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Glenn,
Good reasoning on developing your budget, but I find your orignal budget a little aggressive, you will propbably go over that number by the time you get a running conversion with basic instrumentation. You can leave some stuff off, but you'll probably end up spending the money eventually. To do the project as you describe, I would brace yourself for about $5k US. Who knows, you could even come in under that...
Looking at your design parameter, you said that your basic "stretch" requirement is 20Mn @ 4kts. I find that somewhat challenging but still reasonable. Let's do a little math.. :)
Because we don't know anything else about your system yet, we'll have to go with some broad estimates. But I will go out on a limb and state that these "guesses" will be closer than you might think.
The first assumption is that your boat will take about 1500W (2hp) to power at 4kts. You might do better, you could do worse, but this is close enough for estimating. At 4kts, you'll need 5 hours of capacity. I never estimate a battery pack at more than 80% depth of discharge (DoD), even if the battery chemistry can take it. If you think about it, when was the last time that you ran your car to 100% DoD of the gas tank? I think that we all fill up before we run completely out of fuel and typically treat our boats the same.
Speaking of battery chemistry, different types of batteries act differently in storing energy, delivering energy and their lifespan measured in charging cycles. How far you regularly discharge your batteries can affect their lifespan, but this thread is not the place for that discussion, I don't want to get sidetracked...
So for your battery types, I will use 65% DoD for flooded batteries (FLA) and 80% DoD for AGM. If you want to use different DoD, let me know and I can recalculate the numbers.
So we're aiming for 5 hrs at 1500W. Here we go....
FLA batteries like T-105s or T-125s have a Peukerts exponent of 1.25 and using a 65% DoD, you need 14kWh to give you the required 9100Wh usable to run for 5 hours. That's 290Ah of FLA batteries at 48V. US Battery makes the US305EXC 290Ah 6V battery that weighs 102 pounds; you would need 8 batteries for a combined weight of 816 pounds. These batteries seem to cost about $200 a piece or $1600 for your boat
AGM batteries have a Peukerts exponent around 1.15 and using a 80% DoD, you need 11kWh to give you the required 8800Wh usable to run for 5 hours. That's 230Ah of AGM batteries at 48V. Trojan makes the 8D-AGM 230Ah 12V battery that weighs 167 pounds; you would need 4 batteries for a combined weight of 668 pounds. These batteries appear to cost around $650 online or $2600 for your boat
Just for fun, let's look at LiFePO4 batteries, they have a Peukerts exponent around 1.05 and using a 80% DoD, you need 10kWh to give you the required 8000Wh usable to run for 5 hours. That's 200Ah of LiFePO4 batteries at 48V. Thundersky makes the TS-LYP-200AHA 200Ah 3.2V battery that weighs 16.1 pounds; you would need 16 cells for a combined weight of 260 pounds. These batteries cost $260 or $4160 for your boat. Lithium batteries should have extra protection; a battery management system (BMS) will cost approximately $500 for these batteries, pushing the cost to around $4700.
Whew, that's a lot of info, but I suggest that you mull it over for a while and see how it feels. Another answer is to change your requirements, a 15 mile range @ 4kts is obviously cheaper and lighter and so is 20Nm @ 3kts.
But I like your original request, my 30' ketch conversion with LiFePO4 batteries is spec'd to run 16Nm @ 4 kts. I should be able to verify that performance within a month or two and I'll post my results here.
Fair winds,
Eric
Marina del Rey, CA
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--- In electricboats@..., "Glenn Dennis" <vega1184@...> wrote:
Eric and all
I set the budget based on what it would cost me to repower with a new/old stock diesel (Volvo MD2001 9 Hp, 1 Cyl). I currently have a non-working inboard gas with feathering prop (Albin Combi drive) that is too small to work with anything else. I use a 9.9 outboard mounted on the transom, it works for the most part but if there is over 2 or 3 ft swell the prop tends to come out of the water and you can't charge the house batteries. Most of my motoring is just out and in to the Club, less than 10 min @ 3 or 4 Kts, each way most days. Top speed is not a real concern 5 or 5.5 kts would be more than enough, but would I have to have longer range for when you have to get back. I would like 20 Nm @ 4kts. I have had the boat two years now and mostly just day sail with a couple of weekend trips every now and then, but I want to do longer trips. Also I sail solo often.
