Has anyone figure out how many gallons per hour they burn with a 3 cyl yanmar 22hp engine. I have no fuel gauge. Anyone ever install one?? Where did you put it? How did you do it?
fuel question
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Most engines of that size use about
1/2 gph. If you have an hour meter, use it instead of doing all the work to put a fuel gage in. Hmmmmmmmmmm, an hour meter is a lot easier to add than a fuel gage and tank sender.
1/2 gph. If you have an hour meter, use it instead of doing all the work to put a fuel gage in. Hmmmmmmmmmm, an hour meter is a lot easier to add than a fuel gage and tank sender.
YANMAR ONE CYLINDER
I have a yanmar YSB 12 single cylinder pushing a catalina 30. I get about 1/2 gal per hour at 6 knots in a 12knot breeze heading into the wind.
I have a yanmar YSB 12 single cylinder pushing a catalina 30. I get about 1/2 gal per hour at 6 knots in a 12knot breeze heading into the wind.
Yes, if you dont have a fuel gauge don't bother
installing one as they are not that reliable. The best way is to know your burn rate and keep track of the hours used. Like Stu advises install an hour meter rather than a fuel gauge and sender. Besides the hour meter can advise you when is time to change oil and filters, adjust valves and other scheduled engine maintenance chores. Our boat has both and I use the hour meter regularly but the fuel gauge I just tap with my finger to see which way is going to go.
installing one as they are not that reliable. The best way is to know your burn rate and keep track of the hours used. Like Stu advises install an hour meter rather than a fuel gauge and sender. Besides the hour meter can advise you when is time to change oil and filters, adjust valves and other scheduled engine maintenance chores. Our boat has both and I use the hour meter regularly but the fuel gauge I just tap with my finger to see which way is going to go.
Burn Rate is Variable
Since a diesel trys to maintain constant rpms using a governor the fuel burn rate varies...sometimes a lot at the same rpms. I was used to my normal burn rate so wasn't watching my fuel gauge very closely. We had to motor into a strong wind all day to get across the bottom of Mobile bay. I "knew" my burn rate and was unconcerned. Well finally I decided to check for no good reason and was shocked. The gauge read below empty!!!! Fortunately we were near Bear Point Marina and we immediataely went in for fuel. Motoring into a strong wind apparently almost doubled my burn rate. A fuel gauge provides useful information. Also a fuel gauge allows you to keepthe tank about 1/4 full that way you don't have to carry around alot of extra fuel. I keep my tank about 1/4 full unless taking a longer trip. That way my fuel is fresher less chance for bugs to grow. Even at 1/4 I buy fuelonly once or twice a year. 5 gallons is at least 10 hours at normal burn rate. Considering that I usually motor less than an hour/trip to boat and go to boat 2 times/month 5 gallons is good for several months.
Since a diesel trys to maintain constant rpms using a governor the fuel burn rate varies...sometimes a lot at the same rpms. I was used to my normal burn rate so wasn't watching my fuel gauge very closely. We had to motor into a strong wind all day to get across the bottom of Mobile bay. I "knew" my burn rate and was unconcerned. Well finally I decided to check for no good reason and was shocked. The gauge read below empty!!!! Fortunately we were near Bear Point Marina and we immediataely went in for fuel. Motoring into a strong wind apparently almost doubled my burn rate. A fuel gauge provides useful information. Also a fuel gauge allows you to keepthe tank about 1/4 full that way you don't have to carry around alot of extra fuel. I keep my tank about 1/4 full unless taking a longer trip. That way my fuel is fresher less chance for bugs to grow. Even at 1/4 I buy fuelonly once or twice a year. 5 gallons is at least 10 hours at normal burn rate. Considering that I usually motor less than an hour/trip to boat and go to boat 2 times/month 5 gallons is good for several months.
