Drive Line Noise

[Russ Smith]

HiI've got a 79 model Catalina 30, with a 27 horse Yanmar Diesel. I seem to have a noise in the drive shaft....almost sounds like a bearing noise, but I'm not certain about that....its a bit of a squeak that changes with RPM. Anyone have any ideas about what it could be....and how to correct it?Thanks Russ

 

[Steve Linsk]

Noise at Different RPMs

My two cents from sitting through one too many mechanical engineering classes...Noise that appears only at certain RPMs results when the frequency of vibration of the prop shaft assemby matches the natural frequency of other structural parts of the boat. This is a lot of gobblety gook for saying you probably need to 1) have an engine mechanic realign the engine with the prop shaft by properly adjusting the engine mounting bolts or 2)the bearing in the prop shaft strut on the underside of your hull needs to be replaced. I would start with 1) and see if this fixes the problem since 2)requires a haul-out and will be more expensive. There may also be a a problem with the stuffing box where the prop exits the hull. Again, a mechanic should be able to verify or fix this.Good luck!

 

[Ron]

Me too!

My 82 Cat 30 makes the same kinda sound. At low RPM's it sounds squeaky, like a bearing is failing. My thought was cutlass bearing. So when I pulled the boat to move it I checked. The cutlass bearing was tight. No play. So I did not worry about it. Mine only makes the sound at low RPM's in forward. As soon as I throttle up a little it quits.Any one else?