R21EC vibrations

[bcbud101]

Just curious, I had the cutless bearing and stuffing box replaced before last season on my 2006 R21EC with a 30hp Yanmar. At the time they told me the shaft was bent but was told they were able to straighten to within specs. Throughout the season I’ve noticed vibration at around 18-1900 rpms (not harsh or readily noticeable to anyone else on board but low and subtle) which I’ve come to realize causes the nuts to back off of cabinet doors and them actually falling off after three or four day trips or 10-15hrs running time. I’ve only had the boat a season and a half so cannot for certain say if this vibration was present before the aforementioned repairs were performed. Should I look at getting the prop balanced maybe and if it persists look at replacing the shaft? Or just use lock tight on the cabinet door bolts and keep on motoring…

 

[kelpline]

Humm, that's a tough one. If you have a trailer, pull the boat out and rig a clamped stick to test for shaft wobble as you turn the prop by hand. Also test the propellor tips.

 

[Rode Trip]

Start with the basics. Check the engine alignment first. Give the motor mounts a close inspection at the same time. Shift F-N-R-N-F-N-R a few times while you watch the mounts. Take a close look at the cutlass bearing and see if it's wearing unevenly. Then look at having the prop and shaft checked again.

 

[MassTug]

Hey. For what it’s worth I have a R21 with the Volvo penta engine. Ever since I’ve got it when I had zero hours on the new engine, there has been an intermittent shudder as you describe around the same RPM level so it’s probably not unique to your boat. It does the same thing with my boat sometimes causing some of the screws to come loose. My solution over the last 800 hours of operating time has just been to not leave the engine running at that idle RPM.. Other than that, I don’t have any other issues. My engine mounts are great. I don’t know if it’s something else with your boat, but it is present on mine too.

 

[MassTug]

Hey. For what it’s worth I have a R21 with the Volvo penta engine. Ever since I’ve got it when I had zero hours on the new engine, there has been an intermittent shudder as you describe around the same RPM level so it’s probably not unique to your boat. It does the same thing with my boat sometimes causing some of the screws to come loose. My solution over the last 800 hours of operating time has just been to not leave the engine running at that idle RPM.. Other than that, I don’t have any other issues. My engine mounts are great. I don’t know if it’s something else with your boat, but it is present on mine too.