Rudder Vibration, Could Need Some Help

[gjordan]

I know it is cold this time of year, but you might try checking for rudder play while the boat is in the water. You said the rudder is heavy, but in the water (if it is foam filled) it may be light enough to float up and be at a point on the bearing where there is more wear. Just another possibility???? _____Grant.

[Loredo]

donradcliffe,
the "Maxprop sound" or better vibration when the blades have too much play in them or better yet they need a rebuild, I can clearly pick out. I Got used to it over the years.... That one is there until I stop the engine and put it in gear. In fact, at first I thought that the "rumble" was the prop but then listening closer I could say that there were two different noises. The prop and then the rumble. Reason enough for me to get the Autoprop...
One needs a new toy every now and then, right? HA HA

Trailing edge, also a VERY good one. I had this one on my Jouet 37 and solved it. On that boat it did sound different tho. Nevertheless, I'll investigate that one too.

Cheechako,
the play in the cables could absolutly be it. I'll check out if there's any play. Different story will be to adjust the tension on them. How much is too much or not enough??? Like I said, all I've had before were KISS sticks.

gjordan,
diving right now is NOT an option here. Well at least not for me! BRRRRR!
I did what you suggest this summer but could not find anything that seemed out of whack.

Thanks guys, keep 'em flowing. I'm writing down my check list and already got several very good points from ya!

Loredo

[Hydra]

IMO, the cause is what Don Ratcliffe supposed: the trailing edge is too thick and sheds vortices. This is the same phenomenon as when a propeller sings.

Alain

[DeepFrz]

You may be able to prove if it is the rudder trailing edge using a waterproof video camera attached firmly to a pole. I will say though that if it was my boat I would have an emergency rudder fitted to my boat before making any journeys.

Have you tried putting your hand on the top end of the rudder shaft just above or below the quadrant to see if you are getting any vibration?

I once had a steel plate rudder that would flex back and forth but it was much more obvious than your problem. I replaced it with a thicker plate which worked well. I know now that it would have been better to build a properly shaped rudder. That was way back in the dark ages before I had access to all the CF wisdom.

[boatman61]

One word not mentioned to date... cavitation... 7kts+..??

[Sailmonkey]

Originally Posted by boatman61

One word not mentioned to date... cavitation... 7kts+..??

Good point, any small imperfection on either the trailing or leading edge will cause this.

[sailorboy1]

Originally Posted by Loredo

The boat is a 2006 Sun Odyssey 49.
Anything above 7.5 K there's a vibration ( sounds like a rumble ) coming form the rudder area.

If it was me, before spending a bunch of time looking for a "problem" to fix I would check with other Odyssey 49 owners to find out if this was normal for the boat. My bet is that it is and that you don't have a problem really.

[Loredo]

Thank you for your replies!
sailorboy1, if I had been able to find another SO49 owner... The only one I've been able to talk with had a hard time the tell the aft from the bow apart.
Should it turn out that the "rumble" is normal, well then I'd have to say that the design of at least the rudder must have a severe flaw in it.
Hard to believe but could be.
In that case I'd have to seriusly consider DeepFrz's suggestion and have an emergency rudder on board. Yet, at that point I'd rather get rid of the boat!

During this WE I'll see if I can find anything in the steering / wheels / cables and anything else that I can check from under deck. I'll let you know what I find.

Once I'll do the annual haul out in say March, I will be able to follow any and all suggestions you gave me thus far. The watertight camera is on my list already. I got everything needed.

Thanks for your suggestions!

Loredo

[Loredo]

Update,
during the last weekend I went and checked out any and everything I could around the rudder below deck. There's nothing that seems wrong or out of spec. Nothing loose, no corrosion, nothing....At this point I don't know if I should be happy or not.

I did search the web and found the Jeanneau owner forum.
YIKES!!!!
Lokkie here:
Rudder vibration at speed | Jeanneau Owners Network Forum
And here:
RUDDER PROBLEMS | Jeanneau Owners Network Forum

Looks like I'm not alone with my rudder vibration problems on a Jeanneau! Most of all it starts to become clear that the Rudder / bearings design has several severe flaws designed into the system. Maybe better said is: CHEAP!
OK, the whole truth is I knew that I was not buying a HR but...

Looks like I will need to drop the rudder once the boat is on the hard. Trim the trailing edge and replace the bearings with something real.
AAAAHHHHHHHHHHHHHRRRRRRRRRRGGGGGGGGGHHHHHHHHHHHH!! !!!!

Needless to say that right now I'm not a happy camper.

Anyhow, I wish you all Merry Christmas!

Loredo

[donradcliffe]

Looking at the pictures posted by Kordakis Kostas, it appears that the design of the rudder and bearings may not be as much of a problem as the construction. The filler is way too thick on both the rudder and the hull, and they didn't seal the edges of the bearing hole in the hull. It also looks like the two halves of the rudder shells were just glued together with no glass over them.

[HappyMdRSailor]

Originally Posted by donradcliffe

Rudders can vibrate at high speeds, but its only an issue in performance boats. The usual cause is that the trailing edge is too wide and sheds vortices. On a race boat its usually a good sound, because it means you're going really fast.

12 kt indicator on J I'm familiar with... Turns out to be part of the truth here too!

[HappyMdRSailor]

Originally Posted by Loredo

Update,
during the last weekend I went and checked out any and everything I could around the rudder below deck. There's nothing that seems wrong or out of spec. Nothing loose, no corrosion, nothing....At this point I don't know if I should be happy or not.

I did search the web and found the Jeanneau owner forum.
YIKES!!!!
Lokkie here:
Rudder vibration at speed | Jeanneau Owners Network Forum
And here:
RUDDER PROBLEMS | Jeanneau Owners Network Forum

Looks like I'm not alone with my rudder vibration problems on a Jeanneau! Most of all it starts to become clear that the Rudder / bearings design has several severe flaws designed into the system. Maybe better said is: CHEAP!
OK, the whole truth is I knew that I was not buying a HR but...

Looks like I will need to drop the rudder once the boat is on the hard. Trim the trailing edge and replace the bearings with something real.
AAAAHHHHHHHHHHHHHRRRRRRRRRRGGGGGGGGGHHHHHHHHHHHH!! !!!!

Needless to say that right now I'm not a happy camper.

Anyhow, I wish you all Merry Christmas!

Loredo

There are a lot worse problems than this one! Reshaping a rudder isn't so bad... I do like the way these boats pull in a breeze... Great fun!