Taking a cruise & trying to cover all bases -- 12 gallon tank -- If I hadto power all the way, how far could I go? O'Day 27 2 blade prop -- Huill speed 6.7 -- engine cruises at 6 knots
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David
A-4
One of my previous boats had an Atomic 4 that got 1/2 gallon per hour. I would suggest you use your per hour consumption figure to determine your distance capability under power.
One of my previous boats had an Atomic 4 that got 1/2 gallon per hour. I would suggest you use your per hour consumption figure to determine your distance capability under power.
Lot of factors.
Mike: When you are trying to determine fuel consumption there are many things to consider. Prop and bottom condition are probably the two most crucial factors. A dirty prop and bottom can increase the fuel consumption dramatically. The other thing is you never want to get too low on fuel (water and garbage in the bottom of the tank), so plan on 9-10 gals of usage in the tank (not 12).
Mike: When you are trying to determine fuel consumption there are many things to consider. Prop and bottom condition are probably the two most crucial factors. A dirty prop and bottom can increase the fuel consumption dramatically. The other thing is you never want to get too low on fuel (water and garbage in the bottom of the tank), so plan on 9-10 gals of usage in the tank (not 12).
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Bob Howie
Fuel Consumption
I think the comment that an A4 uses about a half-gallon per hour fuel burn is a little optimistic because I've had a few of those and they burned more than than, more like 2-3 gallons per hour on a fairly clean bottom. The half-gallon per hour observation is a little generous, too, in my opinion, because my 24hp diesel only burns about 3/4 gal. per hour and diesel is always more efficient and burns much less fuel than gasoline engines. Don Moyer is the guru of the A4 and you can check his website, www.moyermarine.com, for the real skinny on the A4.
I think the comment that an A4 uses about a half-gallon per hour fuel burn is a little optimistic because I've had a few of those and they burned more than than, more like 2-3 gallons per hour on a fairly clean bottom. The half-gallon per hour observation is a little generous, too, in my opinion, because my 24hp diesel only burns about 3/4 gal. per hour and diesel is always more efficient and burns much less fuel than gasoline engines. Don Moyer is the guru of the A4 and you can check his website, www.moyermarine.com, for the real skinny on the A4.
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David
A-4 fuel
Bob, you are right about Don Moyer being the A4 Guru. My Tartan 30 with the A4 did burn about 1/2 gallon per hour at 5 knots. I did'nt push it but what kind of boat did you have to get only 2-3 gallons per hour? Did you have the direct drive or 2:1 or different V drive? That is a lot of fuel for a great little gas engine.
Bob, you are right about Don Moyer being the A4 Guru. My Tartan 30 with the A4 did burn about 1/2 gallon per hour at 5 knots. I did'nt push it but what kind of boat did you have to get only 2-3 gallons per hour? Did you have the direct drive or 2:1 or different V drive? That is a lot of fuel for a great little gas engine.
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Bob Howie
Fading Memory
It's been about 8 or 9 years now since I last owned an A4 and, to be honest, I don't really remember what the fuel burn was, but it always seemed higher than a half-gallon per hour. Of course, I am glad to stand corrected because I am a great fan of the mightly little A4. I've had 3 boats with them and the first one, no one around knew anything about the engine. It was frozen up, so I finally got my hands on some books, yanked the motor out and tore it down before taking it over to the local NAPA machine shop where the head guy said, "Oh! An Atomic 4; haven't seen one of those since I was in the army." Apparently the army used them in jeeps or something. The guy really helped me out and it was a great engine the entire time I had it, but my recollection remains that it burned a fair amount of gas more than a half-gallon per hour. If that is correct, tho, then bully for the A4 going knot for knot and ounce for ounce up against the diesels. Personally, I think folks looking for a "first" boat and running on a budget shouldn't overlook those boats with A4's in them. When I was considering ways to repower my 78h30 about 18 months ago, I actually considering a retro-repower using an Moyer-rebuilt A4. I talked to Don about it and he's a helluva guy who will, it appears to me, do anything he can to help. He publishes a service manual on the A4 for $50 that anyone with an A4 should immediately buy. But, as I said, "first boat" owners shouldn't overlook the value of A4-powered boats. There's an Ericson 32 on the end of my pier that's in fair shape with an A4 and could be bought for a price advantageous to both buyer and seller, but I've actually heard the brokers nay-saying the boat because of the A4. Just goes to show that brokers sometimes don't know what they are talking about. So, here's to A4's! May they always find a good home!!
