Why it's so hard to run a diesel properly.
- Thread starter Roger Long
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Guessing, I would suspect that if your engine is too big for your boat that it would be better for the engine to go ahead and increase the throttle even though you are throwing away money on extra fuel. All sailors are good at throwing away their mone anyway
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bad guess.Guessing, I would suspect that if your engine is too big for your boat that it would be better for the engine to go ahead and increase the throttle even though you are throwing away money on extra fuel. All sailors are good at throwing away their mone anyway
I have only 10hp but the hull is hard to push to a theoretical hull speed It is good to about 5.5 knots but above that I just dig a hole in the river. WLL is about 25 feet.
From page 37 of the pdf operating manual for Yanmar 9hp engines:
http://www.yanmarmarine.com/theme/y...peration manuals/1GM10_OM_ENGLISH_27Dec07.pdf
7. When operating the engine at low
speed for long periods of time, race the
engine once every two hours. Race the
engine with the clutch in NEUTRAL,
accelerate from the low speed position
to the high speed position and repeat
this process about five times. This
cleans out carbon from the cylinders
and the fuel injection valves.
Link:speed for long periods of time, race the
engine once every two hours. Race the
engine with the clutch in NEUTRAL,
accelerate from the low speed position
to the high speed position and repeat
this process about five times. This
cleans out carbon from the cylinders
and the fuel injection valves.
http://www.yanmarmarine.com/theme/y...peration manuals/1GM10_OM_ENGLISH_27Dec07.pdf
Very interesting. I can't think of any reason why it wouldn't apply to other small marine diesels. By "low power for long periods" I think they probably mean operations such as trolling while fishing. I believe, but would like more than anecdotal data, that operation in the 50-60% range only requires a period of higher power operation at similar intervals.
Our Hunter Vision has a 3JH2E engine. It will continue to accelerate up to the maximum RPM's.
I believe the chart that Roger presented. If you have the correct prop it will make a difference. We have had a couple of boats in our harbor that have had these issues. Once the switched props the boats did fine.
I believe the chart that Roger presented. If you have the correct prop it will make a difference. We have had a couple of boats in our harbor that have had these issues. Once the switched props the boats did fine.
Each hull shape has a different speed/power curve as you approach hull speed the curve gets very steep and at hull speed is nearly vertical.
Roger that was only for the small engine but Every heavy equipment operator I have ever known will pull the throttle wide open, if the engine has been idling for an extended period before he puts the machine to work.
Finally...
Why do truck drivers leave their engines idling??? One sees it all the time at highway truck stops.
A question I've been meaning to ask since I was four years old:
Why do truck drivers leave their engines idling??? One sees it all the time at highway truck stops.
Re: Finally...
It A: takes quite awhile to warm them up if they have sat in to cold all night B: they are driving the AC and or heater and C: it keeps the air tank full.. Before they put them on the road they shove the throttle wide open until the smoke clears. You can always tell when they are getting ready to hit the road. The trucks come alive with a roar and a cloud of black smoke.
It A: takes quite awhile to warm them up if they have sat in to cold all night B: they are driving the AC and or heater and C: it keeps the air tank full.. Before they put them on the road they shove the throttle wide open until the smoke clears. You can always tell when they are getting ready to hit the road. The trucks come alive with a roar and a cloud of black smoke.
Auxiliary heaters and power units are becoming increasingly popular in trucks, partly for the reasons we have been discussing here.
Except for hulls light enough and flat enough to get into semi-planing mode, the differences in the speed/power (or, more correctly, speed/resistance) curves will not be very significant. You are right however that the curve gets very steep at higher speeds for displacement hulls.
Don't they also use a small constant speed diesel for driving the refrigeration systems on the trailers?
Update November 7.
I just finished winterizing the boat and getting ready for haul out. One of my proactive maintenance projects for the winter is a new water cooled exhaust elbow on my 1979 Yanmar diesel. I got the hose pulled off and was able to stick my fingers up inside past the water inlet to where carbon would build up. Not only did it feel perfectly smooth, my finger came out absolutely clean, not even a smudge. Running your diesel in the proper RPM range and at WOT frequently for short periods really does make a difference.
I just finished winterizing the boat and getting ready for haul out. One of my proactive maintenance projects for the winter is a new water cooled exhaust elbow on my 1979 Yanmar diesel. I got the hose pulled off and was able to stick my fingers up inside past the water inlet to where carbon would build up. Not only did it feel perfectly smooth, my finger came out absolutely clean, not even a smudge. Running your diesel in the proper RPM range and at WOT frequently for short periods really does make a difference.
A timely article Richard
I just helped a friend move his Hunter 37 cutter from Winthrop to Marblehead to be hauled. He warmed the engine up at low RPM and then ran at no more than 2500 RPM all the way (wind was on our nose, so not much sailing), even after questioned it and discussed 80% of WOT with him. At the dock we revved it up and it seemed to run much smoother at 2700 rpm, but that was in neutral and therefore likely not representative.
I routinely operate my boat at 80% of WOT when under power and then also after coming into the harbor at lower rpm, just to keep it clean, based on the advice I have read on here. I know that the exhaust elbow should be a routine maintenance item, but my boat continues to run well, with no loss of max rpm, so I pretty much assume the elbow is okay. I also inspect my water pump annually and replace the impeller every other year. One thing I caught this year was that the bronze intake screen was quite fouled. I cleaned it out well. I also put some 5% muriatic acid through the engine (raw water cooled with no sea strainer), let it sit five minutes then flushed it out thoroughly.
I just helped a friend move his Hunter 37 cutter from Winthrop to Marblehead to be hauled. He warmed the engine up at low RPM and then ran at no more than 2500 RPM all the way (wind was on our nose, so not much sailing), even after questioned it and discussed 80% of WOT with him. At the dock we revved it up and it seemed to run much smoother at 2700 rpm, but that was in neutral and therefore likely not representative.
I routinely operate my boat at 80% of WOT when under power and then also after coming into the harbor at lower rpm, just to keep it clean, based on the advice I have read on here. I know that the exhaust elbow should be a routine maintenance item, but my boat continues to run well, with no loss of max rpm, so I pretty much assume the elbow is okay. I also inspect my water pump annually and replace the impeller every other year. One thing I caught this year was that the bronze intake screen was quite fouled. I cleaned it out well. I also put some 5% muriatic acid through the engine (raw water cooled with no sea strainer), let it sit five minutes then flushed it out thoroughly.
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