A thought, Can we put a 115 VAC generator on our inboard motors and make plenty of power under way?
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yes but....
There are a few issues. 1) you would need some kind of special electronic pulley on the generator (kind of like the pulley on a car AC compressor) so that you can turn it off when you don't want the drag on the engine...aka...while you are doing normal motoring. 2) you must understand that this is not the proper use of your engine. You will be running your engine at a much lower RPM and under light load. Your engine isn't designed for this for long periods, so don't think your going to use this setup to run the AC or heater all night long because you will develop a carbon buildup inside your engine. 3) You will burn a lot more fuel then you would with a proper engine for the generator. 4) You will need to figure out the proper RPMs to run the engine at so that the generator pulley rotates at the right speed. This would be determined by the size of the pulley on the engine. 5) Generators need to be cooled by a fresh flow of air. Most engine compartments are designed to keep noise in, not let a large flow of air in. Keeping the generator cool would be a challenge.
There are a few issues. 1) you would need some kind of special electronic pulley on the generator (kind of like the pulley on a car AC compressor) so that you can turn it off when you don't want the drag on the engine...aka...while you are doing normal motoring. 2) you must understand that this is not the proper use of your engine. You will be running your engine at a much lower RPM and under light load. Your engine isn't designed for this for long periods, so don't think your going to use this setup to run the AC or heater all night long because you will develop a carbon buildup inside your engine. 3) You will burn a lot more fuel then you would with a proper engine for the generator. 4) You will need to figure out the proper RPMs to run the engine at so that the generator pulley rotates at the right speed. This would be determined by the size of the pulley on the engine. 5) Generators need to be cooled by a fresh flow of air. Most engine compartments are designed to keep noise in, not let a large flow of air in. Keeping the generator cool would be a challenge.
Seen it done - but
I have seen both PTO and belt driven installations. However, I have no actual experience and can't comment on how wise this would be. Same load on the engine as common engine driven refrigeration? - dunno. Also, don't know if RPM is always an issue, but here are some FAQs for a particlular manufacturer: http://mastersalesonline.com/voltbelt/questions.html BTW - my AC power needs are considerably less when I am under way than when I am at anchor, and I don't like to run the engine unless I'm using it to move the boat.
I have seen both PTO and belt driven installations. However, I have no actual experience and can't comment on how wise this would be. Same load on the engine as common engine driven refrigeration? - dunno. Also, don't know if RPM is always an issue, but here are some FAQs for a particlular manufacturer: http://mastersalesonline.com/voltbelt/questions.html BTW - my AC power needs are considerably less when I am under way than when I am at anchor, and I don't like to run the engine unless I'm using it to move the boat.
Why would you want to?
As with all electrical issues, it isn't possible to give a good answer or advice without knowing any details. If you absolutely have to have a lot of AC power, whether underway or at anchor or mooring, a stand-alone generator is probably the best choice - they are built for the purpose. If you only need a reasonable amount of AC power, use a DC/AC inverter. There are plenty of sizes available, they run off the batteries you already (presumably) have, and the batteries can be re-charged by any combination of alternator/charger/windvane/solar/towed sources. Again, if you provide specifics, you'll get more useful answers/advice. Cheers, Bob s/v X SAIL R 8
As with all electrical issues, it isn't possible to give a good answer or advice without knowing any details. If you absolutely have to have a lot of AC power, whether underway or at anchor or mooring, a stand-alone generator is probably the best choice - they are built for the purpose. If you only need a reasonable amount of AC power, use a DC/AC inverter. There are plenty of sizes available, they run off the batteries you already (presumably) have, and the batteries can be re-charged by any combination of alternator/charger/windvane/solar/towed sources. Again, if you provide specifics, you'll get more useful answers/advice. Cheers, Bob s/v X SAIL R 8
Hi Tony, we have a three cylinder Cummins...
