be able to motor continuously at speed you really need more robust cooling than the air cooled units will give you.? Also at more modest speeds you will not be pushing the system so hard.?? But I don't think there is enough battery reserve here.?
If I am reading the description correctly you will have a 72V 200AH AGM bank in each hull?? That will be 100AH usable capacity (50% depth of discharge).? I am sure there are some Catamaran dynamics that make the comparison problematic but for my 13,000 lb monohull 100AH of usable capacity would get me about 10 miles at 5 knots.? That would not be good enough for my purposes.? Is a 26,000 lb cat like two 13,000 monohulls?? Probably not and with the higher hull speed of 40'LWL maybe you would do better?? Still seems like too short a range for practical purposes.?
Regardless of how you divide up the battery banks you still have a total capacity (with 24 batteries) of 28,800 Whrs.? But with AGM you have 50% depth of discharge so it's 14,400Whrs usable which is marginal I think.?
I would consider running at 48V and configuring the batteries for 4S3P on each hull for two 48V 300AH banks.?? Still the same Whrs total - that's the good thing about looking at it in Whrs.?? The motor would be 12kW at that voltage and 2500RPM max.?? I thought the ME1616 is 96 V max anyway?? So 144V banks won't be an option??
Then again, with a CAT it might be nice to be able to run the port side from the starboard battery and higher voltage would be better for that.? But I am not so keen on the high voltage.??? But it can be done.? You still have the same total Whrs and that's what the range is based on.?
Prop speed depends on the size of the props.? I have an 18" prop with a 3:1 reduction for 800 RPM max.?? This has been an excellent match for me.?? Bigger and slower prop will be better.? You have 19" so I would target a prop speed of 600 to 900 RPM.??? This may be another reason to go 48V because max motor RPM will be 2500.? At 72 it's 3600 RPM??? That means 4:1 to get the prop rotation where you want it.? That may be more difficult to come up with regarding reduction gear parts.?? You can do 3:1 pretty simply though I am not sure what those limits might be with the Thunderstruck reduction units.??
But it also depends on pitch.? You say 19deg pitch?? That is typically expressed in inches of pitch.? How many inches will the boat move forward for one rev of the prop. ? Can you translate that 19deg to inches of pitch?? If that's what it was, 19 inches, then it's a pretty big pitch which also means slow RPM.??? My 18" prop is set to a theoretical pitch of 13.5".?? It's a feathering prop so the behavior is not exactly the same.?? But if it was 19" of pitch I would need an even slower RPM.? Like 600.?
Lots of variables to work with...
Dan Pfeiffer
On 2022-01-30 4:24 pm, Carsten via groups.io wrote:
?
Is it a sail cat or just engine powered, John ??
?
I'm a bit confused, why you need 2x18KW for a cat
?
?
On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577@...> wrote:
?
?
Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.
Facts and figures for SV/Retreat Time Catamaran
LOA 44 '
Water line 40'
Beam 20
Draft 3.5
Propeller 19 " Diameter 3 blade
Pitch 19 degree
Displacement 26,000 lbs.
Battery bank per hull consists of 12 group 31 AGM Duracell 100AH
Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts,
Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts.
Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ?
Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.?
Thanks John
|
I did a lot of number crunching and estimating or the performance of my electric drive before I built it.? That was mostly based on performance reports from other similar boats and some other prediction formulas and spreadsheets.? Once I was up and running I was getting significantly better performance than predicted.? I was exceeding predictions by 30 to 50%.?? I predicted 5 knots would take 3600 Watts.? It takes more like 2400 (flat calm). ? I attribute most of this to the excellent match of my propeller.? I am lucky to have a large diameter feathering prop (18") where I can change the pitch (not underway).? If you are simply swapping the electric for the diesel with the same fixed prop you are probably giving up some significant performance.? I would fit the largest prop that will fit and set up the reduction gear to get it spinning at the slowest practical speed.?? That's harder with a fixed prop as you are committed to the pitch so it's harder to experiment.? But there are big gains in performance to be made by getting a good match with the prop.?