With either option I will need Prop, shaft, coupling, exhaust, etc. Because of design the largest prop I could fit would be 13 inches, maybe 14 if I could get it back far enough, I was considering a 13 X 13 pitch. As for space the Vega is blessed/cursed with 23" wide X 48" long X 16" high void behind the current engine occupied by only an exhaust pipe. Also it's easy to make wider, I could fit 4 X 8d batteries no problem. Weight however would be another issue at 4 x 66 kg she may have a bow up attitude. I could try to keep them as for forward as possible may making a step cover for one. 6 volt GC batteries would be easier to distribute.
"As long as you approach this project with your eyes open to what it really means, then you shouldn't be disappointed."
That's why I'm here, trying to learn as much as possible before I comitt to the project. Oh and it would be nice to have a quiet "green" boat.
Glenn
|
Eric
Thanks for the input, IMO the battery is key here.
The actual power required to push the boat and the reserve capacity was what I was unsure of. It's good to get advice from some one who has experience in the field rather than just going it alone. Truthfully I had been more interested in the mechanical part of the system and did not put much effort in calculating the battery requirements. I was a little optimistic on range but I could start with smaller pack and go larger later. L/A or AGM will certainly add a lot of weight, maybe a smaller lithium pack, say 40 or 50 Ah and generator (Hybrid) would be the way to go. Several things to consider and of course cost; the boat although in very good shape is 39 years old.
Glenn
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--- In electricboats@..., "Eric" <ewdysar@...> wrote:
Glenn,
Good reasoning on developing your budget, but I find your orignal budget a little aggressive, you will propbably go over that number by the time you get a running conversion with basic instrumentation. You can leave some stuff off, but you'll probably end up spending the money eventually. To do the project as you describe, I would brace yourself for about $5k US. Who knows, you could even come in under that...
Looking at your design parameter, you said that your basic "stretch" requirement is 20Mn @ 4kts. I find that somewhat challenging but still reasonable. Let's do a little math.. :)
Because we don't know anything else about your system yet, we'll have to go with some broad estimates. But I will go out on a limb and state that these "guesses" will be closer than you might think.
The first assumption is that your boat will take about 1500W (2hp) to power at 4kts. You might do better, you could do worse, but this is close enough for estimating. At 4kts, you'll need 5 hours of capacity. I never estimate a battery pack at more than 80% depth of discharge (DoD), even if the battery chemistry can take it. If you think about it, when was the last time that you ran your car to 100% DoD of the gas tank? I think that we all fill up before we run completely out of fuel and typically treat our boats the same.
Speaking of battery chemistry, different types of batteries act differently in storing energy, delivering energy and their lifespan measured in charging cycles. How far you regularly discharge your batteries can affect their lifespan, but this thread is not the place for that discussion, I don't want to get sidetracked...
So for your battery types, I will use 65% DoD for flooded batteries (FLA) and 80% DoD for AGM. If you want to use different DoD, let me know and I can recalculate the numbers.
So we're aiming for 5 hrs at 1500W. Here we go....
FLA batteries like T-105s or T-125s have a Peukerts exponent of 1.25 and using a 65% DoD, you need 14kWh to give you the required 9100Wh usable to run for 5 hours. That's 290Ah of FLA batteries at 48V. US Battery makes the US305EXC 290Ah 6V battery that weighs 102 pounds; you would need 8 batteries for a combined weight of 816 pounds. These batteries seem to cost about $200 a piece or $1600 for your boat
AGM batteries have a Peukerts exponent around 1.15 and using a 80% DoD, you need 11kWh to give you the required 8800Wh usable to run for 5 hours. That's 230Ah of AGM batteries at 48V. Trojan makes the 8D-AGM 230Ah 12V battery that weighs 167 pounds; you would need 4 batteries for a combined weight of 668 pounds. These batteries appear to cost around $650 online or $2600 for your boat
Just for fun, let's look at LiFePO4 batteries, they have a Peukerts exponent around 1.05 and using a 80% DoD, you need 10kWh to give you the required 8000Wh usable to run for 5 hours. That's 200Ah of LiFePO4 batteries at 48V. Thundersky makes the TS-LYP-200AHA 200Ah 3.2V battery that weighs 16.1 pounds; you would need 16 cells for a combined weight of 260 pounds. These batteries cost $260 or $4160 for your boat. Lithium batteries should have extra protection; a battery management system (BMS) will cost approximately $500 for these batteries, pushing the cost to around $4700.
