"Rudder Shudder"

[Nonchalant1]

While cruising the last few weeks, I have occasionally been down in the aft stateroom (1978 53MY) while the Admiral was at the helm, usually with the autopilot, cruising 12 to 15 knots. I heard a strong vibration sound 3 or 4 times per minute, so I opened the lazarette lid and looked in. I saw that when the rudders were being moved and were turning the boat in any direction, there was no vibration, but when it came back to straight steering, the port rudder vibrated enough to make the 2 bolts that connect it rattle. Then it would stop rattling. My concern is that those bolts and/or bolt holes are wearing and they no longer fit the holes correctly and that the rattle will cause enough metal fatigue for them to fail while underway.

Any experience with this? Are the bolts supposed to fit with close tolerances so the rudder can turn but not rattle? When the boat is at the dock, I can push on the hydro arm and the parallel link connected by those bolts, and both will move easily at the bolts about 1/32nd of an inch. I've never touched that area in the 2 years I have had the boat and it has always worked perfectly. The bolts look new, as do the grounding straps for the rudders there, so I'd say they were replaced fairly recently.

Any thoughts would be appreciated, or if any 53MY owners would like to check yours, take a 3 ft pole and push on those arms and see if they can move on the bolts, or if they're close tolerance fittings.

Thanks,

Doug Shuman

 

[captddis]

There are oilon bushings in the hole that the bolt goes through. Yours are worn or broken.

 

[Nonchalant1]

Captdis,

Thanks. I'll call Sam's to ask about replacements. Now I just have to get in there to get at them!

Doug

 

[spartonboat1]

Surveyor mentioned that I need a "re-pin of my rudder arms" at some point, as his noticed some looseness at the rudder (out of the water. However, I am not experience any noticeable adverse steering at this point.

Any reason I could not upgrade and install the oilon bushings? They sound similar to Delrin bushings used in industry and machinery.