My 1983 Catalina 30 tall rig with a atomic four engine has started making a knocking sound similiar to a loose hatch or warped storage compartment cover. It happens at about 900 to- 1000 rpm then quits and runs smoothly on up to 1800 rpm. It can be heard distinctly from outside the boat. I have had a new cutless bearing installed engine mounts checked, shaft aligned,pyi shaft seal and rudder post checked. I have had guys in every compartment of the boat underway we cannot identify exactly where the sound is coming from. There is minimal vibration. Have even run with different backstay adjustments. The noise does not occur during a static test in the slip. The 2 blade prop looks good, but before I get in the cold water to remove it and send off to the prop shop any ideas?
noise under power
- Thread starter pelikantwo
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Do you feel it stronger in any particular place on the boat? Had a similar issue with mine after a bearing replacement and it ended up being a misaligned shaft and the prop was cavitating. At low and high RPM's it was not noticeable and it would also go away when I was at full power.
I know you said you aligned it but could something have caused it to go out again?
I know you said you aligned it but could something have caused it to go out again?
Jack: Thanks for your reply. That's interesting At coffee this morning withmy crew,it came up that the first race of the season in feb.was extremly rough for an old boat 20 knts gusting to thirty. no one remembers hearing anything but we were pretty preoccupied. had not used the boat since then until last weekend. The alignment was checked in Dec when a new cutless bearing was installed. Given your expeirence I think it wise to check the alignment again first before messing with the prop.
I'll let you know. Thanks, Lee
I'll let you know. Thanks, Lee
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