(Kubota) diesel that is dedicated to an eight kilowatt AC generator on our boat. Some additional things to consider: 1. Our Genset engine is governed to deliver the precise RPMs to the direct drive integrated AC generator in order to produce 120 volts AC. Most all gensets that I've seen are set up this way. Not such a good idea for a propulsion engine. Once you start the Genset it accelerates immediately to the preset RPM. 2. Although it is set for a specific RPM (around 1500 I think), I do not believe this does any harm to the engine as long as you work it, which the owner's manual recommends (truck, transit and other industrial diesels commonly operate in this RPM range). So what I do when we're cruising is to run it for two hours minimum, during which I have the hot water heater on for cleaning and bathing (about ten amps), plus it is bulk charging the house bank (25-30 amps). At least for the first hour the engine is working pretty hard until the hot water reaches its set temp and the charger completes the bulk charge cycle. 3. The 2GM on your boat has enough power to run a smaller generator, but then you would need to come up with a mechanism that would allow you to engage and disengage the appliance, plus operate it at the precise RPM to give you the 120 volts AC that you want/need. Please let us know what you decide. Terry
(Kubota) diesel that is dedicated to an eight kilowatt AC generator on our boat. Some additional things to consider: 1. Our Genset engine is governed to deliver the precise RPMs to the direct drive integrated AC generator in order to produce 120 volts AC. Most all gensets that I've seen are set up this way. Not such a good idea for a propulsion engine. Once you start the Genset it accelerates immediately to the preset RPM. 2. Although it is set for a specific RPM (around 1500 I think), I do not believe this does any harm to the engine as long as you work it, which the owner's manual recommends (truck, transit and other industrial diesels commonly operate in this RPM range). So what I do when we're cruising is to run it for two hours minimum, during which I have the hot water heater on for cleaning and bathing (about ten amps), plus it is bulk charging the house bank (25-30 amps). At least for the first hour the engine is working pretty hard until the hot water reaches its set temp and the charger completes the bulk charge cycle. 3. The 2GM on your boat has enough power to run a smaller generator, but then you would need to come up with a mechanism that would allow you to engage and disengage the appliance, plus operate it at the precise RPM to give you the 120 volts AC that you want/need. Please let us know what you decide. Terry
Loads --> gen size --> engine size
What is your max AC load? How long does that load run? AS a general rule heating water with an AC heating element powered by a generator being driven by a water cooled engine is a dumb idea. Using the engine cooling water is more economical. Also using AC to power a stove is not recommended due to the VERY high load is creates. The size generator you need is impractical till you get in the 50' boat range. A fuel type stove is much more economical. If you want to power electronics then you really have a problem as you are stuck with using a generator. An inveter will not give true sine wave pure AC voltage and most AC electronics (and some wall wart ac-dc devices too) will not be happy on a diet of square wave AC. AC generators are great for powering.......... well what on a boat actually needs AC. There are DC alternatives for most things. RV shops have 12 volt just about everything. Even saw a blender once.
What is your max AC load? How long does that load run? AS a general rule heating water with an AC heating element powered by a generator being driven by a water cooled engine is a dumb idea. Using the engine cooling water is more economical. Also using AC to power a stove is not recommended due to the VERY high load is creates. The size generator you need is impractical till you get in the 50' boat range. A fuel type stove is much more economical. If you want to power electronics then you really have a problem as you are stuck with using a generator. An inveter will not give true sine wave pure AC voltage and most AC electronics (and some wall wart ac-dc devices too) will not be happy on a diet of square wave AC. AC generators are great for powering.......... well what on a boat actually needs AC. There are DC alternatives for most things. RV shops have 12 volt just about everything. Even saw a blender once.