It's been about 8 or 9 years now since I last owned an A4 and, to be honest, I don't really remember what the fuel burn was, but it always seemed higher than a half-gallon per hour. Of course, I am glad to stand corrected because I am a great fan of the mightly little A4. I've had 3 boats with them and the first one, no one around knew anything about the engine. It was frozen up, so I finally got my hands on some books, yanked the motor out and tore it down before taking it over to the local NAPA machine shop where the head guy said, "Oh! An Atomic 4; haven't seen one of those since I was in the army." Apparently the army used them in jeeps or something. The guy really helped me out and it was a great engine the entire time I had it, but my recollection remains that it burned a fair amount of gas more than a half-gallon per hour. If that is correct, tho, then bully for the A4 going knot for knot and ounce for ounce up against the diesels. Personally, I think folks looking for a "first" boat and running on a budget shouldn't overlook those boats with A4's in them. When I was considering ways to repower my 78h30 about 18 months ago, I actually considering a retro-repower using an Moyer-rebuilt A4. I talked to Don about it and he's a helluva guy who will, it appears to me, do anything he can to help. He publishes a service manual on the A4 for $50 that anyone with an A4 should immediately buy. But, as I said, "first boat" owners shouldn't overlook the value of A4-powered boats. There's an Ericson 32 on the end of my pier that's in fair shape with an A4 and could be bought for a price advantageous to both buyer and seller, but I've actually heard the brokers nay-saying the boat because of the A4. Just goes to show that brokers sometimes don't know what they are talking about. So, here's to A4's! May they always find a good home!!
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Scott Narum
My A-4 Experience
I used to have a Catalina 30 with an A-4. I also used to burn 2-3 gallons per hour, and I rarely ran it full out. I'm sorry but I don't believe 1/2 gallons per hour with a flathead ancient engine like the A-4. While it did perform reasonably well, it had the following drawbacks: 1. fuel consumption that was much greater than a comparable diesel, 2. bizarre maintenance items like a "grease cup" on the water pump that you manually turned as grease was consumed, 3. fear of the combustibility of gasoline, 4. points and condenser (!), 5. the very real and significant negative effect the A-4 has on resale value. I have a Hunter 326 now with a 18 hp Yamar diesel, and it is great. And believe me, it uses less than half the fuel the A-4 did.
I used to have a Catalina 30 with an A-4. I also used to burn 2-3 gallons per hour, and I rarely ran it full out. I'm sorry but I don't believe 1/2 gallons per hour with a flathead ancient engine like the A-4. While it did perform reasonably well, it had the following drawbacks: 1. fuel consumption that was much greater than a comparable diesel, 2. bizarre maintenance items like a "grease cup" on the water pump that you manually turned as grease was consumed, 3. fear of the combustibility of gasoline, 4. points and condenser (!), 5. the very real and significant negative effect the A-4 has on resale value. I have a Hunter 326 now with a 18 hp Yamar diesel, and it is great. And believe me, it uses less than half the fuel the A-4 did.
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David
A-4 Milage
Scott you are right about the A-4 maintenance being a pain and the re sale problem also. My boat was 3000 lbs. lighter than the Catalina 30 and the engine was always babied. The A-4 was listed as 30 HP but actually only put out 15 HP at the prop. I too get better gallons per hour with a higher horsepower Yanmar and faster speed with a much heavier boat. However, 3 gallons per hour seems a bit much for that little engine.
Scott you are right about the A-4 maintenance being a pain and the re sale problem also. My boat was 3000 lbs. lighter than the Catalina 30 and the engine was always babied. The A-4 was listed as 30 HP but actually only put out 15 HP at the prop. I too get better gallons per hour with a higher horsepower Yanmar and faster speed with a much heavier boat. However, 3 gallons per hour seems a bit much for that little engine.
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Bob Howie
What Don Moyer says...
