Here's a weird question, with the increasing popurlarity of HEV's on the road (hybred electric vehicles) is there growing interest towards making sailboats with the same power train? A small generator that powers a large bank of batteries when they become low and an electric motor that runs the prop. Seems to me if you add some extra charging methods such as a wind generator and solar panels you could, in theory, motor/sail thousands of miles on just a small amount of fuel. Maybe on my next re-power I'll give it a try. Hopefully that wont be for a long while since I only have 1300 hours on my current engine.
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Gordon Torresen
Hybrid
You don't get something for nothing! If you consider that the smallest diesels put out about 6 HP, you would have to have a big boat to carry the batteries. I have not followed the progress of HEV's, but it seems that if it was smart, it would be moving faster. I hope there is an electrical engineer looking in that can can tell us how long how much battery will last at a given horsepower.
You don't get something for nothing! If you consider that the smallest diesels put out about 6 HP, you would have to have a big boat to carry the batteries. I have not followed the progress of HEV's, but it seems that if it was smart, it would be moving faster. I hope there is an electrical engineer looking in that can can tell us how long how much battery will last at a given horsepower.
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bill walton
along these lines
I've been intently following the progress of fuel cells for the past year or so. It appears that a unit capable of supplying power for a house in in the offing from GE next year while Ballard is around the corner from a unit capable of being produced in automotive quantities and small units for powering electronics is due out from several vendors next year. I'm hoping that one capable of replacing my genset will be around by 2004, my retirement and Caribbean date.
I've been intently following the progress of fuel cells for the past year or so. It appears that a unit capable of supplying power for a house in in the offing from GE next year while Ballard is around the corner from a unit capable of being produced in automotive quantities and small units for powering electronics is due out from several vendors next year. I'm hoping that one capable of replacing my genset will be around by 2004, my retirement and Caribbean date.
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Tim
1 hp = 0.7457 kiloWatt
Auto HEVs work on the principle that most of the time, a car's gasoline motor is oversized for its job. At steady highway speeds, the car is using 20% or less of its available power; the rest of the power is only used during hard acceleration. For an HEV, the gas motor is much smaller and the electric motor acts as a "booster" to get up to speed. The problem with boats is that for displacement hulls (sailboats,) the steady speed power requirement is just about exactly the full power. The net effect is, to replace a 12HP diesel, you need a generator with about a 12HP diesel running it. The win from fuel cells comes from the possibility that they can be quite small and very quiet. Of course the ones sold now are extremely expensive, very large (the GE is 7 kW and about the size of a large side-by-side refrigerator), and run off straight hydrogen or "cracked" CNG, neither of which is a very compact fuel to carry. I'm guessing that in 2-5 years you'll see fuel cells running off convential fuels that would work in a small sailboat, probably gasoline. At that point, I would expect to see diesel motors start to go away as sailboat auxiliaries if for no other reasons than noise, weight and space.
Auto HEVs work on the principle that most of the time, a car's gasoline motor is oversized for its job. At steady highway speeds, the car is using 20% or less of its available power; the rest of the power is only used during hard acceleration. For an HEV, the gas motor is much smaller and the electric motor acts as a "booster" to get up to speed. The problem with boats is that for displacement hulls (sailboats,) the steady speed power requirement is just about exactly the full power. The net effect is, to replace a 12HP diesel, you need a generator with about a 12HP diesel running it. The win from fuel cells comes from the possibility that they can be quite small and very quiet. Of course the ones sold now are extremely expensive, very large (the GE is 7 kW and about the size of a large side-by-side refrigerator), and run off straight hydrogen or "cracked" CNG, neither of which is a very compact fuel to carry. I'm guessing that in 2-5 years you'll see fuel cells running off convential fuels that would work in a small sailboat, probably gasoline. At that point, I would expect to see diesel motors start to go away as sailboat auxiliaries if for no other reasons than noise, weight and space.