AC Power Under Way
Tony, To generate 60 Hz you will need to run the engine at a fixed rpm. Most devices which consume AC need a frequency close to this - or 50 Hz in European waters. This will either mean motoring at a pre-determined speed or, if you intend to run the engine out of gear whilst sailing, please remember the engine is not to be run at more than 15° of heel else the oil pickup in the sump may run dry and seize the engine. I looked into this quite seriously for making AC power whilst on an anchor - even scrounged the alternator, but I didn't go ahead with the project. Instead I fitted a high rate alternator controller to the OEM 55amp 12 v unit and also installed a static inverter. Now we run just about everything from the house batteries, eg. hair dryer, electric iron, toaster etc and only run the engine when we need the microwave as it takes 75 amps from the 12 V side. Running the engine pokes in 55 amps so there is only a nett drain of 20 amps. Most microwave cooking is done in ten minutes so running the engine is no problem and little nuisance. BTW nowadays many inverters are pure sine wave so okay for even the most sensitive electronics and TVs etc. Even my old Heart modified sine wave runs everything perfectly well though I would not recommend a square wave unit for electronic equipment, but I have not seen one on the market for years anyway.
Tony, To generate 60 Hz you will need to run the engine at a fixed rpm. Most devices which consume AC need a frequency close to this - or 50 Hz in European waters. This will either mean motoring at a pre-determined speed or, if you intend to run the engine out of gear whilst sailing, please remember the engine is not to be run at more than 15° of heel else the oil pickup in the sump may run dry and seize the engine. I looked into this quite seriously for making AC power whilst on an anchor - even scrounged the alternator, but I didn't go ahead with the project. Instead I fitted a high rate alternator controller to the OEM 55amp 12 v unit and also installed a static inverter. Now we run just about everything from the house batteries, eg. hair dryer, electric iron, toaster etc and only run the engine when we need the microwave as it takes 75 amps from the 12 V side. Running the engine pokes in 55 amps so there is only a nett drain of 20 amps. Most microwave cooking is done in ten minutes so running the engine is no problem and little nuisance. BTW nowadays many inverters are pure sine wave so okay for even the most sensitive electronics and TVs etc. Even my old Heart modified sine wave runs everything perfectly well though I would not recommend a square wave unit for electronic equipment, but I have not seen one on the market for years anyway.
Hi Bill, I'm not sure what data you base your...
conclusions on, but to me running our 4JH propulsion engine for an hour that will consume about 1.5 gallons of fuel just to produce hot water, when the Genset can do it in the same amount of time, but consume about one half gallon of fuel, seems more economical. We use the inverter quite a bit while on the hook to power several AC appliances (microwave, TV/VCR, Walmart DVD player, stereo system, etc.) and in the past five years we have yet to have any of these units fail. Maybe some day they will, but I question whether it will be a result of operating them via the inverter. Ours is a 1991 model and all of the equipment (except for the DVD player) is original. As far as AC goes it has its place on a boat. Our boat came equipped with dual reverse cycle heat pumps. Maybe there is a DC or fuel version made, but these units are pretty efficient and do require AC to operate. Me thinks Hunter did the right thing in the systems they put together for this boat. At least I'm happy with the end product. Terry P.S. You are right that fuel stoves do a better job on a boat than AC.
conclusions on, but to me running our 4JH propulsion engine for an hour that will consume about 1.5 gallons of fuel just to produce hot water, when the Genset can do it in the same amount of time, but consume about one half gallon of fuel, seems more economical. We use the inverter quite a bit while on the hook to power several AC appliances (microwave, TV/VCR, Walmart DVD player, stereo system, etc.) and in the past five years we have yet to have any of these units fail. Maybe some day they will, but I question whether it will be a result of operating them via the inverter. Ours is a 1991 model and all of the equipment (except for the DVD player) is original. As far as AC goes it has its place on a boat. Our boat came equipped with dual reverse cycle heat pumps. Maybe there is a DC or fuel version made, but these units are pretty efficient and do require AC to operate. Me thinks Hunter did the right thing in the systems they put together for this boat. At least I'm happy with the end product. Terry P.S. You are right that fuel stoves do a better job on a boat than AC.
Thanks for allthe advice
Thanks, I have plenty to concider here. Only real want is to make hot water. I don't want to refit the boat for propane ant eh the 2GM can't make enough watts to heat water. So, I was thinking of using one of those electric demand heaters. They are small and easy to install. The rub is they use lots of amps.