Whew, that's a lot of info, but I suggest that you mull it over for a while and see how it feels. Another answer is to change your requirements, a 15 mile range @ 4kts is obviously cheaper and lighter and so is 20Nm @ 3kts.
But I like your original request, my 30' ketch conversion with LiFePO4 batteries is spec'd to run 16Nm @ 4 kts. I should be able to verify that performance within a month or two and I'll post my results here.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Eric and all
I set the budget based on what it would cost me to repower with a new/old stock diesel (Volvo MD2001 9 Hp, 1 Cyl). I currently have a non-working inboard gas with feathering prop (Albin Combi drive) that is too small to work with anything else. I use a 9.9 outboard mounted on the transom, it works for the most part but if there is over 2 or 3 ft swell the prop tends to come out of the water and you can't charge the house batteries. Most of my motoring is just out and in to the Club, less than 10 min @ 3 or 4 Kts, each way most days. Top speed is not a real concern 5 or 5.5 kts would be more than enough, but would I have to have longer range for when you have to get back. I would like 20 Nm @ 4kts. I have had the boat two years now and mostly just day sail with a couple of weekend trips every now and then, but I want to do longer trips. Also I sail solo often.
With either option I will need Prop, shaft, coupling, exhaust, etc. Because of design the largest prop I could fit would be 13 inches, maybe 14 if I could get it back far enough, I was considering a 13 X 13 pitch. As for space the Vega is blessed/cursed with 23" wide X 48" long X 16" high void behind the current engine occupied by only an exhaust pipe. Also it's easy to make wider, I could fit 4 X 8d batteries no problem. Weight however would be another issue at 4 x 66 kg she may have a bow up attitude. I could try to keep them as for forward as possible may making a step cover for one. 6 volt GC batteries would be easier to distribute.
"As long as you approach this project with your eyes open to what it really means, then you shouldn't be disappointed."
That's why I'm here, trying to learn as much as possible before I comitt to the project. Oh and it would be nice to have a quiet "green" boat.
Glenn
|
Glenn,
I wouldn't go smaller than a 90 or 100Ah Li battery bank, small banks have bigger issues with Peukert's Effect, they lose more power under high load rates. You could also consider 4 group 31 AGM (105Ah) to begin with, they would weigh about 280 pounds, but you should get about an 8Nm range at 4Kts to 80% DoD. Then after you win the lottery, you can upgrade to the latest Li batteries. :)
If you're thinking generator, Mike has been successful with his Honda 2000 and a charger, I think that he can put about 15A into his system when the generator is running, that is about half of your 4kt load, so your batteires should last twice as long at that speed. There are some chargers available that can deliver more than 20A at 48V running on a Honda or Yamaha 2000 generator. The generator should be on deck while running. But the good part is that you don't need to set it up until you think that tyou need the range. If it's truly a day sail, you can leave the generator ashore.
It sounds like your getting your head wrapped around this project. Let us know if you need more info as you do more research.
Fair winds,
Eric
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--- In electricboats@..., "Glenn Dennis" <vega1184@...> wrote:
Eric
Thanks for the input, IMO the battery is key here.
The actual power required to push the boat and the reserve capacity was what I was unsure of. It's good to get advice from some one who has experience in the field rather than just going it alone. Truthfully I had been more interested in the mechanical part of the system and did not put much effort in calculating the battery requirements. I was a little optimistic on range but I could start with smaller pack and go larger later. L/A or AGM will certainly add a lot of weight, maybe a smaller lithium pack, say 40 or 50 Ah and generator (Hybrid) would be the way to go. Several things to consider and of course cost; the boat although in very good shape is 39 years old.
Glenn
|
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps. At that point I was using a small 2 blade prop that gave me 3 knts at that current draw. I now have a fixed 3 blade that gives me 4 knts at 20 amps.