Most diesel engines consume about 285 grams
of fuel per horse power hour. Motoring at slow speed in calm water uses the least horsepower so that your total consumption per hour will be low. Trying to run fast into a strong head wind will require more horsepower and will increase you fuel consumption per hour.
of fuel per horse power hour. Motoring at slow speed in calm water uses the least horsepower so that your total consumption per hour will be low. Trying to run fast into a strong head wind will require more horsepower and will increase you fuel consumption per hour.
Now Ross
If you are going to get scientific we need to know the definition of horsepower and also how to convert grams or diesel into liters or better yet gallons. Also go into how rpms and torgue relate to horsepower....don't forget that under load the propwill slip more and be less efficent....maybe we need a coefficent here.
If you are going to get scientific we need to know the definition of horsepower and also how to convert grams or diesel into liters or better yet gallons. Also go into how rpms and torgue relate to horsepower....don't forget that under load the propwill slip more and be less efficent....maybe we need a coefficent here.
Nice try Ross!
Okay... there are 454 grams in a pound. A gallon of diesel weighs about 7 lbs (plus or minus). I have a 30 hp diesel. According to Ross (285 grams times 30) I would burn 8550 grams per hour. 8550 divided by 454 equals 18.83 lbs. 18.83 lbs divided by 7 (lbs per gallon) equals 2.69 gallons. That is actually 5 times what my 30 hp diesel burns turning at 3000 rpm (boat doing 7.5 knots). I usually run at 2600 rpm and make 6 knots and burn .4 gallons per hour. I think that ross needs to have a mechanic take a look at his engine. There may be a problem with it.
Okay... there are 454 grams in a pound. A gallon of diesel weighs about 7 lbs (plus or minus). I have a 30 hp diesel. According to Ross (285 grams times 30) I would burn 8550 grams per hour. 8550 divided by 454 equals 18.83 lbs. 18.83 lbs divided by 7 (lbs per gallon) equals 2.69 gallons. That is actually 5 times what my 30 hp diesel burns turning at 3000 rpm (boat doing 7.5 knots). I usually run at 2600 rpm and make 6 knots and burn .4 gallons per hour. I think that ross needs to have a mechanic take a look at his engine. There may be a problem with it.
Liam it is not the rated HP of your engine that
counts it is the horse power absorbed by your propeller. probably you are not using anywhere near the horse power that you have available. If you propeller is matched to the weight of your boat and to your reduction gear then you can turn the engine at 2600 rpm and still not be absorbing your rated hp. I may be mistaken in using grams of fuel per hp/hour it may be .285 pounds/ hp/hour. That would make your power needs calculate to about 9-10 hp. If you were to try towing another boat into a strong head wind you would find that your engine was able but it would burn a lot more fuel.
counts it is the horse power absorbed by your propeller. probably you are not using anywhere near the horse power that you have available. If you propeller is matched to the weight of your boat and to your reduction gear then you can turn the engine at 2600 rpm and still not be absorbing your rated hp. I may be mistaken in using grams of fuel per hp/hour it may be .285 pounds/ hp/hour. That would make your power needs calculate to about 9-10 hp. If you were to try towing another boat into a strong head wind you would find that your engine was able but it would burn a lot more fuel.
There is a small difference between manufacturers
There is a small difference between manufacturers of engines but it ranges from .43 to .6 pounds per horsepower per hour. For instance my "20" horsepower BD772 by Beta Marine uses around .43 pounds per hour per horsepower so at 2,800 I would use 17 horsepower X .43 pounds or 7.3 pounds of diesel per hour. At 3,200 my consumption would be 19 horsepower X .43 or about 8.2 pounds per hour. If diesel weighs 7 pounds a gallon then this works out to around 1 gallon or 1.2 gallons per hour at each speed. All the best, Robert Gainer
There is a small difference between manufacturers of engines but it ranges from .43 to .6 pounds per horsepower per hour. For instance my "20" horsepower BD772 by Beta Marine uses around .43 pounds per hour per horsepower so at 2,800 I would use 17 horsepower X .43 pounds or 7.3 pounds of diesel per hour. At 3,200 my consumption would be 19 horsepower X .43 or about 8.2 pounds per hour. If diesel weighs 7 pounds a gallon then this works out to around 1 gallon or 1.2 gallons per hour at each speed. All the best, Robert Gainer
Moonsailor, The definition of horsepower
is easy, 33000 foot pounds of work per minute. Torque is measured in foot pounds. Therefore horse power is rpm times torque divided by 33000. Engine efficiency is measured by determineing the btu's in one hp and the btu's in a unit of fuel then you divide the btu value of the fuel per unit by the number of units used and the result is the measure of thermal efficiency for the engine.
