Ruder Shaft lock nut slakens when sailing

[António]

Hello,

Need some help here. 3 years ago sailing my Bavaria 30 cruiser under autopilot, the rudder top nut came off.
I have replaced all the bearings and top nut brand new from Jeffa. the thing is that the top rudder nut keeps slaking....I have replaced it for a another new one last year..... it was Ok for a few months, but now it slackens again. It is very annoying and particularly not safe at all in longer voyages.
I wonder if i am missing the root cause of the problem!
Thank you in advance for your inputs!

[PEA-JAY]

Hi.

The retaining nut is kind of sliced a few mm from the top and a locking screw, when tightened, compresses the upper thread in a way that under compression it will be impossible for the nut to become undone.
I think vibration is loosening the locking screw for you and once the nut compression is lost, the nut easily loosens.
I suggest you use CRC code 30696 Soft Lock or similar on the locking screw thread to stop it from becoming undone. Clean the screw thread with alcohol to remove any contamination for a good bond.
I mark the nut and top of rudder stock with paint to be sure it hasn't moved!
Regards

[António]

Hello pea-Jay,
Thank you so much for your recommendation. I think it is worth to give it a try.
Any ideas on what might be the vibration source?
Did it work for you?
Regards
António

[PEA-JAY]

I have never experienced this problem but I have heard of it. Your rudder could be a little too loose but it’s difficult to tell with the boat in the water. Perhaps if you give the nut a turn to find out if the rudder remains easy to turn....?
Ideally get someone with experience to have a look at it. About the thread lock make sure you use the soft lock type that can be undone with tools as there is a kind that practically bonds the thread permanently!
Regards

[António]

Thank you! Highly appreciated!