During that trip I used only one of the two 48 volt 100 amp hr banks that I have. I do not know how deep I discharged that bank because I didn't have a monitor at that point. It was probably deeper than you should discharge but I did have power at that point.
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
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Show quoted text
--- In electricboats@..., "Eric" <ewdysar@...> wrote:
Glenn,
I wouldn't go smaller than a 90 or 100Ah Li battery bank, small banks have bigger issues with Peukert's Effect, they lose more power under high load rates. You could also consider 4 group 31 AGM (105Ah) to begin with, they would weigh about 280 pounds, but you should get about an 8Nm range at 4Kts to 80% DoD. Then after you win the lottery, you can upgrade to the latest Li batteries. :)
If you're thinking generator, Mike has been successful with his Honda 2000 and a charger, I think that he can put about 15A into his system when the generator is running, that is about half of your 4kt load, so your batteires should last twice as long at that speed. There are some chargers available that can deliver more than 20A at 48V running on a Honda or Yamaha 2000 generator. The generator should be on deck while running. But the good part is that you don't need to set it up until you think that tyou need the range. If it's truly a day sail, you can leave the generator ashore.
It sounds like your getting your head wrapped around this project. Let us know if you need more info as you do more research.
Fair winds,
Eric
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Eric
Thanks for the input, IMO the battery is key here.
The actual power required to push the boat and the reserve capacity was what I was unsure of. It's good to get advice from some one who has experience in the field rather than just going it alone. Truthfully I had been more interested in the mechanical part of the system and did not put much effort in calculating the battery requirements. I was a little optimistic on range but I could start with smaller pack and go larger later. L/A or AGM will certainly add a lot of weight, maybe a smaller lithium pack, say 40 or 50 Ah and generator (Hybrid) would be the way to go. Several things to consider and of course cost; the boat although in very good shape is 39 years old.
Glenn
|
Mark
What motor and controller do you have? Did you get it as a kit or build it your self? What gear ratio and prop are you running? Sorry for all the questions but I am trying to figure this out.
Glenn
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--- In electricboats@..., "acsarfkram" <acsarfkram@...> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps. At that point I was using a small 2 blade prop that gave me 3 knts at that current draw. I now have a fixed 3 blade that gives me 4 knts at 20 amps.
During that trip I used only one of the two 48 volt 100 amp hr banks that I have. I do not know how deep I discharged that bank because I didn't have a monitor at that point. It was probably deeper than you should discharge but I did have power at that point.
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Eric" <ewdysar@> wrote:
|
Hi Glenn,
I bought a factory built unit from SolidNav, the Explorer model. It has a Mars motor with a Sevcon controller. I think the gear ratio is 2 to 1 maybe a bit more than 2, you should be able to find that info on their web site.
The prop I'm using is a fixed 3 blade 12x10. I would like to try a 12x11 or 12 some day as I think I would get a higher top speed. Currently I have a top speed in calm conditions of 5.7 knts. My concern is loosing the 4 knts at 20 amps, I would not sacrifice that for a higher top speed. But 4knts at 16 amps....:-)
You can see some photos in the photo section here under "Lotus Flower".
I've been running my system non stop since May of 2008 and am very pleased. Good luck with your research and possible repower.
Mark
Santa Cruz
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--- In electricboats@..., "Glenn Dennis" <vega1184@...> wrote:
Mark
What motor and controller do you have? Did you get it as a kit or build it your self? What gear ratio and prop are you running? Sorry for all the questions but I am trying to figure this out.
Glenn
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps. At that point I was using a small 2 blade prop that gave me 3 knts at that current draw. I now have a fixed 3 blade that gives me 4 knts at 20 amps.
During that trip I used only one of the two 48 volt 100 amp hr banks that I have. I do not know how deep I discharged that bank because I didn't have a monitor at that point. It was probably deeper than you should discharge but I did have power at that point.
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Eric" <ewdysar@> wrote:
|
Eric and anyone else
Still lots to think about. Now I would like to determine prop pitch and gearing. Some of the electric conversion web sites say that because of the torque produced by a electric motor you should go to a large pitched prop. The largest prop I could fit is a 13 inch dia prop, obviously the more pitch the more torque required to turn it at a given RPM and the more boat speed. Aprox boat speed can estimated by pitch x prop RPM, but how would you determine the amperage draw to achieve that RPM. Of course gearing would come into the picture but that's easy to deal with. I guess my question boils down to, is it more efficient to run a electric motor at medium or high RPM? i.e. If I want to motor at 4 knots would I gear the motor to turn at 2400 RPM (max) or at 2000 RPM. Since I would be using 4 knots as an common speed I would pitch the prop to be most efficient at that speed. Yes
this is starting to wander but both issues are connected.
