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RussG
02-27-2001, 01:33 PM
Any thoughts on the use of an electric engine on a cruising sailboat of 45-50 feet instead of fossil fuel engines? Any possible models on the market?

Any ideas on the most effective way to charge the batteries (excluding hook ups at a dock) to drive that engine?

RussG
02-27-2001, 01:33 PM
Any thoughts on the use of an electric engine on a cruising sailboat of 45-50 feet instead of fossil fuel engines? Any possible models on the market?

Any ideas on the most effective way to charge the batteries (excluding hook ups at a dock) to drive that engine?

RussG
02-27-2001, 01:33 PM
Any thoughts on the use of an electric engine on a cruising sailboat of 45-50 feet instead of fossil fuel engines? Any possible models on the market?

Any ideas on the most effective way to charge the batteries (excluding hook ups at a dock) to drive that engine?

Ian McColgin
02-27-2001, 02:37 PM
There are perfectly good electric launches for sheltered water day use but nothing that'll puch 20T much of anywhere.

It maybe that fuel cells will gain the strength to weight ratio one needs in the nearish future but, alas, not yet.

Ian McColgin
02-27-2001, 02:37 PM
There are perfectly good electric launches for sheltered water day use but nothing that'll puch 20T much of anywhere.

It maybe that fuel cells will gain the strength to weight ratio one needs in the nearish future but, alas, not yet.

Ian McColgin
02-27-2001, 02:37 PM
There are perfectly good electric launches for sheltered water day use but nothing that'll puch 20T much of anywhere.

It maybe that fuel cells will gain the strength to weight ratio one needs in the nearish future but, alas, not yet.

Frank Wentzel
02-27-2001, 11:40 PM
When I worked in the lead-acid battery industry as a rough rule-of-thumb we considered a golf cart battery able to provide 1 horsepower-hour. Therefore six golf cart batteries will provide 3 horsepower for about 2 hours. That's about 350 to 400 pounds of batteries.

Motors should not be too hard to come by. Golf cart motors, or for higher power fork-lift motors, will do the job.

Battery charging is another kettle of fish. Those six batteries will need about 120 to 140 amp-hours at 42 volts. Nothing short of shore power or an IC engine will do that before doomsday.

There are a dozen ways to rig electric propulsion (and I dearly love the concept) but in the end it comes down to the fact that in the forseeable future electrics are heavy, low power and tied closely to a prime mover. http://media5.hypernet.com/~dick/ubb/frown.gif

Frank Wentzel
02-27-2001, 11:40 PM
When I worked in the lead-acid battery industry as a rough rule-of-thumb we considered a golf cart battery able to provide 1 horsepower-hour. Therefore six golf cart batteries will provide 3 horsepower for about 2 hours. That's about 350 to 400 pounds of batteries.

Motors should not be too hard to come by. Golf cart motors, or for higher power fork-lift motors, will do the job.

Battery charging is another kettle of fish. Those six batteries will need about 120 to 140 amp-hours at 42 volts. Nothing short of shore power or an IC engine will do that before doomsday.

There are a dozen ways to rig electric propulsion (and I dearly love the concept) but in the end it comes down to the fact that in the forseeable future electrics are heavy, low power and tied closely to a prime mover. http://media5.hypernet.com/~dick/ubb/frown.gif

Frank Wentzel
02-27-2001, 11:40 PM
When I worked in the lead-acid battery industry as a rough rule-of-thumb we considered a golf cart battery able to provide 1 horsepower-hour. Therefore six golf cart batteries will provide 3 horsepower for about 2 hours. That's about 350 to 400 pounds of batteries.

Motors should not be too hard to come by. Golf cart motors, or for higher power fork-lift motors, will do the job.

Battery charging is another kettle of fish. Those six batteries will need about 120 to 140 amp-hours at 42 volts. Nothing short of shore power or an IC engine will do that before doomsday.

There are a dozen ways to rig electric propulsion (and I dearly love the concept) but in the end it comes down to the fact that in the forseeable future electrics are heavy, low power and tied closely to a prime mover. http://media5.hypernet.com/~dick/ubb/frown.gif

Hesp
02-28-2001, 07:48 AM
Take a look at:
http://www.yacht-builders.com/Shadow%20drive.htm

Quote:
...that its main use is to push tonnage through the water in an efficient and non-polluting way. With performance figures of 5 - 7 hours cruising at 6 - 7 knots in a 10 metre 9,000kg displacement yacht on one battery charge......

John

Hesp
02-28-2001, 07:48 AM
Take a look at:
http://www.yacht-builders.com/Shadow%20drive.htm

Quote:
...that its main use is to push tonnage through the water in an efficient and non-polluting way. With performance figures of 5 - 7 hours cruising at 6 - 7 knots in a 10 metre 9,000kg displacement yacht on one battery charge......

John

Hesp
02-28-2001, 07:48 AM
Take a look at:
http://www.yacht-builders.com/Shadow%20drive.htm

Quote:
...that its main use is to push tonnage through the water in an efficient and non-polluting way. With performance figures of 5 - 7 hours cruising at 6 - 7 knots in a 10 metre 9,000kg displacement yacht on one battery charge......

John

RussG
02-28-2001, 08:25 AM
Hesp,

That looks very promising. Thanks for the lead.

Anyone have any experience with this product or others like it? Are they dependable in a saltwater environment?

RussG
02-28-2001, 08:25 AM
Hesp,

That looks very promising. Thanks for the lead.

Anyone have any experience with this product or others like it? Are they dependable in a saltwater environment?

RussG
02-28-2001, 08:25 AM
Hesp,

That looks very promising. Thanks for the lead.

Anyone have any experience with this product or others like it? Are they dependable in a saltwater environment?

Scott Rosen
02-28-2001, 08:31 AM
I'm sure there are some good reasons to have an electric engine, but concern for the environment isn't one of them.

On a horsepower versus horsepower basis, it takes much more fossil fuel to build and charge a battery to drive a boat, then to simply burn the fuel on board in an internal combustion engine. It's a matter of simple efficiencies, entropy, etc.

It's the California energy mentality--As long as the energy generation pollutes someone else's backyard, it's okay.

Scott Rosen
02-28-2001, 08:31 AM
I'm sure there are some good reasons to have an electric engine, but concern for the environment isn't one of them.

On a horsepower versus horsepower basis, it takes much more fossil fuel to build and charge a battery to drive a boat, then to simply burn the fuel on board in an internal combustion engine. It's a matter of simple efficiencies, entropy, etc.

It's the California energy mentality--As long as the energy generation pollutes someone else's backyard, it's okay.

Scott Rosen
02-28-2001, 08:31 AM
I'm sure there are some good reasons to have an electric engine, but concern for the environment isn't one of them.

On a horsepower versus horsepower basis, it takes much more fossil fuel to build and charge a battery to drive a boat, then to simply burn the fuel on board in an internal combustion engine. It's a matter of simple efficiencies, entropy, etc.

It's the California energy mentality--As long as the energy generation pollutes someone else's backyard, it's okay.

htom
02-28-2001, 10:59 AM
These guys might actually have a "better idea". (These are the folk designing and making the "Shadow Drive"; it's the same idea that was used in the little Martian explorer vehicle that we watched for a week.)


http://solomontechnologies.com/

frequently asked questions: http://solomontechnologies.com/faq.htm

list of installations: http://solomontechnologies.com/installation.htm

Most of these folk seem to be claiming to be able to move 10,000 pounds at 5-6 knots for 5-6 hours or more. It does seem to be more efficient with 144vDC battery packaging, moreso than I'd expect from simple I^2R losses.

Still, carrying 12 12volt batteries is going to keep it out of the 18' aluminum fishing boats for a while, as well as not allowing their 40 kt noise runs to their favorite spots.

But if I remember correctly, the Caledonia Yawl calls for 300 pounds of ballast, and a 25 pound 12v battery isn't anywhere near impossible, just expensive.

htom
02-28-2001, 10:59 AM
These guys might actually have a "better idea". (These are the folk designing and making the "Shadow Drive"; it's the same idea that was used in the little Martian explorer vehicle that we watched for a week.)


http://solomontechnologies.com/

frequently asked questions: http://solomontechnologies.com/faq.htm

list of installations: http://solomontechnologies.com/installation.htm

Most of these folk seem to be claiming to be able to move 10,000 pounds at 5-6 knots for 5-6 hours or more. It does seem to be more efficient with 144vDC battery packaging, moreso than I'd expect from simple I^2R losses.

Still, carrying 12 12volt batteries is going to keep it out of the 18' aluminum fishing boats for a while, as well as not allowing their 40 kt noise runs to their favorite spots.

But if I remember correctly, the Caledonia Yawl calls for 300 pounds of ballast, and a 25 pound 12v battery isn't anywhere near impossible, just expensive.

htom
02-28-2001, 10:59 AM
These guys might actually have a "better idea". (These are the folk designing and making the "Shadow Drive"; it's the same idea that was used in the little Martian explorer vehicle that we watched for a week.)


http://solomontechnologies.com/

frequently asked questions: http://solomontechnologies.com/faq.htm

list of installations: http://solomontechnologies.com/installation.htm

Most of these folk seem to be claiming to be able to move 10,000 pounds at 5-6 knots for 5-6 hours or more. It does seem to be more efficient with 144vDC battery packaging, moreso than I'd expect from simple I^2R losses.

