C-30 shaft vibrations

[Rich]

HelloI have a 1987 Catalina 30 with a Universal MX 25 3 cyl. diesal. I have PSS shaft seal which is really nice. Does not leak at all. I have also installed a flex coupler to help reduce vibration. My shaft seal seems to be knocking when I reach 2500rpms and over. I believe this is caused from excessive vibration. I took the shaft out and had it shortened (to make up for what the flex coupler added. about 1 1/8") at which time the machinist said he had to straighten it slightly. It is a bronze shaft and I assume it is original. I have aligned the engine according to factory specs. I also had my prop checked for balance.I would love to hear from anyone else on wether they have vibration problems or not. Any advise would also be appreciated. I am intending to have the the shaft checked again for straightness. Thanks for all your input.

 

[Chip]

Could it be the cutlass bearing?

That can cause vibration

 

[Ron]

Zinc?

I recently launched after putting on a new bottom and zincs.After turning the screw for about an hour I noticed a vibration and sound coming from below.I soon docked and went for a swim. I too was worried about a cutlass bearing, but I checked for play before launching.To my suprise it was the shaft zinc. Some fool "myself" did not tighten it all the way!Hope your vibrations end this easily...

 

[Walt]

I had vibration too

I have a 1985 catalina 30 with a universal M-25 and when I bought the boat i thought the vibtation was a little high. To make a long story short I went to a 3 blade prop and it runs much, much, smoother.

 

[Rich]

Thanks for your replies.

Thanks to all who replied. I also in response to the replies I have relplaced the cutlass bearing as well. The zinc was tight when the boat was hauled in the fall. I have always had a 3 blade prop and is the prop which I had balanced. Thanks again to all who responded.