When running under power at 3000 rpm the stern of the boat is pushed down. This allows exhaust residue to stain the stern of the boat as the exhaust seems to be sucked back onto the transome of the boat leaving a grey moustache on the stern of the boat. Any one have a fix for this problem. I have considered moving the exhaust thru-hull to an area on thee side of the boat 7 to 10 inches above the water line and a couple of inches ahead of the transome... Any thoughts?
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what i've heard...
Don't wax the stern of the boat. Try putting baby oil on the stained area in question. Seems to work fine.
Don't wax the stern of the boat. Try putting baby oil on the stained area in question. Seems to work fine.
What's the concern?
Are you concerned with the visual effects of the stain or the reason for the dirty exhaust? If the problem is the quality of the exhaust I would suggest that you may be causing the engine to work too hard creating an exhaust composed of un-burned fuel and no matter where you route the exhaust port you'll have the same problem. In other words, the stain may be the symptom of the problem. Check the exhaust emission at different RPM's at the dock under load (in gear) and see if you are blowing anything out. Look at the color and then look at the archives in this sight for some guidance. On the other hand, I know if I run under power for a couple of hours up the Patapsco River to Baltimore the fact is the transom squat will pick up some stains. That is caused by the vortex effect created by the vessel moving through the dirty water of that river (watch the water you'll see it flow backwards onto the transom). I would be very careful about any re-routing of the exhaust port for a couple of reasons. One of which is, if the exhaust water can not flow freely it will create back pressure in the engine with all of its attend problems. After a Baltimore trip I'll use acetone to clean any stains and then re-wax the area. Good luck Lee
Are you concerned with the visual effects of the stain or the reason for the dirty exhaust? If the problem is the quality of the exhaust I would suggest that you may be causing the engine to work too hard creating an exhaust composed of un-burned fuel and no matter where you route the exhaust port you'll have the same problem. In other words, the stain may be the symptom of the problem. Check the exhaust emission at different RPM's at the dock under load (in gear) and see if you are blowing anything out. Look at the color and then look at the archives in this sight for some guidance. On the other hand, I know if I run under power for a couple of hours up the Patapsco River to Baltimore the fact is the transom squat will pick up some stains. That is caused by the vortex effect created by the vessel moving through the dirty water of that river (watch the water you'll see it flow backwards onto the transom). I would be very careful about any re-routing of the exhaust port for a couple of reasons. One of which is, if the exhaust water can not flow freely it will create back pressure in the engine with all of its attend problems. After a Baltimore trip I'll use acetone to clean any stains and then re-wax the area. Good luck Lee
Look For Root Cause
Agree with Lee - it would be better to look for the cause of the emission problem. If the engine is operating off from optimum fuel to air ratio this can cause a smokey exhaust. There are several reasons for this and I can list a few to give an idea: Mixing elbow: It may be your mixing elbow is starting to be too constricted. Does the engine seem like it has been running warmer than it used to? There should be more steam coming out than usual at regular cruise speed, 2850 rpm. Prop pitch: A prop change can cause smoking. I added a feathering prop and the pitch was off a notch and this caused smoking. After adjusting to the proper pitch the smoke problem all but disapeared. Other items such as dirty air cleaner, dirty fuel filters, etc can cause a change in the fuel/air mixture but not all changes, though, will cause black smoke.
Agree with Lee - it would be better to look for the cause of the emission problem. If the engine is operating off from optimum fuel to air ratio this can cause a smokey exhaust. There are several reasons for this and I can list a few to give an idea: Mixing elbow: It may be your mixing elbow is starting to be too constricted. Does the engine seem like it has been running warmer than it used to? There should be more steam coming out than usual at regular cruise speed, 2850 rpm. Prop pitch: A prop change can cause smoking. I added a feathering prop and the pitch was off a notch and this caused smoking. After adjusting to the proper pitch the smoke problem all but disapeared. Other items such as dirty air cleaner, dirty fuel filters, etc can cause a change in the fuel/air mixture but not all changes, though, will cause black smoke.
There is always a little soot in the exhaust water
it's just a by product of burning diesel fuel. Granted, over working an engine will cause MORE soot than normal. The exhaust water mixes with the smoke and after a period of time and the vortex of water around the transom under way leaves black stains. Just wash them off using boat soap or something a little stronger like "Krazy Klean"
it's just a by product of burning diesel fuel. Granted, over working an engine will cause MORE soot than normal. The exhaust water mixes with the smoke and after a period of time and the vortex of water around the transom under way leaves black stains. Just wash them off using boat soap or something a little stronger like "Krazy Klean"
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