Still, carrying 12 12volt batteries is going to keep it out of the 18' aluminum fishing boats for a while, as well as not allowing their 40 kt noise runs to their favorite spots.

But if I remember correctly, the Caledonia Yawl calls for 300 pounds of ballast, and a 25 pound 12v battery isn't anywhere near impossible, just expensive.

Frank Wentzel
02-28-2001, 11:21 AM
I just read the article on the Shadow power system. Regardless of the transmission used with your motor you still have the problem that the generation of 1 horsepower requires 750 watts. I don't know how much power you want but I can't imagine a boat of your size with less than a 35-hp motor. That is over 26 kilowatts. As to battery weight - no matter what type of lead acid battery you use (flooded, gel-cel, AGM) you are going to run close to a ton of batteries per hour of 35 hp-output run time. This also assumes a 100 percent depth of discharge (DOD) which kills batteries rapidly. A more conservative 50 percent DOD means at least 2 tons of batteries per hour of run time.

As to charging with solar panels: Peak output from solar panels is about 100 watts per square meter and that for only about 4 hours per day. To recharge the batteries after only one hour of motoring using 10 square meters of photovoltaics would require over 6 days.

The article also mentions using the system to generate power while sailing. I have heard that such a system would be at best 30 percent efficient. Imagine a propeller able to slow down your boat equivalent to a 5-hp motor. That would deliver enough power to recharge your batteries in about 25 hours of high-speed sailing. If you could reasonably expect that kind of wind, isn’t an engine superfluous?

As I have said, I love the idea of electric propulsion – Clean, quiet, instantaneous power! I have tried to figure it from every direction I can think of. But as Ian said electric motors are fine for short range flat water launches, but they fall down when trying to push 20 tons. Range and recharging are the issues. If the hype about fuel cells proves to be valid maybe electric propulsion is in our future, but I have read about “amazing new power sources on the horizon” far too often to get my hopes up. http://media5.hypernet.com/~dick/ubb/frown.gif

Frank Wentzel
02-28-2001, 11:21 AM
I just read the article on the Shadow power system. Regardless of the transmission used with your motor you still have the problem that the generation of 1 horsepower requires 750 watts. I don't know how much power you want but I can't imagine a boat of your size with less than a 35-hp motor. That is over 26 kilowatts. As to battery weight - no matter what type of lead acid battery you use (flooded, gel-cel, AGM) you are going to run close to a ton of batteries per hour of 35 hp-output run time. This also assumes a 100 percent depth of discharge (DOD) which kills batteries rapidly. A more conservative 50 percent DOD means at least 2 tons of batteries per hour of run time.

As to charging with solar panels: Peak output from solar panels is about 100 watts per square meter and that for only about 4 hours per day. To recharge the batteries after only one hour of motoring using 10 square meters of photovoltaics would require over 6 days.

The article also mentions using the system to generate power while sailing. I have heard that such a system would be at best 30 percent efficient. Imagine a propeller able to slow down your boat equivalent to a 5-hp motor. That would deliver enough power to recharge your batteries in about 25 hours of high-speed sailing. If you could reasonably expect that kind of wind, isn’t an engine superfluous?

As I have said, I love the idea of electric propulsion – Clean, quiet, instantaneous power! I have tried to figure it from every direction I can think of. But as Ian said electric motors are fine for short range flat water launches, but they fall down when trying to push 20 tons. Range and recharging are the issues. If the hype about fuel cells proves to be valid maybe electric propulsion is in our future, but I have read about “amazing new power sources on the horizon” far too often to get my hopes up. http://media5.hypernet.com/~dick/ubb/frown.gif

Frank Wentzel
02-28-2001, 11:21 AM
I just read the article on the Shadow power system. Regardless of the transmission used with your motor you still have the problem that the generation of 1 horsepower requires 750 watts. I don't know how much power you want but I can't imagine a boat of your size with less than a 35-hp motor. That is over 26 kilowatts. As to battery weight - no matter what type of lead acid battery you use (flooded, gel-cel, AGM) you are going to run close to a ton of batteries per hour of 35 hp-output run time. This also assumes a 100 percent depth of discharge (DOD) which kills batteries rapidly. A more conservative 50 percent DOD means at least 2 tons of batteries per hour of run time.

As to charging with solar panels: Peak output from solar panels is about 100 watts per square meter and that for only about 4 hours per day. To recharge the batteries after only one hour of motoring using 10 square meters of photovoltaics would require over 6 days.

The article also mentions using the system to generate power while sailing. I have heard that such a system would be at best 30 percent efficient. Imagine a propeller able to slow down your boat equivalent to a 5-hp motor. That would deliver enough power to recharge your batteries in about 25 hours of high-speed sailing. If you could reasonably expect that kind of wind, isn’t an engine superfluous?

As I have said, I love the idea of electric propulsion – Clean, quiet, instantaneous power! I have tried to figure it from every direction I can think of. But as Ian said electric motors are fine for short range flat water launches, but they fall down when trying to push 20 tons. Range and recharging are the issues. If the hype about fuel cells proves to be valid maybe electric propulsion is in our future, but I have read about “amazing new power sources on the horizon” far too often to get my hopes up. http://media5.hypernet.com/~dick/ubb/frown.gif

htom
02-28-2001, 12:37 PM
Part of the claimed efficiency is that the engine doesn't need a transmission at all (more properly speaking, it is, itself, an "infinite speed" transmission.)

"Meteor of Lune" is a little smaller, maybe, than Russ's 50' request.

They (Solomon) are using the same 750 Watt per horsepower as the rest of us. Some of their conversions are diesel / electric hybrid. One of them has a 500 pound battery package; doubtless some of the others are larger. They claim that their designs allow for a sailcraft to recharge her batteries at about a 3 to 1 rate (three hours of sailing provides one hour of motoring; details on speeds used I didn't find.) While it uses electricity, it's also different technology than is usually used.

htom
02-28-2001, 12:37 PM
Part of the claimed efficiency is that the engine doesn't need a transmission at all (more properly speaking, it is, itself, an "infinite speed" transmission.)

"Meteor of Lune" is a little smaller, maybe, than Russ's 50' request.

They (Solomon) are using the same 750 Watt per horsepower as the rest of us. Some of their conversions are diesel / electric hybrid. One of them has a 500 pound battery package; doubtless some of the others are larger. They claim that their designs allow for a sailcraft to recharge her batteries at about a 3 to 1 rate (three hours of sailing provides one hour of motoring; details on speeds used I didn't find.) While it uses electricity, it's also different technology than is usually used.

htom
02-28-2001, 12:37 PM
Part of the claimed efficiency is that the engine doesn't need a transmission at all (more properly speaking, it is, itself, an "infinite speed" transmission.)

"Meteor of Lune" is a little smaller, maybe, than Russ's 50' request.

They (Solomon) are using the same 750 Watt per horsepower as the rest of us. Some of their conversions are diesel / electric hybrid. One of them has a 500 pound battery package; doubtless some of the others are larger. They claim that their designs allow for a sailcraft to recharge her batteries at about a 3 to 1 rate (three hours of sailing provides one hour of motoring; details on speeds used I didn't find.) While it uses electricity, it's also different technology than is usually used.

RussG
03-01-2001, 08:39 AM
My last boat did not have an engine and I rarely missed it. My son and I always sailed on and off the mooring and beat (when necessary) in and out of the harbor. My need for an engine is mostly in dealing with mobility in fog and at night when in heavily trafficed waters. I would hate to find myself and crew becalmed in thick fog with the Nantucket ferry bearing down on us. I also would have occasion to maneuver in close quarters when approaching a crowded dock.

I suppoase I would also need it when going through the Cape Cod Canal or Wood's Hole in light air.

So my intent is a fairly minimal use of the engine. I like the idea of somehow using those batteries as internal ballast but I expect there are problems with that. Don't I have to worry about keeping them completely dry? And wouldn't it be dangerous to enclose the batteries in very small, water tight compartment? Obviously I am not yet knowledgeable in the use and care of batteries.

RussG
03-01-2001, 08:39 AM
My last boat did not have an engine and I rarely missed it. My son and I always sailed on and off the mooring and beat (when necessary) in and out of the harbor. My need for an engine is mostly in dealing with mobility in fog and at night when in heavily trafficed waters. I would hate to find myself and crew becalmed in thick fog with the Nantucket ferry bearing down on us. I also would have occasion to maneuver in close quarters when approaching a crowded dock.

I suppoase I would also need it when going through the Cape Cod Canal or Wood's Hole in light air.

So my intent is a fairly minimal use of the engine. I like the idea of somehow using those batteries as internal ballast but I expect there are problems with that. Don't I have to worry about keeping them completely dry? And wouldn't it be dangerous to enclose the batteries in very small, water tight compartment? Obviously I am not yet knowledgeable in the use and care of batteries.

RussG
03-01-2001, 08:39 AM
My last boat did not have an engine and I rarely missed it. My son and I always sailed on and off the mooring and beat (when necessary) in and out of the harbor. My need for an engine is mostly in dealing with mobility in fog and at night when in heavily trafficed waters. I would hate to find myself and crew becalmed in thick fog with the Nantucket ferry bearing down on us. I also would have occasion to maneuver in close quarters when approaching a crowded dock.

I suppoase I would also need it when going through the Cape Cod Canal or Wood's Hole in light air.