And to really highlight my ignorance is the speed of AC motors regulated by voltage like DC or by amperage or both.
Glenn
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--- In electricboats@..., "Eric" <ewdysar@...> wrote:
Glenn,
I wouldn't go smaller than a 90 or 100Ah Li battery bank, small banks have bigger issues with Peukert's Effect, they lose more power under high load rates. You could also consider 4 group 31 AGM (105Ah) to begin with, they would weigh about 280 pounds, but you should get about an 8Nm range at 4Kts to 80% DoD. Then after you win the lottery, you can upgrade to the latest Li batteries. :)
If you're thinking generator, Mike has been successful with his Honda 2000 and a charger, I think that he can put about 15A into his system when the generator is running, that is about half of your 4kt load, so your batteires should last twice as long at that speed. There are some chargers available that can deliver more than 20A at 48V running on a Honda or Yamaha 2000 generator. The generator should be on deck while running. But the good part is that you don't need to set it up until you think that tyou need the range. If it's truly a day sail, you can leave the generator ashore.
It sounds like your getting your head wrapped around this project. Let us know if you need more info as you do more research.
Fair winds,
Eric
|
Mark
Very nice install. The solidNav is a nice unit. I liked the disc brake, was it your idea? Getting the pitch right is a concern of mine, I can get a 13 x 13 prop but I don't want to over prop it. All the prop calulators point to a 13 x 9 or 10, but the're based on a IC motor.
Glenn
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--- In electricboats@..., "acsarfkram" <acsarfkram@...> wrote:
Hi Glenn,
I bought a factory built unit from SolidNav, the Explorer model. It has a Mars motor with a Sevcon controller. I think the gear ratio is 2 to 1 maybe a bit more than 2, you should be able to find that info on their web site.
The prop I'm using is a fixed 3 blade 12x10. I would like to try a 12x11 or 12 some day as I think I would get a higher top speed. Currently I have a top speed in calm conditions of 5.7 knts. My concern is loosing the 4 knts at 20 amps, I would not sacrifice that for a higher top speed. But 4knts at 16 amps....:-)
You can see some photos in the photo section here under "Lotus Flower".
I've been running my system non stop since May of 2008 and am very pleased. Good luck with your research and possible repower.
Mark
Santa Cruz
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Mark
What motor and controller do you have? Did you get it as a kit or build it your self? What gear ratio and prop are you running? Sorry for all the questions but I am trying to figure this out.
Glenn
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps. At that point I was using a small 2 blade prop that gave me 3 knts at that current draw. I now have a fixed 3 blade that gives me 4 knts at 20 amps.
During that trip I used only one of the two 48 volt 100 amp hr banks that I have. I do not know how deep I discharged that bank because I didn't have a monitor at that point. It was probably deeper than you should discharge but I did have power at that point.
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Eric" <ewdysar@> wrote:
|
Yes the brake (Avid mountain bike brake) set-up was my design. An issue with the early Sevcons for marine use was that they would not allow you to shift instantly from full forward to reverse. The controller wanted to see a stopped shaft. The brake let me stop the shaft at will and shift. Also I like to lock the shaft while sailing so I don't hear the motor turning. Of course if I want regen I do not lock the shaft.
Mark
Santa Cruz
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--- In electricboats@..., "Glenn Dennis" <vega1184@...> wrote:
Mark
Very nice install. The solidNav is a nice unit. I liked the disc brake, was it your idea? Getting the pitch right is a concern of mine, I can get a 13 x 13 prop but I don't want to over prop it. All the prop calulators point to a 13 x 9 or 10, but the're based on a IC motor.
Glenn
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
I bought a factory built unit from SolidNav, the Explorer model. It has a Mars motor with a Sevcon controller. I think the gear ratio is 2 to 1 maybe a bit more than 2, you should be able to find that info on their web site.