Having said all that, I would certainly give up motor performance for sailing performance.?? I have a feathering prop so I get a good bit of both.? But sailing comes first.?? It also depends on your use.? I am mostly day sailing these days so 25 miles of electric range at 5 knots is fine (better than expected).? I plan to get back to occasional voyaging and for that I feel the need for sustained motoring capacity to make passages up rivers and through canals from time to time.? And for now I think the most practical way to achieve that is with an inboard diesel genset.? I think I could get over 55 miles range at 3 knots but loafing along like that amidst real ship traffic is not appealing.?
Dan Pfeiffer
toggle quoted message
Show quoted text
On 2022-01-30 9:41 pm, Carsten via groups.io wrote:
?
Hi, Dan
?
The props are probably the real key here...
And, actually, the use of the cat.
If you have a cat, then consider retractable engines in the middle.
Stupid to have a big fast cat, with fixed props hanging there, behind...
?
Many cats are not real sailboats, just double hull motoring boats. No mast.
I don't know about John's cat yet.
?
I just think, that 2x 18 KW electric is a way overkill for a cat sailboat.
It is supposed to go fast, when sail. Not by battery powered engines.
The sails are much more powerful, and can last across an ocean for years.
?
My 8000 lb old mono can sail without an engine, of course, but it helps, with even a small 10 HP outboard, when coming in waters without much sailing possibility...
?
Cheers,
Carsten
?
On Monday, 31 January 2022, 03:06:09 CET, Dan Pfeiffer <dan@...> wrote:
?
?
One reason you might choose this particular kit is to get the water-cooled motor.? I think if you want to be able to motor continuously at speed you really need more robust cooling than the air cooled units will give you.? Also at more modest speeds you will not be pushing the system so hard.?? But I don't think there is enough battery reserve here.?
If I am reading the description correctly you will have a 72V 200AH AGM bank in each hull?? That will be 100AH usable capacity (50% depth of discharge).? I am sure there are some Catamaran dynamics that make the comparison problematic but for my 13,000 lb monohull 100AH of usable capacity would get me about 10 miles at 5 knots.? That would not be good enough for my purposes.? Is a 26,000 lb cat like two 13,000 monohulls?? Probably not and with the higher hull speed of 40'LWL maybe you would do better?? Still seems like too short a range for practical purposes.?
Regardless of how you divide up the battery banks you still have a total capacity (with 24 batteries) of 28,800 Whrs.? But with AGM you have 50% depth of discharge so it's 14,400Whrs usable which is marginal I think.?
I would consider running at 48V and configuring the batteries for 4S3P on each hull for two 48V 300AH banks.?? Still the same Whrs total - that's the good thing about looking at it in Whrs.?? The motor would be 12kW at that voltage and 2500RPM max.?? I thought the ME1616 is 96 V max anyway?? So 144V banks won't be an option??
Then again, with a CAT it might be nice to be able to run the port side from the starboard battery and higher voltage would be better for that.? But I am not so keen on the high voltage.??? But it can be done.? You still have the same total Whrs and that's what the range is based on.?
Prop speed depends on the size of the props.? I have an 18" prop with a 3:1 reduction for 800 RPM max.?? This has been an excellent match for me.?? Bigger and slower prop will be better.? You have 19" so I would target a prop speed of 600 to 900 RPM.??? This may be another reason to go 48V because max motor RPM will be 2500.? At 72 it's 3600 RPM??? That means 4:1 to get the prop rotation where you want it.? That may be more difficult to come up with regarding reduction gear parts.?? You can do 3:1 pretty simply though I am not sure what those limits might be with the Thunderstruck reduction units.??
But it also depends on pitch.? You say 19deg pitch?? That is typically expressed in inches of pitch.? How many inches will the boat move forward for one rev of the prop. ? Can you translate that 19deg to inches of pitch?? If that's what it was, 19 inches, then it's a pretty big pitch which also means slow RPM.??? My 18" prop is set to a theoretical pitch of 13.5".?? It's a feathering prop so the behavior is not exactly the same.?? But if it was 19" of pitch I would need an even slower RPM.? Like 600.?
Lots of variables to work with...
Dan Pfeiffer
On 2022-01-30 4:24 pm, Carsten via groups.io wrote:
?
Is it a sail cat or just engine powered, John ??
?
I'm a bit confused, why you need 2x18KW for a cat
?