So my intent is a fairly minimal use of the engine. I like the idea of somehow using those batteries as internal ballast but I expect there are problems with that. Don't I have to worry about keeping them completely dry? And wouldn't it be dangerous to enclose the batteries in very small, water tight compartment? Obviously I am not yet knowledgeable in the use and care of batteries.

RussG
03-01-2001, 08:45 AM
And Scott, I appreciate your comment. My hoped for idea is to recharge the batteries without the use of fossil fuels. For example, I do not want a generator on board. Also, I prefer to be at anchor or mooring when visiting harbors. It is quieter, better for the boat, and gives me more of the sort of experience I am looking for when sailing. (I hope I am not sounding like a crabby hermit). So I do not anticipate relying on shore power.

RussG
03-01-2001, 08:45 AM
And Scott, I appreciate your comment. My hoped for idea is to recharge the batteries without the use of fossil fuels. For example, I do not want a generator on board. Also, I prefer to be at anchor or mooring when visiting harbors. It is quieter, better for the boat, and gives me more of the sort of experience I am looking for when sailing. (I hope I am not sounding like a crabby hermit). So I do not anticipate relying on shore power.

RussG
03-01-2001, 08:45 AM
And Scott, I appreciate your comment. My hoped for idea is to recharge the batteries without the use of fossil fuels. For example, I do not want a generator on board. Also, I prefer to be at anchor or mooring when visiting harbors. It is quieter, better for the boat, and gives me more of the sort of experience I am looking for when sailing. (I hope I am not sounding like a crabby hermit). So I do not anticipate relying on shore power.

Thad
03-01-2001, 11:45 AM
Talk to Andre' L. Dionne at the Electric Launch Company, 845-691-3777, www.electriclaunch.com (http://www.electriclaunch.com) / also electric motors are motors not engines -- motors go round and round while engines have parts that go back and forth (as I understand it)

Thad
03-01-2001, 11:45 AM
Talk to Andre' L. Dionne at the Electric Launch Company, 845-691-3777, www.electriclaunch.com (http://www.electriclaunch.com) / also electric motors are motors not engines -- motors go round and round while engines have parts that go back and forth (as I understand it)

Thad
03-01-2001, 11:45 AM
Talk to Andre' L. Dionne at the Electric Launch Company, 845-691-3777, www.electriclaunch.com (http://www.electriclaunch.com) / also electric motors are motors not engines -- motors go round and round while engines have parts that go back and forth (as I understand it)

paladin
03-01-2001, 12:33 PM
Thad is correct on his terminology....and
Frank....there's more than one way to skin this ..fish..
You are correct that the solar panels will only pump out their rated power for four hours ad day........if that's all you do..it is possible to charge those batteries under a 60 watt light bulb if you do it right.
The amount of light striking the solar panel will generate a finite voltage and supply a finite current at any light exposure....but not enough to charge the battery or overcome the voltage drop of the blocking diodes. It is far more efficient to use four each one-quarter size panels than one large one...but the solar panel manufacturer will not tell you this.
One way of getting ahead of the problem is a simple device called a dc-dc converter. At a small voltage, say 2 volts, it will switch and produce 14-15 volts but at small current, but enough to start trickle charging the battery. As the amount of light increases so does the available charging current until the maximum peak output is obtained. Most panels of reasonable size will generat 18 volts at about 3 amps. A good portion of this energy is wasted, or bypassed as being to large for the battery charger, the switcher improves the efficiency by switching the higher voltage to a lower charging voltage and a higher charging current, therefore increasing the efficiency of the system by about 20-25 percent.......this can be further increased by another sytem presently in build for production after about 3 years of testing all over the world.....sort of an extension of the above principle. The expected gains are on the order of 30 percent or better. The solar companies would not buy into this program as one manufacturer put it "we are in the business to sell solar panels, not enhance ones we have already sold". The company in the process of marketing this toy is a few miles from me. I worked on the testing and evaluation tests for a fgew months while working on the new boat....

paladin
03-01-2001, 12:33 PM
Thad is correct on his terminology....and
Frank....there's more than one way to skin this ..fish..
You are correct that the solar panels will only pump out their rated power for four hours ad day........if that's all you do..it is possible to charge those batteries under a 60 watt light bulb if you do it right.
The amount of light striking the solar panel will generate a finite voltage and supply a finite current at any light exposure....but not enough to charge the battery or overcome the voltage drop of the blocking diodes. It is far more efficient to use four each one-quarter size panels than one large one...but the solar panel manufacturer will not tell you this.
One way of getting ahead of the problem is a simple device called a dc-dc converter. At a small voltage, say 2 volts, it will switch and produce 14-15 volts but at small current, but enough to start trickle charging the battery. As the amount of light increases so does the available charging current until the maximum peak output is obtained. Most panels of reasonable size will generat 18 volts at about 3 amps. A good portion of this energy is wasted, or bypassed as being to large for the battery charger, the switcher improves the efficiency by switching the higher voltage to a lower charging voltage and a higher charging current, therefore increasing the efficiency of the system by about 20-25 percent.......this can be further increased by another sytem presently in build for production after about 3 years of testing all over the world.....sort of an extension of the above principle. The expected gains are on the order of 30 percent or better. The solar companies would not buy into this program as one manufacturer put it "we are in the business to sell solar panels, not enhance ones we have already sold". The company in the process of marketing this toy is a few miles from me. I worked on the testing and evaluation tests for a fgew months while working on the new boat....

paladin
03-01-2001, 12:33 PM
Thad is correct on his terminology....and
Frank....there's more than one way to skin this ..fish..
You are correct that the solar panels will only pump out their rated power for four hours ad day........if that's all you do..it is possible to charge those batteries under a 60 watt light bulb if you do it right.
The amount of light striking the solar panel will generate a finite voltage and supply a finite current at any light exposure....but not enough to charge the battery or overcome the voltage drop of the blocking diodes. It is far more efficient to use four each one-quarter size panels than one large one...but the solar panel manufacturer will not tell you this.
One way of getting ahead of the problem is a simple device called a dc-dc converter. At a small voltage, say 2 volts, it will switch and produce 14-15 volts but at small current, but enough to start trickle charging the battery. As the amount of light increases so does the available charging current until the maximum peak output is obtained. Most panels of reasonable size will generat 18 volts at about 3 amps. A good portion of this energy is wasted, or bypassed as being to large for the battery charger, the switcher improves the efficiency by switching the higher voltage to a lower charging voltage and a higher charging current, therefore increasing the efficiency of the system by about 20-25 percent.......this can be further increased by another sytem presently in build for production after about 3 years of testing all over the world.....sort of an extension of the above principle. The expected gains are on the order of 30 percent or better. The solar companies would not buy into this program as one manufacturer put it "we are in the business to sell solar panels, not enhance ones we have already sold". The company in the process of marketing this toy is a few miles from me. I worked on the testing and evaluation tests for a fgew months while working on the new boat....

Frank Wentzel
03-01-2001, 07:19 PM
Russ

Please excuse my earlier posts (especially the first) I spoke off the cuff and did not really run the numbers.

To your question about battery installations:

The batteries should not be exposed to salt water, aside from the obvious problem of corrosion of terminals and connectors, if salt water should enter the batteries they may emit chlorine gas (this used to be a submariner's concern). In most installations, this is not a problem as batteries are not normally stored in the bilge. If however you are using batteries as inside ballast over a large area of the bilge, there is the possibility that in heavy seas some of the batteries may become submerged. This could be more of a problem in an older carvel-planked hull that may take on considerable water in a seaway.

Lead acid batteries generate hydrogen gas during charging. There was a small explosion caused by this on a friend’s sailboat. He had three type 27 batteries in a fiberglass lined battery box that had a loose-fitting wooden lid. The explosion threw the lid off the box and the cases of all three batteries ruptured. A large battery bank would have to be well vented.

If you use flooded batteries (1/2 to 1/3 the cost of gel cell and AGM batteries) there is also the problem of air-borne acid mist during charging. This is not much of a problem for one or two batteries but becomes more of an issue for large battery banks. With the inclusion of forced air ventilation of your battery box(es), both acid-mist and hydrogen cease to be concerns. In addition, come to think of it, the enclosure that facilitates ventilation should also be able to eliminate the salt water/chlorine problem and keep your batteries dry.

The other question that needs to be addressed is how long do you want to be able to run and how many horsepower do you want at the prop. The new motor design discussed in the referenced website is definitely more efficient than using a high-speed motor and transmission. Efficiency is again improved through the use of a large, slow-rotation prop (though the large prop will do nothing good for your performance under sail). However, the performance the manufacturer boasts of (and of which I am very skeptical) is only possible if you are driving a light, “slippery” vessel. Assume all the inefficiencies claimed for the diesel engine are valid – lets say you only need 60 percent as many horsepower in an electric as you would in a diesel. Instead of 35 hp you would now need only 20 hp. You said you would like to be able to use the system in the Cape Cod Canal. I have never been there so I will need your help – would two hours be enough to traverse the canal? Two hours at twenty horsepower works out to 30-kilowatt hours. If we use a 144-volt system as recommended, that’s 208 amp/hours. Based on the best current battery technology and using a 50 percent DOD we need 96 electric vehicle batteries (110 amp/hour at 6 volts) or equivalent. This is two to three tons of batteries, but for a vessel in the 50-foot range, the weight should not be a problem (might volume be a problem?)

