I have this engine on my H-27. I have experienced an ongoing issue with black (not blue) smoke when under power. This fouls the stern and has been the topic of discussion with several boaters that have seen it while we were out on the water. The injector was removed and rebuilt last fall, after several other things were checked out (mixing elbow, filters, fuel -old and new). Now, the mechanics and various individuals with some diesel knowledge seem to think that it is the prop. My original prop is a 13 x 10, right hand rotation with 1" bore. Questions: Anyone experienced this? Recondition the one that is on there (pull the boat, remove the prop, store the boat on the cradle, re-float the boat)? Buy a new prop for about 200 and have a diver remove and reinstall? If buy a new one, have the old one reconditioned for a back up at a cost of about $40? Any thoughts, ideas, suggestions are greatly appreciated. We are planning a trip in early July and will be out for about 7 days; if there is not wind, we could end up motoring for lots of miles. Either way, we do not want to damage a multi-thousand dollar engine for a few hundred dollar solution. BTW, IF we are going the new prop route, it needs to be ordered SOON. Again, thanks to everyone for your enlightenment. This forum is always full of good knowledge and ideas.
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You need a prop expert but....
Jay: You need a prop expert to tell you exactly which prop pitch/diameter is right for your boat. A couple of things you can check for your self. 1. Will your engine rev to 3600 (max rated RPM) in neutral? If it does not it should. 2. Will your engine rev to 3400-3600 in gear? If it does not it should but there are different reasons for this. Clean bottom, clean prop and the correct diameter/pitch. 3. Having everthing correct will help some of your black smoke problem. As you have been told, this is a sign of an overload. You should be running your engine around 2500-2900 rpms when cruising. I would have a diver pull your existing prop, take it to the prop shop and reinstall it on the boat. If you make an appointment with the prop shop, they should be able to turn it around the same day. If they only charge $40 to repitch it, it cannot take more than a hour or so. Why spend money on another prop that you will probably never use? To clean up the stern, get an Island Girl kit to clean, condition and seal the Gelcoat. It makes cleaning it much easier in the future. Even with a properly functioning Engine/Prop combination you are bound to get some soot and this will make it easier to clean up.
Jay: You need a prop expert to tell you exactly which prop pitch/diameter is right for your boat. A couple of things you can check for your self. 1. Will your engine rev to 3600 (max rated RPM) in neutral? If it does not it should. 2. Will your engine rev to 3400-3600 in gear? If it does not it should but there are different reasons for this. Clean bottom, clean prop and the correct diameter/pitch. 3. Having everthing correct will help some of your black smoke problem. As you have been told, this is a sign of an overload. You should be running your engine around 2500-2900 rpms when cruising. I would have a diver pull your existing prop, take it to the prop shop and reinstall it on the boat. If you make an appointment with the prop shop, they should be able to turn it around the same day. If they only charge $40 to repitch it, it cannot take more than a hour or so. Why spend money on another prop that you will probably never use? To clean up the stern, get an Island Girl kit to clean, condition and seal the Gelcoat. It makes cleaning it much easier in the future. Even with a properly functioning Engine/Prop combination you are bound to get some soot and this will make it easier to clean up.
D
Dick Litchfield
Switched to 3-blade!
The black smoke you are experiencing can be caused by overloading the engine. The overload is usually a fouled prop or a prop that is improperly sized to the engine/boat. We have a 81 H27. It had the little Yanmar and a 13x10 also. We experieced a minor amount of sooting and black smoke when we first got the boat. The smoke was never considered a problem as we were more concerned with vibration and a tight spot in the shaft rotation. We contacted the the folks at Wildcat Propellers. They checked the prop and shaft (for free)and found the prop was out of balance and the blades were not pitched the same (the vibration). The tight spot turned out to be a bent shaft. The big fix was a new shaft & half coupling and new 3-blade (12X7) sailor type Astral prop. Operation now is really smooth and the sooting and smoke problems have disappeared with these changes. The Astral delivery from Australia took a couple of weeks. The cost of putting my old two blade in first class condition pushed me toward the new prop. Talk to your prop shop or the folks at Wildcat. Wildcat also has a website.
