Am purchasing a new H420 from Norton Marine in Deltaville, Va. Wanted to put on an Autoprop, but was told by dealer that Yanmar does not recommend the use of a feathering prop, and that doing so may void warranty on engine and transmission. Would someone from Yanmar confirm this and explain why this is policy. Would anyone from Maxprop and/or Autoprop like to comment. Anyone else have any comments???
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Gene Foraker
Check the warantee yourself
Sounds like BS. I'd check the warantee myself. I've never heard any anything like this. Did they say why?
Sounds like BS. I'd check the warantee myself. I've never heard any anything like this. Did they say why?
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bill walton
yanmar and feathreing prop
I talked with the factory auth yanmar technician in Marathon, FL last week about a similar subject. While scheduling regular service, alignment, etc., the subject of props came up. He asked what the maximum rpm I could pull with my 3 blade fixed prop, explaining that at full throttle, it should pull 3600-3700. I told him that I was planning a feathering prop and he told me that yanmar did not recommend a self-pitching prop, like the autoprop, but that a feathering prop like the max-prop is perfectly acceptable. BTW, the rpm number has to do with internal cylinder pressure under load.
I talked with the factory auth yanmar technician in Marathon, FL last week about a similar subject. While scheduling regular service, alignment, etc., the subject of props came up. He asked what the maximum rpm I could pull with my 3 blade fixed prop, explaining that at full throttle, it should pull 3600-3700. I told him that I was planning a feathering prop and he told me that yanmar did not recommend a self-pitching prop, like the autoprop, but that a feathering prop like the max-prop is perfectly acceptable. BTW, the rpm number has to do with internal cylinder pressure under load.
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Bob Knott
check the archives
Check the archives for my rantings about autoprop when i was commisioning my H380 last year. Love the prop, didn't work on my obat though. It's beautiful, expensive and hit my strut...nough said. Bob Knott h380
Check the archives for my rantings about autoprop when i was commisioning my H380 last year. Love the prop, didn't work on my obat though. It's beautiful, expensive and hit my strut...nough said. Bob Knott h380
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Charles Wolfe
Feathering and AutoProp
I cannot imagine why Yanmar would cast some doubts about the Autoprop. It may be because you have to make sure that you don't overload your engine when using it. Once you get to a certain point, giving more throttle only overloads the engine. But you will know it because you'll see the black smoke from the unburnt fuel.
I cannot imagine why Yanmar would cast some doubts about the Autoprop. It may be because you have to make sure that you don't overload your engine when using it. Once you get to a certain point, giving more throttle only overloads the engine. But you will know it because you'll see the black smoke from the unburnt fuel.
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Kevin L. Woody
Max-Prop Autoprop.
Dear Mr. Harrison: Thank you for your letter. Your letter brings to light two topics of concern by the engine manufactures. In the last few years the most vocal about these items has been Yanmar possibly because they may have the greatest percentage of the sailboat engine population out there. One of the greatest concerns they have, outside the normal engine maintenance, is the overloading of their engine’s. Overloading takes place at the point the engine is no longer capable of handling the amount of external load we place on the unit. This load is often check and rechecked by throttling the engine to maximum. If the engine is capable of obtaining maximum rpm’s you can assume external load being placed on the engine by outside items is correct. If the rpm’s achievable are greater then the max rated rpm’s the load is to small. If the rpm’s fall short of max rated there is too much load. Yanmar’s comments to you about overloading take place with a multitude of items. Some of the most common are high output alternators, addition engine pulley driven components, large towed dingy, excessive weight and most common propeller loads. With most conventional propellers the pitch, diameter or combination of the two can be altered in order to optimize the load to the engine allow it to obtain its rated maximum output. This maximum output capability ensures the user that the rpm, which the engine is running at, is being introduced with the optimum amount of designed fuel. When engine is overloaded the rpm’s are forced lower while using the high rpm’s fuel flow rate. This increase of additional fuel cannot be efficiently burnt causing carbon. This carbon is often seen as smoke either following the boat or witnessed on the transom. This smoke/carbon is what Yanmar has a great deal of problem’s with. It will cause a multitude of internal problems to the workings of the engine. I have heard Tec’s speak of cutting the life of an engine by half in severe overloading states. The Yanmar Tec in FL brought up Autoprop because it will not allow the engine to obtain the max rated rpm’s. The reason is that the Autoprop is continually seeking addition pitch depending