I must say I find the notion that 3 hours of sailing will provide enough power for one hour of motoring, as claimed by the motor manufacturer, very hard to accept.
The thermodynamic efficiency of the best theoretical heat engine is in the neighborhood of 35 percent. Then add the efficiency of energy conversion during the charging of lead acid batteries at 70 percent. It would seem that at best you could get 25 percent total conversion of energy into the battery. Unless by some magic they can exceed theoretical efficiency, it would be necessary to have over 35-hp input from the prop to charge the batteries in the three hours as they claim. They also say that you can do this charging game at 5 knots. But think of this – under what kind of conditions could you imagine being able to do 5 knots while a retarding force that yields 35 horsepower is working against you.


Chuck

I don’t mean to say that it is impossible to charge the batteries with photovoltaics and I am not trying to be unreasonably argumentative (although there are those who would be surprised to find me otherwise!). I used to work in the lead acid battery industry in battery design and testing. As I’ve said before I really like the idea of battery powered boats (and cars - but that’s a topic for another time). Nevertheless, the noble desire for clean power cannot make the recharging problem go away. If you want high-level motive power, you need a high-power recharging system. Once (if ever) photovoltaic cell prices drop, a 10 or 20kw array at your home may be feasible but on a boat there is not enough deck space

I was not aware that DC to DC converters of the required power levels were available and you are right, they will definitely improve efficiency. I strongly disagree with the photovoltaic cell manufacturer’s position. It seems clear that any improvement in system efficiency will improve the economics and thereby the viability and applicability of solar power systems. (I would love to see more information about this “toy” of which you speak.)

But even assuming 100 percent DC to DC conversion efficiency in the system under discussion - it still seems a long row to hoe. The panel you mentioned -18 volts at 3 amps - puts out 54 watts peak power. To account for off peak power output, let us say that peak power is produced for 7 hours per day rather than 4 hours. To provide recharging energy for two hours of propulsion as noted above (30 kW/hours), using 10 of these panels, 7.9 days would be required.

This does not take into account the losses when charging lead acid batteries. You need about 14.4 volts to charge a 12-volt battery (83.3% efficiency). Then only about 80 to 85 percent of the charge current is actually absorbed by the battery, the rest of the current goes into gassing and other losses. Therefore, only 70 percent of the energy input is converted into useable output. In the final analysis it still seems that to charge the battery bank in a reasonable time a prime mover will be required.

/// Frank ///

Frank Wentzel
03-01-2001, 07:19 PM
Russ

Please excuse my earlier posts (especially the first) I spoke off the cuff and did not really run the numbers.

To your question about battery installations:

The batteries should not be exposed to salt water, aside from the obvious problem of corrosion of terminals and connectors, if salt water should enter the batteries they may emit chlorine gas (this used to be a submariner's concern). In most installations, this is not a problem as batteries are not normally stored in the bilge. If however you are using batteries as inside ballast over a large area of the bilge, there is the possibility that in heavy seas some of the batteries may become submerged. This could be more of a problem in an older carvel-planked hull that may take on considerable water in a seaway.

Lead acid batteries generate hydrogen gas during charging. There was a small explosion caused by this on a friend’s sailboat. He had three type 27 batteries in a fiberglass lined battery box that had a loose-fitting wooden lid. The explosion threw the lid off the box and the cases of all three batteries ruptured. A large battery bank would have to be well vented.

If you use flooded batteries (1/2 to 1/3 the cost of gel cell and AGM batteries) there is also the problem of air-borne acid mist during charging. This is not much of a problem for one or two batteries but becomes more of an issue for large battery banks. With the inclusion of forced air ventilation of your battery box(es), both acid-mist and hydrogen cease to be concerns. In addition, come to think of it, the enclosure that facilitates ventilation should also be able to eliminate the salt water/chlorine problem and keep your batteries dry.

The other question that needs to be addressed is how long do you want to be able to run and how many horsepower do you want at the prop. The new motor design discussed in the referenced website is definitely more efficient than using a high-speed motor and transmission. Efficiency is again improved through the use of a large, slow-rotation prop (though the large prop will do nothing good for your performance under sail). However, the performance the manufacturer boasts of (and of which I am very skeptical) is only possible if you are driving a light, “slippery” vessel. Assume all the inefficiencies claimed for the diesel engine are valid – lets say you only need 60 percent as many horsepower in an electric as you would in a diesel. Instead of 35 hp you would now need only 20 hp. You said you would like to be able to use the system in the Cape Cod Canal. I have never been there so I will need your help – would two hours be enough to traverse the canal? Two hours at twenty horsepower works out to 30-kilowatt hours. If we use a 144-volt system as recommended, that’s 208 amp/hours. Based on the best current battery technology and using a 50 percent DOD we need 96 electric vehicle batteries (110 amp/hour at 6 volts) or equivalent. This is two to three tons of batteries, but for a vessel in the 50-foot range, the weight should not be a problem (might volume be a problem?)

I must say I find the notion that 3 hours of sailing will provide enough power for one hour of motoring, as claimed by the motor manufacturer, very hard to accept.
The thermodynamic efficiency of the best theoretical heat engine is in the neighborhood of 35 percent. Then add the efficiency of energy conversion during the charging of lead acid batteries at 70 percent. It would seem that at best you could get 25 percent total conversion of energy into the battery. Unless by some magic they can exceed theoretical efficiency, it would be necessary to have over 35-hp input from the prop to charge the batteries in the three hours as they claim. They also say that you can do this charging game at 5 knots. But think of this – under what kind of conditions could you imagine being able to do 5 knots while a retarding force that yields 35 horsepower is working against you.


Chuck

I don’t mean to say that it is impossible to charge the batteries with photovoltaics and I am not trying to be unreasonably argumentative (although there are those who would be surprised to find me otherwise!). I used to work in the lead acid battery industry in battery design and testing. As I’ve said before I really like the idea of battery powered boats (and cars - but that’s a topic for another time). Nevertheless, the noble desire for clean power cannot make the recharging problem go away. If you want high-level motive power, you need a high-power recharging system. Once (if ever) photovoltaic cell prices drop, a 10 or 20kw array at your home may be feasible but on a boat there is not enough deck space

I was not aware that DC to DC converters of the required power levels were available and you are right, they will definitely improve efficiency. I strongly disagree with the photovoltaic cell manufacturer’s position. It seems clear that any improvement in system efficiency will improve the economics and thereby the viability and applicability of solar power systems. (I would love to see more information about this “toy” of which you speak.)

But even assuming 100 percent DC to DC conversion efficiency in the system under discussion - it still seems a long row to hoe. The panel you mentioned -18 volts at 3 amps - puts out 54 watts peak power. To account for off peak power output, let us say that peak power is produced for 7 hours per day rather than 4 hours. To provide recharging energy for two hours of propulsion as noted above (30 kW/hours), using 10 of these panels, 7.9 days would be required.

This does not take into account the losses when charging lead acid batteries. You need about 14.4 volts to charge a 12-volt battery (83.3% efficiency). Then only about 80 to 85 percent of the charge current is actually absorbed by the battery, the rest of the current goes into gassing and other losses. Therefore, only 70 percent of the energy input is converted into useable output. In the final analysis it still seems that to charge the battery bank in a reasonable time a prime mover will be required.

/// Frank ///

Frank Wentzel
03-01-2001, 07:19 PM
Russ

Please excuse my earlier posts (especially the first) I spoke off the cuff and did not really run the numbers.

To your question about battery installations:

The batteries should not be exposed to salt water, aside from the obvious problem of corrosion of terminals and connectors, if salt water should enter the batteries they may emit chlorine gas (this used to be a submariner's concern). In most installations, this is not a problem as batteries are not normally stored in the bilge. If however you are using batteries as inside ballast over a large area of the bilge, there is the possibility that in heavy seas some of the batteries may become submerged. This could be more of a problem in an older carvel-planked hull that may take on considerable water in a seaway.

Lead acid batteries generate hydrogen gas during charging. There was a small explosion caused by this on a friend’s sailboat. He had three type 27 batteries in a fiberglass lined battery box that had a loose-fitting wooden lid. The explosion threw the lid off the box and the cases of all three batteries ruptured. A large battery bank would have to be well vented.

If you use flooded batteries (1/2 to 1/3 the cost of gel cell and AGM batteries) there is also the problem of air-borne acid mist during charging. This is not much of a problem for one or two batteries but becomes more of an issue for large battery banks. With the inclusion of forced air ventilation of your battery box(es), both acid-mist and hydrogen cease to be concerns. In addition, come to think of it, the enclosure that facilitates ventilation should also be able to eliminate the salt water/chlorine problem and keep your batteries dry.

The other question that needs to be addressed is how long do you want to be able to run and how many horsepower do you want at the prop. The new motor design discussed in the referenced website is definitely more efficient than using a high-speed motor and transmission. Efficiency is again improved through the use of a large, slow-rotation prop (though the large prop will do nothing good for your performance under sail). However, the performance the manufacturer boasts of (and of which I am very skeptical) is only possible if you are driving a light, “slippery” vessel. Assume all the inefficiencies claimed for the diesel engine are valid – lets say you only need 60 percent as many horsepower in an electric as you would in a diesel. Instead of 35 hp you would now need only 20 hp. You said you would like to be able to use the system in the Cape Cod Canal. I have never been there so I will need your help – would two hours be enough to traverse the canal? Two hours at twenty horsepower works out to 30-kilowatt hours. If we use a 144-volt system as recommended, that’s 208 amp/hours. Based on the best current battery technology and using a 50 percent DOD we need 96 electric vehicle batteries (110 amp/hour at 6 volts) or equivalent. This is two to three tons of batteries, but for a vessel in the 50-foot range, the weight should not be a problem (might volume be a problem?)