is easy, 33000 foot pounds of work per minute. Torque is measured in foot pounds. Therefore horse power is rpm times torque divided by 33000. Engine efficiency is measured by determineing the btu's in one hp and the btu's in a unit of fuel then you divide the btu value of the fuel per unit by the number of units used and the result is the measure of thermal efficiency for the engine.
Torque the critical varible??
So with diesel torque is the critical varible determining GPH??? All RPM's are not equal!!! At 2000 rpm my diesel's govenor adjust fuel rate to acheive the desired rpms at constant rpms more torque equals more hp. Ignoring prop slip at a given rpm I should have a given speed. With a 20 kt wind going downwind less torque less fuel going upwind more torque more fuel. Dirt bottom more torque going into a current no effect (ignoring the effect of air drag). anyway my point is that if you are assuming a that a diesel burns fuel at a constant rate for a given RPM you might get in trouble. For planning purposes I assume a burn rate of 1/2 gallon/hr. This is conservative but I would rather arrive with fuel in the tank than run out of fuel. I have a 32' boat with a 22hp volvo MD11C.
So with diesel torque is the critical varible determining GPH??? All RPM's are not equal!!! At 2000 rpm my diesel's govenor adjust fuel rate to acheive the desired rpms at constant rpms more torque equals more hp. Ignoring prop slip at a given rpm I should have a given speed. With a 20 kt wind going downwind less torque less fuel going upwind more torque more fuel. Dirt bottom more torque going into a current no effect (ignoring the effect of air drag). anyway my point is that if you are assuming a that a diesel burns fuel at a constant rate for a given RPM you might get in trouble. For planning purposes I assume a burn rate of 1/2 gallon/hr. This is conservative but I would rather arrive with fuel in the tank than run out of fuel. I have a 32' boat with a 22hp volvo MD11C.
You've got it! hoist the sails and your engine
shares the work with the sails so you use less fuel. Sail at 5kts and know how much hp it takes to motor that fast and you know how much power you are getting from the wind.
shares the work with the sails so you use less fuel. Sail at 5kts and know how much hp it takes to motor that fast and you know how much power you are getting from the wind.
B737, I have been recording engine hours and fuel
consumption on my H34 for the past ten years plus. The overall average is about 3 hours/gallon for the 20 hp engine. That includes a lot of slow speed going in and out of the slip, and I only cruise at about 2300 rpm, so I would agree with MoonSailer's suggestion of 2 gallons/hour for conservative planning purposes. Noel Hasty s/v Principal Pleasure, Havre de Grace
consumption on my H34 for the past ten years plus. The overall average is about 3 hours/gallon for the 20 hp engine. That includes a lot of slow speed going in and out of the slip, and I only cruise at about 2300 rpm, so I would agree with MoonSailer's suggestion of 2 gallons/hour for conservative planning purposes. Noel Hasty s/v Principal Pleasure, Havre de Grace
I checked several diesel engine makers
fuel consumption rates and my error seems to have been substituting grams for milliliters. Fuel consumption rates of about .28 liters per hp/hour are pretty dependable. So if you are using less fuel than the arithmatic would suggest you probably don't use as much power as you have been thinking.
fuel consumption rates and my error seems to have been substituting grams for milliliters. Fuel consumption rates of about .28 liters per hp/hour are pretty dependable. So if you are using less fuel than the arithmatic would suggest you probably don't use as much power as you have been thinking.
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