?
On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577@...> wrote:
?
?
Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits. ![]() Facts and figures for SV/Retreat Time Catamaran LOA 44 ' Water line 40' Beam 20 Draft 3.5 Propeller 19 " Diameter 3 blade Pitch 19 degree Displacement 26,000 lbs. Battery bank per hull consists of 12 group 31 AGM Duracell 100AH Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts, Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts. Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ? ![]() Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.? Thanks John
?
|
Thank you, Dan
I'll revert in a day.
I have the same issue, with channelling to the berth.
I do not use engine when out on the sea, but winds can get so bad, so it is more comfortable to do motoring, for a while, especially when singlehanded. Then the power should be there, for sure.
My present old Volvo is useless for that.
We still need to hear what John's actual use of his cat are.
On Monday, 31 January 2022, 09:48:25 CET, Dan Pfeiffer <dan@...> wrote:
I did a lot of number crunching and estimating or the performance of my electric drive before I built it.? That was mostly based on performance reports from other similar boats and some other prediction formulas and spreadsheets.? Once I was up and running I was getting significantly better performance than predicted.? I was exceeding predictions by 30 to 50%.?? I predicted 5 knots would take 3600 Watts.? It takes more like 2400 (flat calm). ? I attribute most of this to the excellent match of my propeller.? I am lucky to have a large diameter feathering prop (18") where I can change the pitch (not underway).? If you are simply swapping the electric for the diesel with the same fixed prop you are probably giving up some significant performance.? I would fit the largest prop that will fit and set up the reduction gear to get it spinning at the slowest practical speed.?? That's harder with a fixed prop as you are committed to the pitch so it's harder to experiment.? But there are big gains in performance to be made by getting a good match with the prop.?
Having said all that, I would certainly give up motor performance for sailing performance.?? I have a feathering prop so I get a good bit of both.? But sailing comes first.?? It also depends on your use.? I am mostly day sailing these days so 25 miles of electric range at 5 knots is fine (better than expected).? I plan to get back to occasional voyaging and for that I feel the need for sustained motoring capacity to make passages up rivers and through canals from time to time.? And for now I think the most practical way to achieve that is with an inboard diesel genset.? I think I could get over 55 miles range at 3 knots but loafing along like that amidst real ship traffic is not appealing.?
Dan Pfeiffer
On 2022-01-30 9:41 pm, Carsten via groups.io wrote:
?
Hi, Dan
?
The props are probably the real key here...
And, actually, the use of the cat.
If you have a cat, then consider retractable engines in the middle.
Stupid to have a big fast cat, with fixed props hanging there, behind...
?
Many cats are not real sailboats, just double hull motoring boats. No mast.
I don't know about John's cat yet.
?
I just think, that 2x 18 KW electric is a way overkill for a cat sailboat.
It is supposed to go fast, when sail. Not by battery powered engines.
The sails are much more powerful, and can last across an ocean for years.
?
My 8000 lb old mono can sail without an engine, of course, but it helps, with even a small 10 HP outboard, when coming in waters without much sailing possibility...
?
Cheers,
Carsten
?
On Monday, 31 January 2022, 03:06:09 CET, Dan Pfeiffer <dan@...> wrote:
?
?
One reason you might choose this particular kit is to get the water-cooled motor.? I think if you want to be able to motor continuously at speed you really need more robust cooling than the air cooled units will give you.? Also at more modest speeds you will not be pushing the system so hard.?? But I don't think there is enough battery reserve here.?
If I am reading the description correctly you will have a 72V 200AH AGM bank in each hull?? That will be 100AH usable capacity (50% depth of discharge).? I am sure there are some Catamaran dynamics that make the comparison problematic but for my 13,000 lb monohull 100AH of usable capacity would get me about 10 miles at 5 knots.? That would not be good enough for my purposes.? Is a 26,000 lb cat like two 13,000 monohulls?? Probably not and with the higher hull speed of 40'LWL maybe you would do better?? Still seems like too short a range for practical purposes.?
Regardless of how you divide up the battery banks you still have a total capacity (with 24 batteries) of 28,800 Whrs.? But with AGM you have 50% depth of discharge so it's 14,400Whrs usable which is marginal I think.?