I must say I find the notion that 3 hours of sailing will provide enough power for one hour of motoring, as claimed by the motor manufacturer, very hard to accept.
The thermodynamic efficiency of the best theoretical heat engine is in the neighborhood of 35 percent. Then add the efficiency of energy conversion during the charging of lead acid batteries at 70 percent. It would seem that at best you could get 25 percent total conversion of energy into the battery. Unless by some magic they can exceed theoretical efficiency, it would be necessary to have over 35-hp input from the prop to charge the batteries in the three hours as they claim. They also say that you can do this charging game at 5 knots. But think of this – under what kind of conditions could you imagine being able to do 5 knots while a retarding force that yields 35 horsepower is working against you.


Chuck

I don’t mean to say that it is impossible to charge the batteries with photovoltaics and I am not trying to be unreasonably argumentative (although there are those who would be surprised to find me otherwise!). I used to work in the lead acid battery industry in battery design and testing. As I’ve said before I really like the idea of battery powered boats (and cars - but that’s a topic for another time). Nevertheless, the noble desire for clean power cannot make the recharging problem go away. If you want high-level motive power, you need a high-power recharging system. Once (if ever) photovoltaic cell prices drop, a 10 or 20kw array at your home may be feasible but on a boat there is not enough deck space

I was not aware that DC to DC converters of the required power levels were available and you are right, they will definitely improve efficiency. I strongly disagree with the photovoltaic cell manufacturer’s position. It seems clear that any improvement in system efficiency will improve the economics and thereby the viability and applicability of solar power systems. (I would love to see more information about this “toy” of which you speak.)

But even assuming 100 percent DC to DC conversion efficiency in the system under discussion - it still seems a long row to hoe. The panel you mentioned -18 volts at 3 amps - puts out 54 watts peak power. To account for off peak power output, let us say that peak power is produced for 7 hours per day rather than 4 hours. To provide recharging energy for two hours of propulsion as noted above (30 kW/hours), using 10 of these panels, 7.9 days would be required.

This does not take into account the losses when charging lead acid batteries. You need about 14.4 volts to charge a 12-volt battery (83.3% efficiency). Then only about 80 to 85 percent of the charge current is actually absorbed by the battery, the rest of the current goes into gassing and other losses. Therefore, only 70 percent of the energy input is converted into useable output. In the final analysis it still seems that to charge the battery bank in a reasonable time a prime mover will be required.

/// Frank ///

paladin
03-01-2001, 08:43 PM
Hi Frank,
I agree with your position...I wasn't arguing the numbers required or the energy required to recharge the batteries....but...Quite some time ago I saw an early design of Joel Whites....something like a 42 foot version of one of Sam Devlin's stitch and glue boats. Devlin uses a pair of 27 horepower deisels to propel the boat..........
and...just as an excercise one evening..and a what if.....I had run across an advertisement in the back of Cruising world or Woodenboat from an electric outdrive or saildrive manufacturer in the U.K. I started with the mid sized motors and using a square wave pulse converter to control the speed of the motors (the square wave would have supplied energy 50% of the time) I figure I could get at least 6 hours a day cruising at the required horsepower to make hull speed in calm water using 5 or six 8D batteries. Also..I had calculated that if I didn't try to hide a dink on the cabin top..I could get 28 each 65 watt solar panels on the overhead...and with the recharging thing-a ma-jigs could drive the system directly from the solar for 4-6 hours a day depending on the particular weather and place in the world and still charge the batteries. Now.....I will admit that there would be a helluva lot of batteries down below and this wouldn't be the most inexpensive boat in the world...but what the heck......it was a paperwork exercise. But you've gotta admit, it would make a nice short range cruiser for Sunday afternoon.....

paladin
03-01-2001, 08:43 PM
Hi Frank,
I agree with your position...I wasn't arguing the numbers required or the energy required to recharge the batteries....but...Quite some time ago I saw an early design of Joel Whites....something like a 42 foot version of one of Sam Devlin's stitch and glue boats. Devlin uses a pair of 27 horepower deisels to propel the boat..........
and...just as an excercise one evening..and a what if.....I had run across an advertisement in the back of Cruising world or Woodenboat from an electric outdrive or saildrive manufacturer in the U.K. I started with the mid sized motors and using a square wave pulse converter to control the speed of the motors (the square wave would have supplied energy 50% of the time) I figure I could get at least 6 hours a day cruising at the required horsepower to make hull speed in calm water using 5 or six 8D batteries. Also..I had calculated that if I didn't try to hide a dink on the cabin top..I could get 28 each 65 watt solar panels on the overhead...and with the recharging thing-a ma-jigs could drive the system directly from the solar for 4-6 hours a day depending on the particular weather and place in the world and still charge the batteries. Now.....I will admit that there would be a helluva lot of batteries down below and this wouldn't be the most inexpensive boat in the world...but what the heck......it was a paperwork exercise. But you've gotta admit, it would make a nice short range cruiser for Sunday afternoon.....

paladin
03-01-2001, 08:43 PM
Hi Frank,
I agree with your position...I wasn't arguing the numbers required or the energy required to recharge the batteries....but...Quite some time ago I saw an early design of Joel Whites....something like a 42 foot version of one of Sam Devlin's stitch and glue boats. Devlin uses a pair of 27 horepower deisels to propel the boat..........
and...just as an excercise one evening..and a what if.....I had run across an advertisement in the back of Cruising world or Woodenboat from an electric outdrive or saildrive manufacturer in the U.K. I started with the mid sized motors and using a square wave pulse converter to control the speed of the motors (the square wave would have supplied energy 50% of the time) I figure I could get at least 6 hours a day cruising at the required horsepower to make hull speed in calm water using 5 or six 8D batteries. Also..I had calculated that if I didn't try to hide a dink on the cabin top..I could get 28 each 65 watt solar panels on the overhead...and with the recharging thing-a ma-jigs could drive the system directly from the solar for 4-6 hours a day depending on the particular weather and place in the world and still charge the batteries. Now.....I will admit that there would be a helluva lot of batteries down below and this wouldn't be the most inexpensive boat in the world...but what the heck......it was a paperwork exercise. But you've gotta admit, it would make a nice short range cruiser for Sunday afternoon.....

Frank Wentzel
03-01-2001, 09:51 PM
Chuck

At the risk of endangering my reputation for being pig-headed, I have to say that I can see your point. I was thinking in terms of a more conventional sailboat design and looking at what you could “drop-in” in terms of electric auxiliary power. In other words, I was staying in the box. I agree a purpose-built boat has possibilities. Considering the lack of wind in many areas during the summer you would likely get more active time on the water using solar rather than sail. (I used to sail on Chesapeake Bay and mid summer was “shake n’ bake”.)

I would still like more info (from a curiosity viewpoint rather than purchase at this time) on the toys you mentioned. I first heard of them in communications satellite power systems: as battery cells failed the converters insured a consistent power source. I wasn’t aware of their use in other technologies.

/// Frank ///

Frank Wentzel
03-01-2001, 09:51 PM
Chuck

At the risk of endangering my reputation for being pig-headed, I have to say that I can see your point. I was thinking in terms of a more conventional sailboat design and looking at what you could “drop-in” in terms of electric auxiliary power. In other words, I was staying in the box. I agree a purpose-built boat has possibilities. Considering the lack of wind in many areas during the summer you would likely get more active time on the water using solar rather than sail. (I used to sail on Chesapeake Bay and mid summer was “shake n’ bake”.)

I would still like more info (from a curiosity viewpoint rather than purchase at this time) on the toys you mentioned. I first heard of them in communications satellite power systems: as battery cells failed the converters insured a consistent power source. I wasn’t aware of their use in other technologies.

/// Frank ///

Frank Wentzel
03-01-2001, 09:51 PM
Chuck

At the risk of endangering my reputation for being pig-headed, I have to say that I can see your point. I was thinking in terms of a more conventional sailboat design and looking at what you could “drop-in” in terms of electric auxiliary power. In other words, I was staying in the box. I agree a purpose-built boat has possibilities. Considering the lack of wind in many areas during the summer you would likely get more active time on the water using solar rather than sail. (I used to sail on Chesapeake Bay and mid summer was “shake n’ bake”.)

I would still like more info (from a curiosity viewpoint rather than purchase at this time) on the toys you mentioned. I first heard of them in communications satellite power systems: as battery cells failed the converters insured a consistent power source. I wasn’t aware of their use in other technologies.

/// Frank ///

Hesp
03-02-2001, 06:44 AM
Thought I'd look at the power requirement for my own boat - 27' 9000lb (4000kg). Seems a bit low, can anyone see a mistake?

Power required to push boat at certain speed + prop losses + motor losses = power required from battery.

Force to push boat at 5 knts (2.5m/s) = 85 lb (40kg or 400N - from computer).

Sorry, I'll have to do this in metric.

Power = force x speed = 400 x 2.5 = 1000W or 1KW

Lets say prop efficiency = 66%

Power at shaft = 1/0.66 = 1.5 KW

Lets say 90% motor efficiency, which I believe is now attainable

Power from battery = 1.5/0.9 = 1.7 KW

So at 12v current I = Power/Volts = 1700/12 = 142 Amps!!

