My 1999 C-380, with a Westerbeke 42B and 3 blade prop, shakes at low rpms. (1500-1800).The stuffing box was also sprying water even after repeated adjustments. This winter I had a local mechanic check out the prop(balanced & tuned) and running gear. I also had the mechanic install a Federal flexible coupling for protection. I also wanted a PSS but the mechanic recommended trying the no drip seal. The first time I took the boat out this season, it still shakes at low RPMs but now I have a hum or whirling noise at the same RPM. Aso the packing nut came completely off allowing a "good stream" of water into the boat. What was frustrating is that I could not get the nut back on. I had to get another mechanic to help in an emergency. He had to pull real hard on the shaft to get the nut back on. I had the original mechanic realign the engine and repack the box. (At least he says he did). I am still shaking and whirling. I would love to get a PSS but I am afraid that something is wrong with my drive train and the PSS would not work. I can hand turn the shaft. This winter I also installed two shaft zincs and painted the prop, strut and shaft. Can you make any recommendations. Thanks
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Gary Jensen
engine vibration/winning
Duane, I too have a 380. I just bought it in Daytona Beach and trucked it to Ca where I recommissioned it. The second time out there was a low R.P.M. shaking of the engine, with a winning noise. It happened at 1000 rpm's. I tightened the fan belt and it did the trick. I was really suprised how much the belt made it shake at that rpm...Try it and let me know your results. The belt should only move 1/2 inch at the most movable point..Gary sail1752@aol.com
Duane, I too have a 380. I just bought it in Daytona Beach and trucked it to Ca where I recommissioned it. The second time out there was a low R.P.M. shaking of the engine, with a winning noise. It happened at 1000 rpm's. I tightened the fan belt and it did the trick. I was really suprised how much the belt made it shake at that rpm...Try it and let me know your results. The belt should only move 1/2 inch at the most movable point..Gary sail1752@aol.com
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Duane Maher
Thanks Gary
Gary, Thanks for your suggestion. Although the noise (more of a whirling type than whining) seems to come from the shaft area, your idea maybe a good one because I added a new alternator with a new fan belt. You know how new belts stretch and should be checked after initial use. I will check it out and let you know. Also the shaking can be felt at the helm. Thanks again. Duane
Gary, Thanks for your suggestion. Although the noise (more of a whirling type than whining) seems to come from the shaft area, your idea maybe a good one because I added a new alternator with a new fan belt. You know how new belts stretch and should be checked after initial use. I will check it out and let you know. Also the shaking can be felt at the helm. Thanks again. Duane
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Kevin L. Woody
Noise in shaft / my long winded response
Dear Duane Maher: The problem with chasing down vibrations is just that. We, you, can spend a great deal of time money and components to finally chase down an item or two which is your cause. Your letter includes a great deal of information, which leads me to think in two directions. The first is the whining noise at low rpm’s. You may want to break down the running gear into segments and try to inspect each of them. If the whining is not present when the engine is at idle we might rule out the engine. When we place the transmission into gear I assume that you do not hear the whining at idle. If the noise is only present at mid range of rpm’s we may start to rule out the stuffing box creating the noise. If the stuffing box was binding and creating noise I do not believe it could be selective with regards to rpm’s. If the propeller was out of balance or was damaged it would create noise through the whole range of rpm’s and not be selective. This does not mean that it may not have been necessary for the propeller to go through some kind of reconditioning or the shaft or stuffing box to be looked at. What you are describing may be related to the connection point between the transmission and the flywheel of the engine. Placed in between the two is a device called a damper plate. This damper plate allows a slight flexing to take place between the two main hard components of the flywheel and the transmission’s spline and gears. It is often found that when an engine is used in it’s mid range rpm’s, a back lash takes place between the transmission and the fly wheel. Literally what takes place is the propeller, shaft and transmission begin to overcome the flywheel’s rotation causing the damper plate to compress its springs. This compression is often described as a whining and clunking noise. Very visible throughout the drive train, and its components, as movement in these parts. Most stock damper plates have capability of deflection, or compression, of less then 3 degrees. There are some units out in the market, which sustain 33+ percent of deflection. You may find that giving the damper more freedom of movement may stop the whine. What you are describing is a very common occurrence in the industrial field of boating. ( Tugs, fish boats…) Most work boats utilize an high performance damper to stop what you are describing. Your stuffing box problems may simply be that