I would consider running at 48V and configuring the batteries for 4S3P on each hull for two 48V 300AH banks.?? Still the same Whrs total - that's the good thing about looking at it in Whrs.?? The motor would be 12kW at that voltage and 2500RPM max.?? I thought the ME1616 is 96 V max anyway?? So 144V banks won't be an option??
Then again, with a CAT it might be nice to be able to run the port side from the starboard battery and higher voltage would be better for that.? But I am not so keen on the high voltage.??? But it can be done.? You still have the same total Whrs and that's what the range is based on.?
Prop speed depends on the size of the props.? I have an 18" prop with a 3:1 reduction for 800 RPM max.?? This has been an excellent match for me.?? Bigger and slower prop will be better.? You have 19" so I would target a prop speed of 600 to 900 RPM.??? This may be another reason to go 48V because max motor RPM will be 2500.? At 72 it's 3600 RPM??? That means 4:1 to get the prop rotation where you want it.? That may be more difficult to come up with regarding reduction gear parts.?? You can do 3:1 pretty simply though I am not sure what those limits might be with the Thunderstruck reduction units.??
But it also depends on pitch.? You say 19deg pitch?? That is typically expressed in inches of pitch.? How many inches will the boat move forward for one rev of the prop. ? Can you translate that 19deg to inches of pitch?? If that's what it was, 19 inches, then it's a pretty big pitch which also means slow RPM.??? My 18" prop is set to a theoretical pitch of 13.5".?? It's a feathering prop so the behavior is not exactly the same.?? But if it was 19" of pitch I would need an even slower RPM.? Like 600.?
Lots of variables to work with...
Dan Pfeiffer
On 2022-01-30 4:24 pm, Carsten via groups.io wrote:
?
Is it a sail cat or just engine powered, John ??
?
I'm a bit confused, why you need 2x18KW for a cat
?
?
On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577@...> wrote:
?
?
Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.
Facts and figures for SV/Retreat Time Catamaran
LOA 44 '
Water line 40'
Beam 20
Draft 3.5
Propeller 19 " Diameter 3 blade
Pitch 19 degree
Displacement 26,000 lbs.
Battery bank per hull consists of 12 group 31 AGM Duracell 100AH
Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts,
Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts.
Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ?
Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.?
Thanks John
?
|
S/V Retreat Time is a sail cat, intended purpose is coastal cruising, 1st season Bahamas second season Maine, third season sea of Cortez.
No particular reason for the 18KW systems, they are robust for sure, we have been caught in some 25-30 knot winds and apposing tide and our motors got hot and I do not want to be in that situation again. It was one of those times I should have waited it out, however it blew for three more days. The main reasoning for 18 kw is to electro sail, using the big props to regen while underway, and have plenty of power when needed.
I'm digging the reduced voltage and the increased amp hours approach, and I will discuss this with Brenard for the final tune, I would like to thank all who offered up their advice and knowledge and time to consider us.
John Winterrowd 702 343 1492 4.2.1. Email Disclaimer NOTICE: The information contained in this electronic transmission is intended only for the use of the individual or entity named above. ANY DISTRIBUTION OR COPYING OF THIS MESSAGE IS PROHIBITED, except by the intended recipient. Attempts to intercept this message are in violation of 18 U.S.C. 2511(1) of the Electronic Communications Privacy Act, which subjects the interceptor to fines, imprisonment and/or civil damages. If you are not the intended recipient, please delete it and notify me.
On Sunday, January 30, 2022, 09:06:10 PM EST, Dan Pfeiffer <dan@...> wrote:
One reason you might choose this particular kit is to get the water-cooled motor.? I think if you want to be able to motor continuously at speed you really need more robust cooling than the air cooled units will give you.? Also at more modest speeds you will not be pushing the system so hard.?? But I don't think there is enough battery reserve here.?
If I am reading the description correctly you will have a 72V 200AH AGM bank in each hull?? That will be 100AH usable capacity (50% depth of discharge).? I am sure there are some Catamaran dynamics that make the comparison problematic but for my 13,000 lb monohull 100AH of usable capacity would get me about 10 miles at 5 knots.? That would not be good enough for my purposes.? Is a 26,000 lb cat like two 13,000 monohulls?? Probably not and with the higher hull speed of 40'LWL maybe you would do better?? Still seems like too short a range for practical purposes.?