The black smoke you are experiencing can be caused by overloading the engine. The overload is usually a fouled prop or a prop that is improperly sized to the engine/boat. We have a 81 H27. It had the little Yanmar and a 13x10 also. We experieced a minor amount of sooting and black smoke when we first got the boat. The smoke was never considered a problem as we were more concerned with vibration and a tight spot in the shaft rotation. We contacted the the folks at Wildcat Propellers. They checked the prop and shaft (for free)and found the prop was out of balance and the blades were not pitched the same (the vibration). The tight spot turned out to be a bent shaft. The big fix was a new shaft & half coupling and new 3-blade (12X7) sailor type Astral prop. Operation now is really smooth and the sooting and smoke problems have disappeared with these changes. The Astral delivery from Australia took a couple of weeks. The cost of putting my old two blade in first class condition pushed me toward the new prop. Talk to your prop shop or the folks at Wildcat. Wildcat also has a website.
J
Jay Kent
Dick, did the 3 blade achieve
the 3600 rpm, etc. that Steve wrote about? Those are the same numbers that my diesel mechanic is shooting to achieve with a new - or reconditioned two blade. Vibration is not a problem. Also, on the 12 x 7, where did you get the info that determined that it was okay for the Yanmar? Greg Emerson at Hunter sent me specs about the 13 x 10. Yanmar told me that only the boat manufacturer would be able to advise size and pitch due to the "load testing" that they perform. Thoughts? Thanks for the response.
the 3600 rpm, etc. that Steve wrote about? Those are the same numbers that my diesel mechanic is shooting to achieve with a new - or reconditioned two blade. Vibration is not a problem. Also, on the 12 x 7, where did you get the info that determined that it was okay for the Yanmar? Greg Emerson at Hunter sent me specs about the 13 x 10. Yanmar told me that only the boat manufacturer would be able to advise size and pitch due to the "load testing" that they perform. Thoughts? Thanks for the response.
I would not depend on Hunter.
Jay: I would not depend on Hunter for these calcs. My H'31 had a 15 x 12 (factory) and it was too much for the engine. We dropped down to a 15 x 11 and it is better, but 15 x 10 would probably be perfect. Let the prop guy calculate the perfect prop and let him be responsible for the removal and replacement. This way if he mis-calculates he can pay for the R/R until it is correct. Generally if you move from a two blade prop to a three you would knock 1-2 deg of pitch from the 3 blade (assuming the same diameter). Decreasing the diameter by one inch does approx. the same thing as removing 1 deg of pitch. These are rules of thumb and not from the bible!!!
Jay: I would not depend on Hunter for these calcs. My H'31 had a 15 x 12 (factory) and it was too much for the engine. We dropped down to a 15 x 11 and it is better, but 15 x 10 would probably be perfect. Let the prop guy calculate the perfect prop and let him be responsible for the removal and replacement. This way if he mis-calculates he can pay for the R/R until it is correct. Generally if you move from a two blade prop to a three you would knock 1-2 deg of pitch from the 3 blade (assuming the same diameter). Decreasing the diameter by one inch does approx. the same thing as removing 1 deg of pitch. These are rules of thumb and not from the bible!!!
J
Jay Kent
Steve, your thoughts are well made and
well taken! I am in touch with the prop guy now, and he is working out the numbers for 2 vs 3 and 13 x 10 to 12 x 7. Says it should work the same for the small diesel, but wants to check to be sure. I am now, checking with a diver who may want to do the change out at my slip for the cost of the air!! Sounds interesting, and worth (read that: dollars saved) the time. Thanks.
well taken! I am in touch with the prop guy now, and he is working out the numbers for 2 vs 3 and 13 x 10 to 12 x 7. Says it should work the same for the small diesel, but wants to check to be sure. I am now, checking with a diver who may want to do the change out at my slip for the cost of the air!! Sounds interesting, and worth (read that: dollars saved) the time. Thanks.
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