Can I travel at 5knots for an hour with 2 (allowing for 50% discharge) 12v 150 Ahr batteries? That sounds fine for my requirements.

John.

Hesp
03-02-2001, 06:44 AM
Thought I'd look at the power requirement for my own boat - 27' 9000lb (4000kg). Seems a bit low, can anyone see a mistake?

Power required to push boat at certain speed + prop losses + motor losses = power required from battery.

Force to push boat at 5 knts (2.5m/s) = 85 lb (40kg or 400N - from computer).

Sorry, I'll have to do this in metric.

Power = force x speed = 400 x 2.5 = 1000W or 1KW

Lets say prop efficiency = 66%

Power at shaft = 1/0.66 = 1.5 KW

Lets say 90% motor efficiency, which I believe is now attainable

Power from battery = 1.5/0.9 = 1.7 KW

So at 12v current I = Power/Volts = 1700/12 = 142 Amps!!

Can I travel at 5knots for an hour with 2 (allowing for 50% discharge) 12v 150 Ahr batteries? That sounds fine for my requirements.

John.

Hesp
03-02-2001, 06:44 AM
Thought I'd look at the power requirement for my own boat - 27' 9000lb (4000kg). Seems a bit low, can anyone see a mistake?

Power required to push boat at certain speed + prop losses + motor losses = power required from battery.

Force to push boat at 5 knts (2.5m/s) = 85 lb (40kg or 400N - from computer).

Sorry, I'll have to do this in metric.

Power = force x speed = 400 x 2.5 = 1000W or 1KW

Lets say prop efficiency = 66%

Power at shaft = 1/0.66 = 1.5 KW

Lets say 90% motor efficiency, which I believe is now attainable

Power from battery = 1.5/0.9 = 1.7 KW

So at 12v current I = Power/Volts = 1700/12 = 142 Amps!!

Can I travel at 5knots for an hour with 2 (allowing for 50% discharge) 12v 150 Ahr batteries? That sounds fine for my requirements.

John.

htom
03-03-2001, 08:43 AM
I think you'd do better to have (say) four 75Ah batteries in series, and run the motor at 48VDC, to cut the I^2R losses (heat in the wiring between the batteries and motor). I suspect that's part of how Solomon etc are getting some of their efficiency.

htom
03-03-2001, 08:43 AM
I think you'd do better to have (say) four 75Ah batteries in series, and run the motor at 48VDC, to cut the I^2R losses (heat in the wiring between the batteries and motor). I suspect that's part of how Solomon etc are getting some of their efficiency.

htom
03-03-2001, 08:43 AM
I think you'd do better to have (say) four 75Ah batteries in series, and run the motor at 48VDC, to cut the I^2R losses (heat in the wiring between the batteries and motor). I suspect that's part of how Solomon etc are getting some of their efficiency.

Hesp
03-05-2001, 05:59 AM
Yes, in fact motors of the power required seem to run at at least 72v
http://www.electriclaunch.com/drives.html
and the Solomon at 144v I think
http://solomontechnologies.com/installs/301.htm

John

Hesp
03-05-2001, 05:59 AM
Yes, in fact motors of the power required seem to run at at least 72v
http://www.electriclaunch.com/drives.html
and the Solomon at 144v I think
http://solomontechnologies.com/installs/301.htm

John

Hesp
03-05-2001, 05:59 AM
Yes, in fact motors of the power required seem to run at at least 72v
http://www.electriclaunch.com/drives.html
and the Solomon at 144v I think
http://solomontechnologies.com/installs/301.htm

John

Bryan Mehus
03-06-2001, 04:09 AM
John,
How, or where did you obtain the "force required to push the boat at 5 knots"?


Slip of the propeller is directly proportional to the drag, i.e. zero drag zero slip, or 100% drag 100% slip. A lot of factors enter into the calculation of drag, including wetted surface area, hull shape, draught, windage etc. I don't know how to make this calculation, and would be interested in how you did it, as well as the "force required" calculation.
Thanks
Bryan

Bryan Mehus
03-06-2001, 04:09 AM
John,
How, or where did you obtain the "force required to push the boat at 5 knots"?


Slip of the propeller is directly proportional to the drag, i.e. zero drag zero slip, or 100% drag 100% slip. A lot of factors enter into the calculation of drag, including wetted surface area, hull shape, draught, windage etc. I don't know how to make this calculation, and would be interested in how you did it, as well as the "force required" calculation.
Thanks
Bryan

Bryan Mehus
03-06-2001, 04:09 AM
John,
How, or where did you obtain the "force required to push the boat at 5 knots"?


Slip of the propeller is directly proportional to the drag, i.e. zero drag zero slip, or 100% drag 100% slip. A lot of factors enter into the calculation of drag, including wetted surface area, hull shape, draught, windage etc. I don't know how to make this calculation, and would be interested in how you did it, as well as the "force required" calculation.
Thanks
Bryan

Bob Adams
03-06-2001, 10:41 PM
The USN has figured out how to move big boats with electric motors,now if I could just figure out where to put the damn reactor....

Bob Adams
03-06-2001, 10:41 PM
The USN has figured out how to move big boats with electric motors,now if I could just figure out where to put the damn reactor....

Bob Adams
03-06-2001, 10:41 PM
The USN has figured out how to move big boats with electric motors,now if I could just figure out where to put the damn reactor....

Frank Wentzel
03-06-2001, 10:59 PM
John

I am puzzled about the power level you believe is necessary to drive your 9,000 lb boat at 5 knots. I have a 28 foot Egret-type sharpie that dispaces about 3,500 lb. I use a 9.9 hp Honda in a well for auxiliary power. I have to run about 2/3 throttle to get 5 to 6 (estimated) knots. That sounds like at least twice the calculated power requirement for your 9,000 lb boat. (The question in my case is what percentage of rated horsepower does the Honda put out at 2/3 throttle.)

/// Frank ///

Frank Wentzel
03-06-2001, 10:59 PM
John

I am puzzled about the power level you believe is necessary to drive your 9,000 lb boat at 5 knots. I have a 28 foot Egret-type sharpie that dispaces about 3,500 lb. I use a 9.9 hp Honda in a well for auxiliary power. I have to run about 2/3 throttle to get 5 to 6 (estimated) knots. That sounds like at least twice the calculated power requirement for your 9,000 lb boat. (The question in my case is what percentage of rated horsepower does the Honda put out at 2/3 throttle.)

/// Frank ///

Frank Wentzel
03-06-2001, 10:59 PM
John

I am puzzled about the power level you believe is necessary to drive your 9,000 lb boat at 5 knots. I have a 28 foot Egret-type sharpie that dispaces about 3,500 lb. I use a 9.9 hp Honda in a well for auxiliary power. I have to run about 2/3 throttle to get 5 to 6 (estimated) knots. That sounds like at least twice the calculated power requirement for your 9,000 lb boat. (The question in my case is what percentage of rated horsepower does the Honda put out at 2/3 throttle.)

/// Frank ///

Hesp
03-07-2001, 04:34 AM
Bryan, I got the force required from the hull design software I use - Prolines 98. I chose a reasonable speed to give a low force (see below) and a round number for ease of calculation. Other forces at given speeds are:

1 knt 4 lb 2 kg 20 N
3.25knt 31 lb 14kg 140
5.4 110 lb 50kg 500
7 410 lb 185kg 1850
7.6 579 lb 262kg 2620

You can see why I chose 5knts, 7.6 knts requires 10 KW (14BHP) output from the prop. You can also see that large engines are for those who want to go that extra half Knot. All these figures are approximate, & I've done much rounding up/down, but they should give a good indication.


I got the prop efficiency from Skene's Elements of Yacht Design, Propellor Chart B (P141 in my edition). I must admit, you have cast doubt in my mind regarding this figure. For starters in my haste I wrongly chose an efficiency from the high end of the scale - they run from 0.3 to 0.7. A more reasonable figure might be 50 percent efficiency. Higher efficiency might be obtained on a power boat with a large, slow turning prop.
The chart is entered with a figure obtained using RPM, BHP & Hull speed. I assume (but I could be wrong) that 'efficiency' as quoted in the chart, is power out divided by power in. So although we then go on to calculate slip, it is already included in efficiency.

Frank, much depends on speed. As you can see from the figures above & in my previous post, at 5 knts we need a force of 400N, and if we increase the speed slightly to 5.4 knts we need 500N. 25 percent more force, and therefore power.
Also, without looking at a power curve for your outboard we don't know what power output you've got at a given RPM. And then, you can rev the 200 BHP engine in your SUV to max revs in nuetral, but it won't be producing much power.
Was the prop on the outboard selected to push a 3500lb 28' boat? Outboards tend to come with props designed for small boats, your prop might not be the most efficient for the job in hand.

When all's said and done, I got data from a computer program and a book, both well respected. They & I could be wrong.
Given the amount of pollution internal combustion engines in boats produce, I think this is an idea well worth persuing. No doubt the engine manufacturers will tell us it won't work, but I believe it's only a matter of time before we see a massive increase in the number of electric powered boats.