Regardless of how you divide up the battery banks you still have a total capacity (with 24 batteries) of 28,800 Whrs.? But with AGM you have 50% depth of discharge so it's 14,400Whrs usable which is marginal I think.?
I would consider running at 48V and configuring the batteries for 4S3P on each hull for two 48V 300AH banks.?? Still the same Whrs total - that's the good thing about looking at it in Whrs.?? The motor would be 12kW at that voltage and 2500RPM max.?? I thought the ME1616 is 96 V max anyway?? So 144V banks won't be an option??
Then again, with a CAT it might be nice to be able to run the port side from the starboard battery and higher voltage would be better for that.? But I am not so keen on the high voltage.??? But it can be done.? You still have the same total Whrs and that's what the range is based on.?
Prop speed depends on the size of the props.? I have an 18" prop with a 3:1 reduction for 800 RPM max.?? This has been an excellent match for me.?? Bigger and slower prop will be better.? You have 19" so I would target a prop speed of 600 to 900 RPM.??? This may be another reason to go 48V because max motor RPM will be 2500.? At 72 it's 3600 RPM??? That means 4:1 to get the prop rotation where you want it.? That may be more difficult to come up with regarding reduction gear parts.?? You can do 3:1 pretty simply though I am not sure what those limits might be with the Thunderstruck reduction units.??
But it also depends on pitch.? You say 19deg pitch?? That is typically expressed in inches of pitch.? How many inches will the boat move forward for one rev of the prop. ? Can you translate that 19deg to inches of pitch?? If that's what it was, 19 inches, then it's a pretty big pitch which also means slow RPM.??? My 18" prop is set to a theoretical pitch of 13.5".?? It's a feathering prop so the behavior is not exactly the same.?? But if it was 19" of pitch I would need an even slower RPM.? Like 600.?
Lots of variables to work with...
Dan Pfeiffer
On 2022-01-30 4:24 pm, Carsten via groups.io wrote: ? Is it a sail cat or just engine powered, John ?? ? I'm a bit confused, why you need 2x18KW for a cat ? ? On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577@...> wrote: ? ? Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.
Facts and figures for SV/Retreat Time Catamaran
LOA 44 '
Water line 40'
Beam 20
Draft 3.5
Propeller 19 " Diameter 3 blade
Pitch 19 degree
Displacement 26,000 lbs.
Battery bank per hull consists of 12 group 31 AGM Duracell 100AH
Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts,
Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts.
Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ?
Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.?
Thanks John
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I have the same size cat 39-1/2’ x 17’. She has a pair of Motenergy water-cooled 48v PMAC motors. Top speed is 6.3 knots. I have 18”x14” 3-blade Hang Shen props and a 3:1 reduction. Max motor RPM is 2,400RPM. I chose the reduction and props after much head scratching using both empirical and tank test data. I am comfortable that I picked right - motor spins up to 2,400 - no more - no less.?
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Split the batteries would be my advice - keep a way to parallel the two packs.?
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John, Looking back and wondered how things went for you?
We have a 35,000lb, 12.5:1 L:B power cat, 50' x 17' which runs 23" x 18" props.? At 750rpm (1500rpm using 2:1 reduction) we get about 7kn using both diesels, at something like 30hp each on a 2.8 prop curve. We have some estimates for electric, where our acceptable sweet spot is more at 5-5.5kn. We are looking at twin ME1616, preferably running at 8kW ea or 75%. Thunderstruck 3:1 reduction seems a decent guesstimated match, though noone seems to "know", and finding prop people who know electric is nigh impossible locally.?
Rob
On Sun, 30 Jan 2022, 12:26 am john winterrowd via , <sailorboy55577= [email protected]> wrote: Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.
Facts and figures for SV/Retreat Time Catamaran
LOA 44 '
Water line 40'
Beam 20
Draft 3.5
Propeller 19 " Diameter 3 blade
Pitch 19 degree
Displacement 26,000 lbs.
Battery bank per hull consists of 12 group 31 AGM Duracell 100AH
Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts,
Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts.
Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. ?
Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week.?
Thanks John
_._,_._,_
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I have a 34’, 13500 lb keel/centerboard cat/ketch with a Thunderstruck 12kw watercooled kit. Prop is 17” x 13” fixed 2 blade. I am using the “large” Thunderstruck 2.5-1 gear reduction which is chain rather than belt. Initially the boat was over-propped and the current draw overwhelmed the C rating of the bank. I bought 10’ of SS #50 roller chain, 3 different size motor sprockets and a chain breaker all for ?$200. Changing the reduction ratio takes less than 1 hour and I do not have to haul the boat. Things are working much better now at 3.33-1. Interesting how good regen worked when it was over-propped.?
i am using a 3kw aircooled quiet generator on propane to reduce my range anxiety. I have it mounted in a cockpit locker with 2 x 3” 12 volt blowers evacuating the locker and a water jacketed extension exhausting out the transom. Temps in the locker are 110 degrees max. Generator can keep up with the load at 4 knots.
?
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Have you got any performance data??
My setup is very similar.? 12500lb, 33ft (28.3 LWL) monohull.? I also have the Thunderstruck 12kW liquid cooled (ME1616).? I have? 3:1 reduction that I fabricated myself and a three bladed 18" feathering prop that I can adjust the pitch on.? My performance has exceeded the predictions by 10-15% and I think that is largely due to being able to more closely match the prop to the motor and reduction gear.??
This season I increased the prop pitch by 1 setting.? The effective change in pitch is approximately from 13.5" to 15" so from 18x13.5 to 18x15.? I only have one set of data and it seems like I have increased the performance significanly with this change.? Like 30% less power for same speed.?? It seems too big an improvement to be believed so I will need to collect more data and change the pitch back to repeat the data collection at the previous setting.?? And at the lower pitch setting max throttle would peak at 250 amps or so.? Now I saw it spike up to 310amps which is above C rating (280 amps) so I need to check on that least I cause some damage.?? But that was the value from the Sevcon through the bluetooth to my tablet and it does NOT agree with the Victron BMV712 which I trust for being correct for power draw on with it's shunt.?
So, interesting but more data to collect.? I built a new cooling system controller and I need to install that before proceeding to high power testing.?
Dan Pfeiffer
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On 2023-06-02 8:34 am, kurtphone@... wrote:
I have a 34’, 13500 lb keel/centerboard cat/ketch with a Thunderstruck 12kw watercooled kit. Prop is 17” x 13” fixed 2 blade. I am using the “large” Thunderstruck 2.5-1 gear reduction which is chain rather than belt. Initially the boat was over-propped and the current draw overwhelmed the C rating of the bank. I bought 10’ of SS #50 roller chain, 3 different size motor sprockets and a chain breaker all for ?$200. Changing the reduction ratio takes less than 1 hour and I do not have to haul the boat. Things are working much better now at 3.33-1. Interesting how good regen worked when it was over-propped.?
i am using a 3kw aircooled quiet generator on propane to reduce my range anxiety. I have it mounted in a cockpit locker with 2 x 3” 12 volt blowers evacuating the locker and a water jacketed extension exhausting out the transom. Temps in the locker are 110 degrees max. Generator can keep up with the load at 4 knots.
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Regarding the discrepancy in current readings between the Sevcon and Victron, it could be due to the Sevcon reporting motor current while the Victron reports battery current.? The controller, being a switching power converter effectively can deliver a very high average current at an average voltage (at the motor) of less than the pack.? Meanwhile, I imagine the Victron reports battery voltage and current.? The product of each I,V pair should come out close to the other (minus controller losses). ? -MT ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Dan Pfeiffer
Sent: Friday, June 2, 2023 11:29 AM
To: [email protected]
Subject: Re: [electricboats] Re Power for SV/Retreat Time Catamaran? Have you got any performance data??
My setup is very similar.? 12500lb, 33ft (28.3 LWL) monohull.? I also have the Thunderstruck 12kW liquid cooled (ME1616).? I have? 3:1 reduction that I fabricated myself and a three bladed 18" feathering prop that I can adjust the pitch on.? My performance has exceeded the predictions by 10-15% and I think that is largely due to being able to more closely match the prop to the motor and reduction gear.??