The prop I'm using is a fixed 3 blade 12x10. I would like to try a 12x11 or 12 some day as I think I would get a higher top speed. Currently I have a top speed in calm conditions of 5.7 knts. My concern is loosing the 4 knts at 20 amps, I would not sacrifice that for a higher top speed. But 4knts at 16 amps....:-)
You can see some photos in the photo section here under "Lotus Flower".
I've been running my system non stop since May of 2008 and am very pleased. Good luck with your research and possible repower.
Mark
Santa Cruz
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Mark
What motor and controller do you have? Did you get it as a kit or build it your self? What gear ratio and prop are you running? Sorry for all the questions but I am trying to figure this out.
Glenn
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps. At that point I was using a small 2 blade prop that gave me 3 knts at that current draw. I now have a fixed 3 blade that gives me 4 knts at 20 amps.
During that trip I used only one of the two 48 volt 100 amp hr banks that I have. I do not know how deep I discharged that bank because I didn't have a monitor at that point. It was probably deeper than you should discharge but I did have power at that point.
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Eric" <ewdysar@> wrote:
|
Mark,
You've posted these results before and the impressive part is that you pulled 140Ah (20A x 7hrs) out of 100Ah batteries and had some left over. While I am not discounting your accomplishment, I would not recommend that other people count on getting the same results from the same setup. If you share the specific brand and model of battery that you are using, then more people here can take advantage of these under-rated batteries.
Fair winds,
Eric
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--- In electricboats@..., "acsarfkram" <acsarfkram@...> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps....
During that trip I used only one of the two 48 volt 100 amp hr banks that I have....
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Eric
Thanks for the input, IMO the battery is key here.
The actual power required to push the boat and the reserve capacity was what I was unsure of. It's good to get advice from some one who has experience in the field rather than just going it alone. Truthfully I had been more interested in the mechanical part of the system and did not put much effort in calculating the battery requirements. I was a little optimistic on range but I could start with smaller pack and go larger later. L/A or AGM will certainly add a lot of weight, maybe a smaller lithium pack, say 40 or 50 Ah and generator (Hybrid) would be the way to go. Several things to consider and of course cost; the boat although in very good shape is 39 years old.
Glenn
|
Hi Eric,
I've posted this before; 4 West Marine (East Penn) group 27's and 4 universal UB121100 group 30's.
It was dead calm when we motored for this long. We had the main up the entire time and tried varying amounts of headsail (we had a lot of time to play around :-). When the headsail was unfurled we would keep weight to leaward which would keep the sail somewhat full. I think you do get "lift" from the sail in this configuration like an aircraft but That's just my "feeling" I have no proof. My PakTrakr is down below so I do not constantly see my current draw and I was using the GPS at the helm and keeping the speed at 3 knots. Every time I checked the amp usage it was between 18 and 21 amps.
I totally understand your skepticism, the numbers don't work but I think there may be some sort of "Black Magic" in pushing a sailboat hull through a thick fluid and thin airfoils through a thin fluid.
Boy that ought to go over well with this group :-)
I look forward to you actually using your system and documenting your performance.
Mark
Santa Cruz
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--- In electricboats@..., "Eric" <ewdysar@...> wrote:
Mark,
You've posted these results before and the impressive part is that you pulled 140Ah (20A x 7hrs) out of 100Ah batteries and had some left over. While I am not discounting your accomplishment, I would not recommend that other people count on getting the same results from the same setup. If you share the specific brand and model of battery that you are using, then more people here can take advantage of these under-rated batteries.
Fair winds,
Eric
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps....
During that trip I used only one of the two 48 volt 100 amp hr banks that I have....
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Eric
Thanks for the input, IMO the battery is key here.
The actual power required to push the boat and the reserve capacity was what I was unsure of. It's good to get advice from some one who has experience in the field rather than just going it alone. Truthfully I had been more interested in the mechanical part of the system and did not put much effort in calculating the battery requirements. I was a little optimistic on range but I could start with smaller pack and go larger later. L/A or AGM will certainly add a lot of weight, maybe a smaller lithium pack, say 40 or 50 Ah and generator (Hybrid) would be the way to go. Several things to consider and of course cost; the boat although in very good shape is 39 years old.