Thanks, I have plenty to concider here. Only real want is to make hot water. I don't want to refit the boat for propane ant eh the 2GM can't make enough watts to heat water. So, I was thinking of using one of those electric demand heaters. They are small and easy to install. The rub is they use lots of amps.
Actually, it can...
I have a Yanmar 2GM20F in my '87H31 with a hot water heater hooked up to the engine (it's a coil that runs through the heat exchanger, I think - NOT electrical). After motoring for a while (I can't give an exact number, but 30 minutes is plenty, maybe less) the hot water tank is full of scalding water...... and it's still hot the next morning (but not scalding). If it's just hot water you're looking for, check out the 'solar shower' thingies.... they're just black bags you leave in the sun, and in a few hours they provide enough hot water for a shower. I can't quite come to grips with the idea of using precious DC amps to heat water. Most sailors work hard to conserve their battery power and limit the depth of discharge, which plays a major role in prolonging battery life. Squandering it on hot water seems almost like a 'sin'.
Again, if you give us more details, we can give better advice. Cheers, Bob s/v X SAIL R 8
I have a Yanmar 2GM20F in my '87H31 with a hot water heater hooked up to the engine (it's a coil that runs through the heat exchanger, I think - NOT electrical). After motoring for a while (I can't give an exact number, but 30 minutes is plenty, maybe less) the hot water tank is full of scalding water...... and it's still hot the next morning (but not scalding). If it's just hot water you're looking for, check out the 'solar shower' thingies.... they're just black bags you leave in the sun, and in a few hours they provide enough hot water for a shower. I can't quite come to grips with the idea of using precious DC amps to heat water. Most sailors work hard to conserve their battery power and limit the depth of discharge, which plays a major role in prolonging battery life. Squandering it on hot water seems almost like a 'sin'.
Again, if you give us more details, we can give better advice. Cheers, Bob s/v X SAIL R 8Bob W. is right on
The water in the conventional heater will scald you. Remember, this is hot water for consumption, not the raw water feed to the engine. You don't stipulate how old your boat is, but it's entirely possible the hot water heater is rusted out or the element is shot. Either is easily fixable. Ask the guy in the next slip for how the thing works. Rather brilliant, actually.
The water in the conventional heater will scald you. Remember, this is hot water for consumption, not the raw water feed to the engine. You don't stipulate how old your boat is, but it's entirely possible the hot water heater is rusted out or the element is shot. Either is easily fixable. Ask the guy in the next slip for how the thing works. Rather brilliant, actually.
Tony, if your engine is raw water cooled
you can't use it to heat a marine hot water heater. But they make propane 'instant' water heaters! Oh no, wait, you don't have propane. Never mind.
you can't use it to heat a marine hot water heater. But they make propane 'instant' water heaters! Oh no, wait, you don't have propane. Never mind.
2GM20F is fresh-water cooled....
with a raw-water intake and heat exchanger.... just like the big engines! Cheers, Bob s/v X SAIL R 8
with a raw-water intake and heat exchanger.... just like the big engines! Cheers, Bob s/v X SAIL R 8
Thanks all
The solution to this little problem will make someone wealthy. We have a 2GM. It's raw water cooled. It's 30+ years old and I have been told by a few Yanmar folk, NOT worth the conversion costs. Plus, they say even if we did convert it, it the motor doesn't get hot enough to do any king of noticable heat transfer. We use the sun shower and the Zodi camp shower. It's combersome but it works. I ws just diddeling around w/ the idea of a 115 VAC generator on the motor.
The solution to this little problem will make someone wealthy. We have a 2GM. It's raw water cooled. It's 30+ years old and I have been told by a few Yanmar folk, NOT worth the conversion costs. Plus, they say even if we did convert it, it the motor doesn't get hot enough to do any king of noticable heat transfer. We use the sun shower and the Zodi camp shower. It's combersome but it works. I ws just diddeling around w/ the idea of a 115 VAC generator on the motor.
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