This season I increased the prop pitch by 1 setting.? The effective change in pitch is approximately from 13.5" to 15" so from 18x13.5 to 18x15.? I only have one set of data and it seems like I have increased the performance significanly with this change.? Like 30% less power for same speed.?? It seems too big an improvement to be believed so I will need to collect more data and change the pitch back to repeat the data collection at the previous setting.?? And at the lower pitch setting max throttle would peak at 250 amps or so.? Now I saw it spike up to 310amps which is above C rating (280 amps) so I need to check on that least I cause some damage.?? But that was the value from the Sevcon through the bluetooth to my tablet and it does NOT agree with the Victron BMV712 which I trust for being correct for power draw on with it's shunt.?
So, interesting but more data to collect.? I built a new cooling system controller and I need to install that before proceeding to high power testing.?
Dan Pfeiffer
On 2023-06-02 8:34 am, kurtphone@... wrote: ? I have a 34’, 13500 lb keel/centerboard cat/ketch with a Thunderstruck 12kw watercooled kit. Prop is 17” x 13” fixed 2 blade. I am using the “large” Thunderstruck 2.5-1 gear reduction which is chain rather than belt. Initially the boat was over-propped and the current draw overwhelmed the C rating of the bank. I bought 10’ of SS #50 roller chain, 3 different size motor sprockets and a chain breaker all for ?$200. Changing the reduction ratio takes less than 1 hour and I do not have to haul the boat. Things are working much better now at 3.33-1. Interesting how good regen worked when it was over-propped.?
i am using a 3kw aircooled quiet generator on propane to reduce my range anxiety. I have it mounted in a cockpit locker with 2 x 3” 12 volt blowers evacuating the locker and a water jacketed extension exhausting out the transom. Temps in the locker are 110 degrees max. Generator can keep up with the load at 4 knots.
?
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Agreed but Sevcon was reading about 20% higher than Victron.? And I think Sevcon and Victron voltages did match but I will have to check that.? There are some calibration factors in the canbus translator.? I have not explored it in detail.? Dan Pfeiffer
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On 2023-06-02 4:20 pm, Myles Twete wrote:
Regarding the discrepancy in current readings between the Sevcon and Victron, it could be due to the Sevcon reporting motor current while the Victron reports battery current.? The controller, being a switching power converter effectively can deliver a very high average current at an average voltage (at the motor) of less than the pack.? Meanwhile, I imagine the Victron reports battery voltage and current.? The product of each I,V pair should come out close to the other (minus controller losses).
?
-MT
?
?
Have you got any performance data??
My setup is very similar.? 12500lb, 33ft (28.3 LWL) monohull.? I also have the Thunderstruck 12kW liquid cooled (ME1616).? I have? 3:1 reduction that I fabricated myself and a three bladed 18" feathering prop that I can adjust the pitch on.? My performance has exceeded the predictions by 10-15% and I think that is largely due to being able to more closely match the prop to the motor and reduction gear.??
This season I increased the prop pitch by 1 setting.? The effective change in pitch is approximately from 13.5" to 15" so from 18x13.5 to 18x15.? I only have one set of data and it seems like I have increased the performance significanly with this change.? Like 30% less power for same speed.?? It seems too big an improvement to be believed so I will need to collect more data and change the pitch back to repeat the data collection at the previous setting.?? And at the lower pitch setting max throttle would peak at 250 amps or so.? Now I saw it spike up to 310amps which is above C rating (280 amps) so I need to check on that least I cause some damage.?? But that was the value from the Sevcon through the bluetooth to my tablet and it does NOT agree with the Victron BMV712 which I trust for being correct for power draw on with it's shunt.?
So, interesting but more data to collect.? I built a new cooling system controller and I need to install that before proceeding to high power testing.?
Dan Pfeiffer
On 2023-06-02 8:34 am, kurtphone@... wrote:
?