John

Hesp
03-07-2001, 04:34 AM
Bryan, I got the force required from the hull design software I use - Prolines 98. I chose a reasonable speed to give a low force (see below) and a round number for ease of calculation. Other forces at given speeds are:

1 knt 4 lb 2 kg 20 N
3.25knt 31 lb 14kg 140
5.4 110 lb 50kg 500
7 410 lb 185kg 1850
7.6 579 lb 262kg 2620

You can see why I chose 5knts, 7.6 knts requires 10 KW (14BHP) output from the prop. You can also see that large engines are for those who want to go that extra half Knot. All these figures are approximate, & I've done much rounding up/down, but they should give a good indication.


I got the prop efficiency from Skene's Elements of Yacht Design, Propellor Chart B (P141 in my edition). I must admit, you have cast doubt in my mind regarding this figure. For starters in my haste I wrongly chose an efficiency from the high end of the scale - they run from 0.3 to 0.7. A more reasonable figure might be 50 percent efficiency. Higher efficiency might be obtained on a power boat with a large, slow turning prop.
The chart is entered with a figure obtained using RPM, BHP & Hull speed. I assume (but I could be wrong) that 'efficiency' as quoted in the chart, is power out divided by power in. So although we then go on to calculate slip, it is already included in efficiency.

Frank, much depends on speed. As you can see from the figures above & in my previous post, at 5 knts we need a force of 400N, and if we increase the speed slightly to 5.4 knts we need 500N. 25 percent more force, and therefore power.
Also, without looking at a power curve for your outboard we don't know what power output you've got at a given RPM. And then, you can rev the 200 BHP engine in your SUV to max revs in nuetral, but it won't be producing much power.
Was the prop on the outboard selected to push a 3500lb 28' boat? Outboards tend to come with props designed for small boats, your prop might not be the most efficient for the job in hand.

When all's said and done, I got data from a computer program and a book, both well respected. They & I could be wrong.
Given the amount of pollution internal combustion engines in boats produce, I think this is an idea well worth persuing. No doubt the engine manufacturers will tell us it won't work, but I believe it's only a matter of time before we see a massive increase in the number of electric powered boats.

John

Hesp
03-07-2001, 04:34 AM
Bryan, I got the force required from the hull design software I use - Prolines 98. I chose a reasonable speed to give a low force (see below) and a round number for ease of calculation. Other forces at given speeds are:

1 knt 4 lb 2 kg 20 N
3.25knt 31 lb 14kg 140
5.4 110 lb 50kg 500
7 410 lb 185kg 1850
7.6 579 lb 262kg 2620

You can see why I chose 5knts, 7.6 knts requires 10 KW (14BHP) output from the prop. You can also see that large engines are for those who want to go that extra half Knot. All these figures are approximate, & I've done much rounding up/down, but they should give a good indication.


I got the prop efficiency from Skene's Elements of Yacht Design, Propellor Chart B (P141 in my edition). I must admit, you have cast doubt in my mind regarding this figure. For starters in my haste I wrongly chose an efficiency from the high end of the scale - they run from 0.3 to 0.7. A more reasonable figure might be 50 percent efficiency. Higher efficiency might be obtained on a power boat with a large, slow turning prop.
The chart is entered with a figure obtained using RPM, BHP & Hull speed. I assume (but I could be wrong) that 'efficiency' as quoted in the chart, is power out divided by power in. So although we then go on to calculate slip, it is already included in efficiency.

Frank, much depends on speed. As you can see from the figures above & in my previous post, at 5 knts we need a force of 400N, and if we increase the speed slightly to 5.4 knts we need 500N. 25 percent more force, and therefore power.
Also, without looking at a power curve for your outboard we don't know what power output you've got at a given RPM. And then, you can rev the 200 BHP engine in your SUV to max revs in nuetral, but it won't be producing much power.
Was the prop on the outboard selected to push a 3500lb 28' boat? Outboards tend to come with props designed for small boats, your prop might not be the most efficient for the job in hand.

When all's said and done, I got data from a computer program and a book, both well respected. They & I could be wrong.
Given the amount of pollution internal combustion engines in boats produce, I think this is an idea well worth persuing. No doubt the engine manufacturers will tell us it won't work, but I believe it's only a matter of time before we see a massive increase in the number of electric powered boats.

John

Hesp
03-07-2001, 04:37 AM
[This message has been edited by Hesp (edited 03-07-2001).]

Hesp
03-07-2001, 04:37 AM
[This message has been edited by Hesp (edited 03-07-2001).]

Hesp
03-07-2001, 04:37 AM
[This message has been edited by Hesp (edited 03-07-2001).]

Bryan Mehus
03-07-2001, 02:09 PM
John,
Looking at your examples, I can see how the "force required" figure can be so low. It is quite a curve i.e. over 200 times the force to go 7.6 times as fast. We all know that standing on a dock, you can push a 5 ton boat away by yourself, but if it is a house boat, and you're on the lee side of a light breeze, it is another matter.
I think that it may be wise to use a force figure based on the hull speed of the boat as the upper end of the speed requirement. Is your hull speed around 8 knts?

I could be wrong, but I believe that it would probably be more efficient to use a specially designed separate propeller to charge the battery bank. That is because the propeller designed to drive the boat will not work as well being driven.

If you are designing from scratch, how about using a variable frequency drive and a three phase induction motor. I remember(vaguely)a chart showing weights of various DC motor and drive combinations, compared to AC motor and drives with respect to electric vehicles. The DC units were twice the weight of the AC, and half the power. Since that particular research was done('80s)there have been great strides in the area of AC variable frequency drives. Then use a dedicated generator/prop,wind gen.,and solar system to charge the banks. Just some thoughts, that may be out to lunch!
BTW, first warm, sunny day of the century 4 us.
Bryan

Bryan Mehus
03-07-2001, 02:09 PM
John,
Looking at your examples, I can see how the "force required" figure can be so low. It is quite a curve i.e. over 200 times the force to go 7.6 times as fast. We all know that standing on a dock, you can push a 5 ton boat away by yourself, but if it is a house boat, and you're on the lee side of a light breeze, it is another matter.
I think that it may be wise to use a force figure based on the hull speed of the boat as the upper end of the speed requirement. Is your hull speed around 8 knts?

I could be wrong, but I believe that it would probably be more efficient to use a specially designed separate propeller to charge the battery bank. That is because the propeller designed to drive the boat will not work as well being driven.

If you are designing from scratch, how about using a variable frequency drive and a three phase induction motor. I remember(vaguely)a chart showing weights of various DC motor and drive combinations, compared to AC motor and drives with respect to electric vehicles. The DC units were twice the weight of the AC, and half the power. Since that particular research was done('80s)there have been great strides in the area of AC variable frequency drives. Then use a dedicated generator/prop,wind gen.,and solar system to charge the banks. Just some thoughts, that may be out to lunch!
BTW, first warm, sunny day of the century 4 us.
Bryan

Bryan Mehus
03-07-2001, 02:09 PM
John,
Looking at your examples, I can see how the "force required" figure can be so low. It is quite a curve i.e. over 200 times the force to go 7.6 times as fast. We all know that standing on a dock, you can push a 5 ton boat away by yourself, but if it is a house boat, and you're on the lee side of a light breeze, it is another matter.
I think that it may be wise to use a force figure based on the hull speed of the boat as the upper end of the speed requirement. Is your hull speed around 8 knts?

I could be wrong, but I believe that it would probably be more efficient to use a specially designed separate propeller to charge the battery bank. That is because the propeller designed to drive the boat will not work as well being driven.

If you are designing from scratch, how about using a variable frequency drive and a three phase induction motor. I remember(vaguely)a chart showing weights of various DC motor and drive combinations, compared to AC motor and drives with respect to electric vehicles. The DC units were twice the weight of the AC, and half the power. Since that particular research was done('80s)there have been great strides in the area of AC variable frequency drives. Then use a dedicated generator/prop,wind gen.,and solar system to charge the banks. Just some thoughts, that may be out to lunch!
BTW, first warm, sunny day of the century 4 us.
Bryan

Phil Young
03-08-2001, 11:33 PM
Honda have just brought a car onto the Australian market which is petrol/electric. Uses battery when they have enough juice. Uses petrol to generate electricity when need extra power or batteries are low. Recharges battery when coasting/slowing. Does not rely on external electricity input. I think the batteries are NiMH whatever that is rather than ordinary lead/acid. One just finished a promotional drive from Brisbane to Sydney I think, about 500miles, on 1 tank of petrol, 40 litres or so. Maybe the technology could be adapted, give it a few years and start hunting around the wreckers yards.

Phil Young
03-08-2001, 11:33 PM
Honda have just brought a car onto the Australian market which is petrol/electric. Uses battery when they have enough juice. Uses petrol to generate electricity when need extra power or batteries are low. Recharges battery when coasting/slowing. Does not rely on external electricity input. I think the batteries are NiMH whatever that is rather than ordinary lead/acid. One just finished a promotional drive from Brisbane to Sydney I think, about 500miles, on 1 tank of petrol, 40 litres or so. Maybe the technology could be adapted, give it a few years and start hunting around the wreckers yards.

Phil Young
03-08-2001, 11:33 PM
Honda have just brought a car onto the Australian market which is petrol/electric. Uses battery when they have enough juice. Uses petrol to generate electricity when need extra power or batteries are low. Recharges battery when coasting/slowing. Does not rely on external electricity input. I think the batteries are NiMH whatever that is rather than ordinary lead/acid. One just finished a promotional drive from Brisbane to Sydney I think, about 500miles, on 1 tank of petrol, 40 litres or so. Maybe the technology could be adapted, give it a few years and start hunting around the wreckers yards.

