shaft woes

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t-bird

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May 23, 2009
1
2 c-30 san fran
Im having problems diagnosing my prop shaft wobble. Heres a bit of recent history: After hauling my '78 Catalina 30 I motored back to dock for 3 hours. Everything went smoothly. 2 days later I went out sailing and on my return I noticed vibration then,bang, huge shuddering.I got to dock and called my diver who informed me my cutlass bearing was tight, but my once 3 bladed prop was now a 2 blade prop.(I must of over-cleaned the prop in dry dock).I puchased a new prop (same size/pitch) and the diver installed it. But there was stilll wobble in my stainless 1" 7-year old shaft. I then split the coupling from my atomic 4 and backed the shaft off. I noticed that I could move the shaft any direction about 3/4 of an inch. I pushed the shaft back into place and everything seemed to line up very well. when I hand turned coupling and shaft there seemed to be wobble still.Questions: Could I have bent my shaft? Is there a way to check shaft/coupling squareness in the water? Should I have 3/4" play when shaft is de-coupled? Any advice would be greatly appreciated. THANKS
 

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Any chance the engine and shaft misaligned during the time it ran with the broken prop? Misalignment will cause a vibration that sounds like someone is banging on the hull with a mallet. The cutlass bearing may also be unevenly worn and may appear intact to a diver only able to see a limited portion of the bearing and maybe not get a good feel for any play that might be present. Have you checked with Don Moyer at moyermarine.com. When I had problems with my A4, he would answer any questions in the forums. He even got on the phone with me a few times and talked me through diagnosis and repairs.
 
Feb 26, 2004
23,081
Catalina 34 224 Maple Bay, BC, Canada
If it's moving 3/4 inch inside the boat, there could be damage to the stern tube and/or strut. Think of how it's arranged: coupling, stern tube, strut with cutlass bearing inside the strut. Good luck.
 
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