I have a 34', 13500 lb keel/centerboard cat/ketch with a Thunderstruck 12kw watercooled kit. Prop is 17" x 13" fixed 2 blade. I am using the "large" Thunderstruck 2.5-1 gear reduction which is chain rather than belt. Initially the boat was over-propped and the current draw overwhelmed the C rating of the bank. I bought 10' of SS #50 roller chain, 3 different size motor sprockets and a chain breaker all for ?$200. Changing the reduction ratio takes less than 1 hour and I do not have to haul the boat. Things are working much better now at 3.33-1. Interesting how good regen worked when it was over-propped.?
i am using a 3kw aircooled quiet generator on propane to reduce my range anxiety. I have it mounted in a cockpit locker with 2 x 3" 12 volt blowers evacuating the locker and a water jacketed extension exhausting out the transom. Temps in the locker are 110 degrees max. Generator can keep up with the load at 4 knots.
?
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Sure, if the voltages reported were the same a 20% higher current on the Sevcon would be odd. Definitely check this because when you went to a steeper pitch the motor current went up for a given motor voltage. Motor current could easily be 20% or even 50% or higher than the battery current---again, because the controller is effectively trading voltage for current thru switching. -MT ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Dan Pfeiffer
Sent: Friday, June 2, 2023 2:50 PM
To: [email protected]
Subject: Re: [electricboats] Re Power for SV/Retreat Time Catamaran? Agreed but Sevcon was reading about 20% higher than Victron.? And I think Sevcon and Victron voltages did match but I will have to check that.? There are some calibration factors in the canbus translator.? I have not explored it in detail.?
Dan Pfeiffer
On 2023-06-02 4:20 pm, Myles Twete wrote: Regarding the discrepancy in current readings between the Sevcon and Victron, it could be due to the Sevcon reporting motor current while the Victron reports battery current.? The controller, being a switching power converter effectively can deliver a very high average current at an average voltage (at the motor) of less than the pack.? Meanwhile, I imagine the Victron reports battery voltage and current.? The product of each I,V pair should come out close to the other (minus controller losses). ? -MT ? ? Have you got any performance data??
My setup is very similar.? 12500lb, 33ft (28.3 LWL) monohull.? I also have the Thunderstruck 12kW liquid cooled (ME1616).? I have? 3:1 reduction that I fabricated myself and a three bladed 18" feathering prop that I can adjust the pitch on.? My performance has exceeded the predictions by 10-15% and I think that is largely due to being able to more closely match the prop to the motor and reduction gear.??
This season I increased the prop pitch by 1 setting.? The effective change in pitch is approximately from 13.5" to 15" so from 18x13.5 to 18x15.? I only have one set of data and it seems like I have increased the performance significanly with this change.? Like 30% less power for same speed.?? It seems too big an improvement to be believed so I will need to collect more data and change the pitch back to repeat the data collection at the previous setting.?? And at the lower pitch setting max throttle would peak at 250 amps or so.? Now I saw it spike up to 310amps which is above C rating (280 amps) so I need to check on that least I cause some damage.?? But that was the value from the Sevcon through the bluetooth to my tablet and it does NOT agree with the Victron BMV712 which I trust for being correct for power draw on with it's shunt.?
So, interesting but more data to collect.? I built a new cooling system controller and I need to install that before proceeding to high power testing.?
Dan Pfeiffer
? On 2023-06-02 8:34 am, kurtphone@... wrote: ? I have a 34', 13500 lb keel/centerboard cat/ketch with a Thunderstruck 12kw watercooled kit. Prop is 17" x 13" fixed 2 blade. I am using the "large" Thunderstruck 2.5-1 gear reduction which is chain rather than belt. Initially the boat was over-propped and the current draw overwhelmed the C rating of the bank. I bought 10' of SS #50 roller chain, 3 different size motor sprockets and a chain breaker all for ?$200. Changing the reduction ratio takes less than 1 hour and I do not have to haul the boat. Things are working much better now at 3.33-1. Interesting how good regen worked when it was over-propped.?
i am using a 3kw aircooled quiet generator on propane to reduce my range anxiety. I have it mounted in a cockpit locker with 2 x 3" 12 volt blowers evacuating the locker and a water jacketed extension exhausting out the transom. Temps in the locker are 110 degrees max. Generator can keep up with the load at 4 knots.
?
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I believe the current (amp draw) that you see from the sevcon is motor amps not battery amps
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Reuben Trane