on the pressures being placed on both sides of the blades. The faster the rotational speed the greater the pitch. The greater the pitch the greater the load. By their design self-pitching propellers do not have the ability of reducing its loads. Because of this it is very difficult to control their overloading characteristics. With other styles of feathering and fixed propellers simply re-pitching the propeller can eliminate the overload. The second concern by Yanmar is the shock load issue to the transmissions. A shock is produced anytime a transmission is placed into gear. In sever shifting patterns the transmission can actually be destroyed. Striking an object with the propeller during use can also causes a momentary stop to the transmission causing transmission failure. A poorly maintained folding or feathering propeller can cause shock load by opening only after addition rpm’s are used to force the blades out to there drive positions. As with any mechanical device it is best used far below it’s rated capacity’s. Hope this helps you. Sincerely, Kevin L. Woody
Dear Mr. Harrison: Thank you for your letter. Your letter brings to light two topics of concern by the engine manufactures. In the last few years the most vocal about these items has been Yanmar possibly because they may have the greatest percentage of the sailboat engine population out there. One of the greatest concerns they have, outside the normal engine maintenance, is the overloading of their engine’s. Overloading takes place at the point the engine is no longer capable of handling the amount of external load we place on the unit. This load is often check and rechecked by throttling the engine to maximum. If the engine is capable of obtaining maximum rpm’s you can assume external load being placed on the engine by outside items is correct. If the rpm’s achievable are greater then the max rated rpm’s the load is to small. If the rpm’s fall short of max rated there is too much load. Yanmar’s comments to you about overloading take place with a multitude of items. Some of the most common are high output alternators, addition engine pulley driven components, large towed dingy, excessive weight and most common propeller loads. With most conventional propellers the pitch, diameter or combination of the two can be altered in order to optimize the load to the engine allow it to obtain its rated maximum output. This maximum output capability ensures the user that the rpm, which the engine is running at, is being introduced with the optimum amount of designed fuel. When engine is overloaded the rpm’s are forced lower while using the high rpm’s fuel flow rate. This increase of additional fuel cannot be efficiently burnt causing carbon. This carbon is often seen as smoke either following the boat or witnessed on the transom. This smoke/carbon is what Yanmar has a great deal of problem’s with. It will cause a multitude of internal problems to the workings of the engine. I have heard Tec’s speak of cutting the life of an engine by half in severe overloading states. The Yanmar Tec in FL brought up Autoprop because it will not allow the engine to obtain the max rated rpm’s. The reason is that the Autoprop is continually seeking addition pitch depending on the pressures being placed on both sides of the blades. The faster the rotational speed the greater the pitch. The greater the pitch the greater the load. By their design self-pitching propellers do not have the ability of reducing its loads. Because of this it is very difficult to control their overloading characteristics. With other styles of feathering and fixed propellers simply re-pitching the propeller can eliminate the overload. The second concern by Yanmar is the shock load issue to the transmissions. A shock is produced anytime a transmission is placed into gear. In sever shifting patterns the transmission can actually be destroyed. Striking an object with the propeller during use can also causes a momentary stop to the transmission causing transmission failure. A poorly maintained folding or feathering propeller can cause shock load by opening only after addition rpm’s are used to force the blades out to there drive positions. As with any mechanical device it is best used far below it’s rated capacity’s. Hope this helps you. Sincerely, Kevin L. Woody
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Bryce Grefe
auto prop
I have an 18 inch autoprop on my H410, which I beleive is the same hull as the 420. My autoprop dealer took the time to test the loading of the Yanmar prior to signing off. I think the prop is great. Has eliminated all the problems of a tradional prop, i.e. not backing and the like, has imporved fuel efficiency and has higher speed in all types of wind and water conditons. So my read is that if its properly sized, and a little common sense is used you should have no problems with it. Bryce S/V Spellbinder
I have an 18 inch autoprop on my H410, which I beleive is the same hull as the 420. My autoprop dealer took the time to test the loading of the Yanmar prior to signing off. I think the prop is great. Has eliminated all the problems of a tradional prop, i.e. not backing and the like, has imporved fuel efficiency and has higher speed in all types of wind and water conditons. So my read is that if its properly sized, and a little common sense is used you should have no problems with it. Bryce S/V Spellbinder
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