Dale Harvey
03-09-2001, 12:27 AM
If useing a sailing charge system, the prop shaft needs to run in an oil filled tube with thrust bearings and seals as opposed to the conventional rubber cutlass bearing. There was a company up in Maine makeing such a system for Lobsterboats. Advertised in National Fisherman. I think they patented it. The only current problem with fuel cells, is getting them to run only on gasoline. Currently the oil companies know that it would be far too easy to modify them run on water and cut them out of the loop. Again, the technology to solve all our problems is there, but the money pigs won't let us use it.

Dale Harvey
03-09-2001, 12:27 AM
If useing a sailing charge system, the prop shaft needs to run in an oil filled tube with thrust bearings and seals as opposed to the conventional rubber cutlass bearing. There was a company up in Maine makeing such a system for Lobsterboats. Advertised in National Fisherman. I think they patented it. The only current problem with fuel cells, is getting them to run only on gasoline. Currently the oil companies know that it would be far too easy to modify them run on water and cut them out of the loop. Again, the technology to solve all our problems is there, but the money pigs won't let us use it.

Dale Harvey
03-09-2001, 12:27 AM
If useing a sailing charge system, the prop shaft needs to run in an oil filled tube with thrust bearings and seals as opposed to the conventional rubber cutlass bearing. There was a company up in Maine makeing such a system for Lobsterboats. Advertised in National Fisherman. I think they patented it. The only current problem with fuel cells, is getting them to run only on gasoline. Currently the oil companies know that it would be far too easy to modify them run on water and cut them out of the loop. Again, the technology to solve all our problems is there, but the money pigs won't let us use it.

Ross Faneuf
03-09-2001, 08:29 AM
The drive system is the Evolution drive; they're located in Rockland ME. Quite expensive, but very well done. They're usually at the Maine boat show (2 weeks from today).

Ross Faneuf
03-09-2001, 08:29 AM
The drive system is the Evolution drive; they're located in Rockland ME. Quite expensive, but very well done. They're usually at the Maine boat show (2 weeks from today).

Ross Faneuf
03-09-2001, 08:29 AM
The drive system is the Evolution drive; they're located in Rockland ME. Quite expensive, but very well done. They're usually at the Maine boat show (2 weeks from today).

Hesp
03-13-2001, 08:43 AM
Bryan, I agree that it would be better to have a dedicated charging prop. Preferably one that could be used when conditions were right. The aquair http://www.ampair.com/ would be good but only produces a few amps. I have a self feathering Max prop to reduce drag whilst sailing - I wouldn't be happy when sailing upwind to divert some of the boat's motive power into electric generation. Downwind in a fresh breeze would be okay. Whilst I am a great fan of wind and solar power, it looks like the only way to recharge in hours rather than days/weeks is 110 or 240v mains (ideal if berthed in a marina), or an onboard generator.

Perhaps fuel cells hold the key. I believe that later this year Coleman are to market a portable fuel cell generator based on the Ballard fuel cell. I don't know what fuel it will use, and this might be an issue on a boat.

I like the idea of connecting the motor direct to the prop shaft - no gearbox with its (3%?) loss, expense and maintenance. But for max efficiency we need a slow turning prop, say 800-1000rpm. Although the Shadow Drive turns at a reasonable rpm, most motors will have max revs way above this I should imagine. I suppose one way round this would be to use an oversize motor which produced more torque at lower revs, but its an expensive option.

Bryan, you briefly touch on the advantages of AC over DC, if you can give more info on motors, or point me in the right direction it would be appreciated. As you will have guessed I have minimal knowledge of electric motors, but I think it is something worth looking into.

Yes, I did conveniently overlook the windage on the boat. And the force required to motor through oncoming waves. These forces would be added to the required motive force at a given boat speed. I am asking myself how an electric motor compares to having no engine, rather than how it compares to a diesel engine.

..........

Frank, is your Egret type sharpie a double ender? In an idle moment I drew a 28' double ended sharpie weighing 3500 lbs. At a given speed force required is - 1knot-5lbs, 2knt-9lbs, 3knt-22lbs, 4knt-48lbs, 5knt-88lbs, 6knt-158lbs, 7knt-264, 7.4knt-317lbs.

Phil, I think the hybrid car you refer to does can use mains to charge the batteries, and this is cheaper. But as you say there is petrol engine that charges the batteries. The engine runs at a constant speed for max efficiency. NiMh batteries are Nickel Metal hybrid, more expensive, but more watts hours per kg.
For those interested in pv solar panels, NiMh batteries, fuel cells and more, an interesting company is Energy Conversion Devices http://www.ovonics.com/

John.

Hesp
03-13-2001, 08:43 AM
Bryan, I agree that it would be better to have a dedicated charging prop. Preferably one that could be used when conditions were right. The aquair http://www.ampair.com/ would be good but only produces a few amps. I have a self feathering Max prop to reduce drag whilst sailing - I wouldn't be happy when sailing upwind to divert some of the boat's motive power into electric generation. Downwind in a fresh breeze would be okay. Whilst I am a great fan of wind and solar power, it looks like the only way to recharge in hours rather than days/weeks is 110 or 240v mains (ideal if berthed in a marina), or an onboard generator.

Perhaps fuel cells hold the key. I believe that later this year Coleman are to market a portable fuel cell generator based on the Ballard fuel cell. I don't know what fuel it will use, and this might be an issue on a boat.

I like the idea of connecting the motor direct to the prop shaft - no gearbox with its (3%?) loss, expense and maintenance. But for max efficiency we need a slow turning prop, say 800-1000rpm. Although the Shadow Drive turns at a reasonable rpm, most motors will have max revs way above this I should imagine. I suppose one way round this would be to use an oversize motor which produced more torque at lower revs, but its an expensive option.

Bryan, you briefly touch on the advantages of AC over DC, if you can give more info on motors, or point me in the right direction it would be appreciated. As you will have guessed I have minimal knowledge of electric motors, but I think it is something worth looking into.

Yes, I did conveniently overlook the windage on the boat. And the force required to motor through oncoming waves. These forces would be added to the required motive force at a given boat speed. I am asking myself how an electric motor compares to having no engine, rather than how it compares to a diesel engine.

..........

Frank, is your Egret type sharpie a double ender? In an idle moment I drew a 28' double ended sharpie weighing 3500 lbs. At a given speed force required is - 1knot-5lbs, 2knt-9lbs, 3knt-22lbs, 4knt-48lbs, 5knt-88lbs, 6knt-158lbs, 7knt-264, 7.4knt-317lbs.

Phil, I think the hybrid car you refer to does can use mains to charge the batteries, and this is cheaper. But as you say there is petrol engine that charges the batteries. The engine runs at a constant speed for max efficiency. NiMh batteries are Nickel Metal hybrid, more expensive, but more watts hours per kg.
For those interested in pv solar panels, NiMh batteries, fuel cells and more, an interesting company is Energy Conversion Devices http://www.ovonics.com/

John.

Hesp
03-13-2001, 08:43 AM
Bryan, I agree that it would be better to have a dedicated charging prop. Preferably one that could be used when conditions were right. The aquair http://www.ampair.com/ would be good but only produces a few amps. I have a self feathering Max prop to reduce drag whilst sailing - I wouldn't be happy when sailing upwind to divert some of the boat's motive power into electric generation. Downwind in a fresh breeze would be okay. Whilst I am a great fan of wind and solar power, it looks like the only way to recharge in hours rather than days/weeks is 110 or 240v mains (ideal if berthed in a marina), or an onboard generator.

Perhaps fuel cells hold the key. I believe that later this year Coleman are to market a portable fuel cell generator based on the Ballard fuel cell. I don't know what fuel it will use, and this might be an issue on a boat.

I like the idea of connecting the motor direct to the prop shaft - no gearbox with its (3%?) loss, expense and maintenance. But for max efficiency we need a slow turning prop, say 800-1000rpm. Although the Shadow Drive turns at a reasonable rpm, most motors will have max revs way above this I should imagine. I suppose one way round this would be to use an oversize motor which produced more torque at lower revs, but its an expensive option.

Bryan, you briefly touch on the advantages of AC over DC, if you can give more info on motors, or point me in the right direction it would be appreciated. As you will have guessed I have minimal knowledge of electric motors, but I think it is something worth looking into.

Yes, I did conveniently overlook the windage on the boat. And the force required to motor through oncoming waves. These forces would be added to the required motive force at a given boat speed. I am asking myself how an electric motor compares to having no engine, rather than how it compares to a diesel engine.

..........

Frank, is your Egret type sharpie a double ender? In an idle moment I drew a 28' double ended sharpie weighing 3500 lbs. At a given speed force required is - 1knot-5lbs, 2knt-9lbs, 3knt-22lbs, 4knt-48lbs, 5knt-88lbs, 6knt-158lbs, 7knt-264, 7.4knt-317lbs.

Phil, I think the hybrid car you refer to does can use mains to charge the batteries, and this is cheaper. But as you say there is petrol engine that charges the batteries. The engine runs at a constant speed for max efficiency. NiMh batteries are Nickel Metal hybrid, more expensive, but more watts hours per kg.
For those interested in pv solar panels, NiMh batteries, fuel cells and more, an interesting company is Energy Conversion Devices http://www.ovonics.com/

John.