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Ernie Rodriguez
Electric Motors
There is a company in Maryland called "Solomon Technologies" that makes an electric motor for use in a sailboat. They currently are producing two sizes, a six HP unit and a ten HP unit. The motor is a unique design, it is called the Electric Wheel. It was originally designed for use in electric vehicles where the motor was going to be built right into the wheel, thus eliminating drive shaft, transmissions, etc. The auto companies didn't pick up on it, but the inventor of the motor has installed it in several sailboats. While undersail the motor is capable of generating power and can recharge the batteries. A typical application would require about ten batteries in series to develop about 120 volts. Torque characteristics of the motor is flat from zero to 1200 RPM, and does not need a transmission as the shaft rpm is about the right amount for a typical propellor. I have looked at this as an alternative to my present Yanmar 3GMD, but its hard to beat. For one thing, according to the standard propellor sizing equations, I need at least 20 hp of engine power for a propellor that can deliver an efficiency 0f 55% in order to acheive hull speed (1.2*Sq Root of waterline). I haven't found one yet, most end up being in the 40 to 45 range. So with the ten hp motor, the best I could do would be less than hull speed. Neverthless, the concept sounds attractive, and when the fuel cells are developed to the point of being practical, this may be the way to go. But for the present, its hard to beat the energy density of a diesel engine. If anyone is interested in this, contact David Tether at ewhel@aol.com for further info. Ernie
There is a company in Maryland called "Solomon Technologies" that makes an electric motor for use in a sailboat. They currently are producing two sizes, a six HP unit and a ten HP unit. The motor is a unique design, it is called the Electric Wheel. It was originally designed for use in electric vehicles where the motor was going to be built right into the wheel, thus eliminating drive shaft, transmissions, etc. The auto companies didn't pick up on it, but the inventor of the motor has installed it in several sailboats. While undersail the motor is capable of generating power and can recharge the batteries. A typical application would require about ten batteries in series to develop about 120 volts. Torque characteristics of the motor is flat from zero to 1200 RPM, and does not need a transmission as the shaft rpm is about the right amount for a typical propellor. I have looked at this as an alternative to my present Yanmar 3GMD, but its hard to beat. For one thing, according to the standard propellor sizing equations, I need at least 20 hp of engine power for a propellor that can deliver an efficiency 0f 55% in order to acheive hull speed (1.2*Sq Root of waterline). I haven't found one yet, most end up being in the 40 to 45 range. So with the ten hp motor, the best I could do would be less than hull speed. Neverthless, the concept sounds attractive, and when the fuel cells are developed to the point of being practical, this may be the way to go. But for the present, its hard to beat the energy density of a diesel engine. If anyone is interested in this, contact David Tether at ewhel@aol.com for further info. Ernie
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Tim
oh, the answer is....
So say a 6HP motor is sufficient: 6HP / 0.7457 = 8 kWatts 8kWatts / 12V = 670Amps Lets say you're running the motor for 2 hours a week (not much...): 670A x 2 Hours = 1340 Amp-hours Say you can run your deep cycle batteries down to 50% capacity as recommended: 1340 Ah / 50% = 2680 Ahs of battery and lets say you buy Rolls 12V group 27s: 1340Ah/112Ah per battery = 12 batteries 12 batteries x 44 lbs each = 528 lbs 12 batteries x $148 each = $1776 So lets say you want to recharge those batteries with solar cells over a week and you live near Boston and get the equivalent of about 5 solar hours a day in the summer: 670 Ah / (5 hours/day * 7 days ) = 19 Amps of solar cells. and you buy Unisolar USF64s from Solar Electric Inc: 19 A / 4A per panel = 5 panels 5 panels x $289 per panel = $1445 5 panels x 11.25 sq feet = 56 sq feet and of course a 20A charge controller. Not very practical.
So say a 6HP motor is sufficient: 6HP / 0.7457 = 8 kWatts 8kWatts / 12V = 670Amps Lets say you're running the motor for 2 hours a week (not much...): 670A x 2 Hours = 1340 Amp-hours Say you can run your deep cycle batteries down to 50% capacity as recommended: 1340 Ah / 50% = 2680 Ahs of battery and lets say you buy Rolls 12V group 27s: 1340Ah/112Ah per battery = 12 batteries 12 batteries x 44 lbs each = 528 lbs 12 batteries x $148 each = $1776 So lets say you want to recharge those batteries with solar cells over a week and you live near Boston and get the equivalent of about 5 solar hours a day in the summer: 670 Ah / (5 hours/day * 7 days ) = 19 Amps of solar cells. and you buy Unisolar USF64s from Solar Electric Inc: 19 A / 4A per panel = 5 panels 5 panels x $289 per panel = $1445 5 panels x 11.25 sq feet = 56 sq feet and of course a 20A charge controller. Not very practical.
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