you have tightened the unit to tight causing it to unscrew itself off the threaded housing. I would not feel that what you are describing is an unrepairable or unfixable state. The fact that the boat yard person had to force the shaft over to allow you to place the nut on would indicate that the shaft is obviously not running true through the stern tube. This is causing the stuffing box to force the shaft to one side making the stuffing box supportive. This is not a good situation for the packing. It will become very hot causing premature failure of it and possible scoring to the shaft. I would also check to make sure the shaft is not coming in contact with the stern tube wall. None of these item’s I have described would limit your use of a shaft seal. I hope this helps to shed some light. If you would like to follow up on this with me please feel free to contact me directly. Sincerely, Kevin L. Woody 800-523-7558 kwoody@pyiinc.com
Dear Duane Maher: The problem with chasing down vibrations is just that. We, you, can spend a great deal of time money and components to finally chase down an item or two which is your cause. Your letter includes a great deal of information, which leads me to think in two directions. The first is the whining noise at low rpm’s. You may want to break down the running gear into segments and try to inspect each of them. If the whining is not present when the engine is at idle we might rule out the engine. When we place the transmission into gear I assume that you do not hear the whining at idle. If the noise is only present at mid range of rpm’s we may start to rule out the stuffing box creating the noise. If the stuffing box was binding and creating noise I do not believe it could be selective with regards to rpm’s. If the propeller was out of balance or was damaged it would create noise through the whole range of rpm’s and not be selective. This does not mean that it may not have been necessary for the propeller to go through some kind of reconditioning or the shaft or stuffing box to be looked at. What you are describing may be related to the connection point between the transmission and the flywheel of the engine. Placed in between the two is a device called a damper plate. This damper plate allows a slight flexing to take place between the two main hard components of the flywheel and the transmission’s spline and gears. It is often found that when an engine is used in it’s mid range rpm’s, a back lash takes place between the transmission and the fly wheel. Literally what takes place is the propeller, shaft and transmission begin to overcome the flywheel’s rotation causing the damper plate to compress its springs. This compression is often described as a whining and clunking noise. Very visible throughout the drive train, and its components, as movement in these parts. Most stock damper plates have capability of deflection, or compression, of less then 3 degrees. There are some units out in the market, which sustain 33+ percent of deflection. You may find that giving the damper more freedom of movement may stop the whine. What you are describing is a very common occurrence in the industrial field of boating. ( Tugs, fish boats…) Most work boats utilize an high performance damper to stop what you are describing. Your stuffing box problems may simply be that you have tightened the unit to tight causing it to unscrew itself off the threaded housing. I would not feel that what you are describing is an unrepairable or unfixable state. The fact that the boat yard person had to force the shaft over to allow you to place the nut on would indicate that the shaft is obviously not running true through the stern tube. This is causing the stuffing box to force the shaft to one side making the stuffing box supportive. This is not a good situation for the packing. It will become very hot causing premature failure of it and possible scoring to the shaft. I would also check to make sure the shaft is not coming in contact with the stern tube wall. None of these item’s I have described would limit your use of a shaft seal. I hope this helps to shed some light. If you would like to follow up on this with me please feel free to contact me directly. Sincerely, Kevin L. Woody 800-523-7558 kwoody@pyiinc.com
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terry dornan
zincs ?
Rotational inertia is independent of the mass distribution - however harmonic imbalance is not. It is a function of angular velocity. In short, I would consider the size and location of any weight placed on a shaft. Shaft zincs are molded to distribute a balanced load at the center of mass. This is a balance of the two different densities involved- the zinc and the fastener (connection bolt or cap screw). Proper alignment of two such dynamic systems on a shaft in a fashion that they would not cause a harmonic unbalance is very unlikely. So- Loose one Zinc.
Rotational inertia is independent of the mass distribution - however harmonic imbalance is not. It is a function of angular velocity. In short, I would consider the size and location of any weight placed on a shaft. Shaft zincs are molded to distribute a balanced load at the center of mass. This is a balance of the two different densities involved- the zinc and the fastener (connection bolt or cap screw). Proper alignment of two such dynamic systems on a shaft in a fashion that they would not cause a harmonic unbalance is very unlikely. So- Loose one Zinc.
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