Glenn
|
Hi. I am resuming my conversion plans and question if building a system from scratch using as basis a Sevcon Brushless Sailboat Kit - 8.5KW () instaead of the SolidNav unit is worth the hassle. Cost is about half, but you must add the heat sink, gear reduction system and holding rails. Your input is highly appreciated.
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--- In electricboats@..., "acsarfkram" <acsarfkram@...> wrote:
Hi Glenn,
I bought a factory built unit from SolidNav, the Explorer model. It has a Mars motor with a Sevcon controller. I think the gear ratio is 2 to 1 maybe a bit more than 2, you should be able to find that info on their web site.
The prop I'm using is a fixed 3 blade 12x10. I would like to try a 12x11 or 12 some day as I think I would get a higher top speed. Currently I have a top speed in calm conditions of 5.7 knts. My concern is loosing the 4 knts at 20 amps, I would not sacrifice that for a higher top speed. But 4knts at 16 amps....:-)
You can see some photos in the photo section here under "Lotus Flower".
I've been running my system non stop since May of 2008 and am very pleased. Good luck with your research and possible repower.
Mark
Santa Cruz
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Mark
What motor and controller do you have? Did you get it as a kit or build it your self? What gear ratio and prop are you running? Sorry for all the questions but I am trying to figure this out.
Glenn
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps. At that point I was using a small 2 blade prop that gave me 3 knts at that current draw. I now have a fixed 3 blade that gives me 4 knts at 20 amps.
During that trip I used only one of the two 48 volt 100 amp hr banks that I have. I do not know how deep I discharged that bank because I didn't have a monitor at that point. It was probably deeper than you should discharge but I did have power at that point.
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Eric" <ewdysar@> wrote:
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Hi Carlos,
For me buying an engineered unit was worth the money. I'm sure it would have taken quite a while to fabricate a unit. I've done enough projects to know that there will almost always be mistakes made that will cost money and time.
That said I like building stuff and got my tinkering fix figuring out where and how to mount batteries, wiring everything together, experimenting with props...
Here is a link (I have no connection)to a great price on a SolidNav Explorer;
Mark
Santa Cruz
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--- In electricboats@..., "Carlos Silva" <pahuac@...> wrote:
Hi. I am resuming my conversion plans and question if building a system from scratch using as basis a Sevcon Brushless Sailboat Kit - 8.5KW () instaead of the SolidNav unit is worth the hassle. Cost is about half, but you must add the heat sink, gear reduction system and holding rails. Your input is highly appreciated.
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
I bought a factory built unit from SolidNav, the Explorer model. It has a Mars motor with a Sevcon controller. I think the gear ratio is 2 to 1 maybe a bit more than 2, you should be able to find that info on their web site.
The prop I'm using is a fixed 3 blade 12x10. I would like to try a 12x11 or 12 some day as I think I would get a higher top speed. Currently I have a top speed in calm conditions of 5.7 knts. My concern is loosing the 4 knts at 20 amps, I would not sacrifice that for a higher top speed. But 4knts at 16 amps....:-)
You can see some photos in the photo section here under "Lotus Flower".
I've been running my system non stop since May of 2008 and am very pleased. Good luck with your research and possible repower.
Mark
Santa Cruz
--- In electricboats@..., "Glenn Dennis" <vega1184@> wrote:
Mark
What motor and controller do you have? Did you get it as a kit or build it your self? What gear ratio and prop are you running? Sorry for all the questions but I am trying to figure this out.
Glenn
--- In electricboats@..., "acsarfkram" <acsarfkram@> wrote:
Hi Glenn,
With my Ericson 27, (7000lbs before batteries) I have motored for 7 hrs at a draw of 20 amps. At that point I was using a small 2 blade prop that gave me 3 knts at that current draw. I now have a fixed 3 blade that gives me 4 knts at 20 amps.
During that trip I used only one of the two 48 volt 100 amp hr banks that I have. I do not know how deep I discharged that bank because I didn't have a monitor at that point. It was probably deeper than you should discharge but I did have power at that point.
I understand the theory dictates lower run times but I would be interested in what people are getting in real life.
Mark
Santa Cruz
--- In electricboats@..., "Eric" <ewdysar@> wrote:
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