Ok..Don Moyer, we all admit, is pretty much the current guru of the A4, so I went to his website and here's a direct quote from his FAQs section..."Fuel consumption is about 3/4 gallons per hour. With an adjustable main jet, many folks lean their engines to as low as 1/2 gallon per hr." Be it far removed from me that I contradict what this man who makes his living building, rebuilding and modifying A4's says, but I went back to my notebook and I can promise you I never got this kind of fuel economy. The boat I had at the time was an Irwin 32 Citation, about 12,500 pounds of boat. Maybe there was something I wasn't doing right because I'll admit that at the time I knew neither Don Moyer nor anyone else who could tell me anything about the A4 or how to work on it, so I pretty much did it by reading a relatively uninspired maintenance book. It could have all been about me and what I was or was not doing. However, all this being said and acknowledging the fact that I am an A4 fan and like the little engine just fine, I can't believe it gets equal to or, maybe in some cases, better fuel economy than my 24hp Bukh diesel. And, like I have said repeatedly, I could well be wrong here. But, there's the quote from Don Moyer and I would expect the man knows what he's talking about.
Ok..Don Moyer, we all admit, is pretty much the current guru of the A4, so I went to his website and here's a direct quote from his FAQs section..."Fuel consumption is about 3/4 gallons per hour. With an adjustable main jet, many folks lean their engines to as low as 1/2 gallon per hr." Be it far removed from me that I contradict what this man who makes his living building, rebuilding and modifying A4's says, but I went back to my notebook and I can promise you I never got this kind of fuel economy. The boat I had at the time was an Irwin 32 Citation, about 12,500 pounds of boat. Maybe there was something I wasn't doing right because I'll admit that at the time I knew neither Don Moyer nor anyone else who could tell me anything about the A4 or how to work on it, so I pretty much did it by reading a relatively uninspired maintenance book. It could have all been about me and what I was or was not doing. However, all this being said and acknowledging the fact that I am an A4 fan and like the little engine just fine, I can't believe it gets equal to or, maybe in some cases, better fuel economy than my 24hp Bukh diesel. And, like I have said repeatedly, I could well be wrong here. But, there's the quote from Don Moyer and I would expect the man knows what he's talking about.
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Scott Narum
I stand by My Previous Post
I still say I experienced 2 to 3 gph. It was easy to gauge, because I put in 5 gallons from a portable container after every other sail...and I didn't motor all that much. Don't forget..the A-4 may be relatively small, but it IS four cylinders with a FLAT head...inefficient at best.
I still say I experienced 2 to 3 gph. It was easy to gauge, because I put in 5 gallons from a portable container after every other sail...and I didn't motor all that much. Don't forget..the A-4 may be relatively small, but it IS four cylinders with a FLAT head...inefficient at best.
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Rob Rich
Come On Guys... 2-3 Gallons? No Way...
I can tell you this. The only way that I can accurately guage fuel consumption on my C-27 (considering that the average fuel guage is extremely inaccruate)is to top off the tank, drive her for about 3-4 hours, and then top her off again. Repeatedly, I have recorded consumption rates between .75 gallons per hour and 1.25 gallons per hour. The mean (not the median, but the mean) fuel economy worked out to around 1.0 gallons per hour. In general, an A-4 in good shape should give you this score. If it does not, it probably means that one or more things is wrong with the engine. It could be something as simple as the mixture, or something as drastic as compression. The only way to find out for sure is to run a test on your engine. Top her off, run her under load for two hours, and top her off again. This will give you a ball park for your particular engine. Remeber that one of the worst things you can do to your A-4 is to let it sit. Many people report that they rarely, if ever, run their engine. This will do more damage than good to an A-4. In addtion, the A-4 is a gasoline engine, so factors such as points, wires, plugs, distributor caps, carburateur condition and fuel quality will factor greatly in your economy. Let us know how you fare.... and have fun doing it! Best Regards, Rob
I can tell you this. The only way that I can accurately guage fuel consumption on my C-27 (considering that the average fuel guage is extremely inaccruate)is to top off the tank, drive her for about 3-4 hours, and then top her off again. Repeatedly, I have recorded consumption rates between .75 gallons per hour and 1.25 gallons per hour. The mean (not the median, but the mean) fuel economy worked out to around 1.0 gallons per hour. In general, an A-4 in good shape should give you this score. If it does not, it probably means that one or more things is wrong with the engine. It could be something as simple as the mixture, or something as drastic as compression. The only way to find out for sure is to run a test on your engine. Top her off, run her under load for two hours, and top her off again. This will give you a ball park for your particular engine. Remeber that one of the worst things you can do to your A-4 is to let it sit. Many people report that they rarely, if ever, run their engine. This will do more damage than good to an A-4. In addtion, the A-4 is a gasoline engine, so factors such as points, wires, plugs, distributor caps, carburateur condition and fuel quality will factor greatly in your economy. Let us know how you fare.... and have fun doing it! Best Regards, Rob
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Garry
Gas Mileage
The problem with the A4 in relatively small sail boats like Cat 27s and 30s is that it is too powerful! It is possible to run the beast at full throttle and try to drive the hull well above hull speed but horsepower requirements increase as the cube of the speed. It costs 53% more gallons per hour to run a Cat 27 at 7.5 knots than it does at 6.5 knots. If you are using all of the horsepower available in these smaller (shorter waterline) hulls you will naturally use more fuel because you are using lots of horsepower beating the water to a froth for a very modest increase in speed. Actually, flat head engines are not particularly inefficient from a thermodynamic point of view but they have low power to weight ratios. Almost all internal combustion engines put about a third of their energy into useful work, a third into the cooling water and a third into the exhaust gas. Flat heads like the A4 just don't produce as much power per pound of cast iron but they are not significantly less efficient. There is a rule of thumb that says that gasoline engines should consume about one gallon of fuel per horsepower per day and diesels half as much. If your fuel utilization is very substantially above this then you probably have a problem with the power train, most likely an improperly pitched prop.
The problem with the A4 in relatively small sail boats like Cat 27s and 30s is that it is too powerful! It is possible to run the beast at full throttle and try to drive the hull well above hull speed but horsepower requirements increase as the cube of the speed. It costs 53% more gallons per hour to run a Cat 27 at 7.5 knots than it does at 6.5 knots. If you are using all of the horsepower available in these smaller (shorter waterline) hulls you will naturally use more fuel because you are using lots of horsepower beating the water to a froth for a very modest increase in speed. Actually, flat head engines are not particularly inefficient from a thermodynamic point of view but they have low power to weight ratios. Almost all internal combustion engines put about a third of their energy into useful work, a third into the cooling water and a third into the exhaust gas. Flat heads like the A4 just don't produce as much power per pound of cast iron but they are not significantly less efficient. There is a rule of thumb that says that gasoline engines should consume about one gallon of fuel per horsepower per day and diesels half as much. If your fuel utilization is very substantially above this then you probably have a problem with the power train, most likely an improperly pitched prop.
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Del Wiese
I agree with Don Moyer
I had a 1968 Cal 28 with Atomic 4 and 2 bladed fixed prop. Fuel consumption was 3/4 gal/hour. Don is indeed the guru of Atomic 4s, he helped me solve problems on several occassions, great guy!
I had a 1968 Cal 28 with Atomic 4 and 2 bladed fixed prop. Fuel consumption was 3/4 gal/hour. Don is indeed the guru of Atomic 4s, he helped me solve problems on several occassions, great guy!
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Bob Howie
Gary's point is taken
I think Gary's point is, in fact, on point. After a certain point, you just burn more gas without producing more headway and therein might lie some problem with the fuel burn. But, I do know what I do know and that is that even at theoretcal hull speed and without running the engine full-bore, I still didn't get the tea-sipping mileage some are claiming. I think, however, that if one were to follow Moyer's A4 manual and do the things he suggests, that the lessening fuel burn would approach the theoretical. I think all the points being made here, i.e., condition of engine, timing, carb et.al are all points well made.
I think Gary's point is, in fact, on point. After a certain point, you just burn more gas without producing more headway and therein might lie some problem with the fuel burn. But, I do know what I do know and that is that even at theoretcal hull speed and without running the engine full-bore, I still didn't get the tea-sipping mileage some are claiming. I think, however, that if one were to follow Moyer's A4 manual and do the things he suggests, that the lessening fuel burn would approach the theoretical. I think all the points being made here, i.e., condition of engine, timing, carb et.al are all points well made.
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Lori
1g/hr for my R-29
I got just under a gallon an hour with my Ranger 29 (6400 lb), 2-blade prop, cruising speed at 6.2k at 1800 rpm. Good luck!
I got just under a gallon an hour with my Ranger 29 (6400 lb), 2-blade prop, cruising speed at 6.2k at 1800 rpm. Good luck!
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