6. Hull

Note: I insert records as I come across good advice in current email threads or as I get a chance to review the archives. For that reason all elements of the index are not populated. If any C470 owner does the research and sends me text for a record, I'll include that with attribution. ...Joe

6.1. Rudder & bearings

6.1.1 Rudder bearing replacement.

Problem: The problem presents itself only under heavy pressure - wind over 18 kts. It is when the boat maybe gets a little overpowered and I mean really
stiff that I could probably break something if I tried to meet the pressure (big strong boy). i have actually had to tell people who are at the helm to not over power
the wheel pressure. I'm not talking about holding on tight, I am talking pressure almost like the rudder is too big (which is great and adds to the handling
characteristics). [Larry; Comfortably Numb; 73; 3 Dec 2009]

Advice: The rudder problems are the result of movement in the upper bearing assembly and lower bushing of the rudder post.  Charlie M (LADY) is working thru this issue now in the BVI after a rough trip down here.  I had the identical issue years ago.  

Checking for wear: To check for bearing wear or bolt hole elongation by removing the cockpit access plate and turning the wheel back and forth, remove the entire access plate between the lazarette seats.  Then move the helm to the limits in both directons.  You may have to move it sharply for the last few inches.  If you see any movement of the LOWER bearing flange, then you have elongation of the bolt holes under that flange.  If you don't have difficult steering at the time of this test when side loads are placed on the rudder (such as running with weather helm), you will have when the elongation becomes elongated enough.

Bearings: The upper bearing is a true bearing. It is encased in two flanges. There is a very nicely done diagram of the steering mechanism in your Owners handbook.  The upper bearing sits inside the upper flanges. It is a plastic bearing circular in shape to fit around the rudder post but inside the hold-down flanges. I had mine machined out of an HMW (hi molecular weight) plastic and they seem to be doing just fine.  However, the key is having an aluminum plate machined to fit outside around and between the two flange halves.   That will stop any further elongation of the bolt holes and the resulting grinding of the circular bearing when side loads are placed on the rudder. The way the upper assembly comes from the factory leaves  "moment arm" between the flanges/steering box.  Any looseness of the bolts just allows them to "work" in their respective holes and the problem is then commenced.  A flat spot develops on the bearing and then the steering is trying to work against a flat spot on the bearing.  The more the upper post "works" the longer the flat spot becomes and the problem just gets worse and worse.

Replacing the bearings: You have to haul the boat and drop the rudder then replace the upper bearing (that is the ONLY true    "bearing"   in the assembly) and the lower bushing while keeping the rudder post in perfect alignment. Plan on replacing the center bushing also. (Better to replace all three at the same time than try to use a worn center bushing with new upper and lower parts)  Sounds difficult but it actually is fairly easy.  The issue is that the design of the upper bearing assembly may allow the bolts holding the upper bearing assembly to the boat to "walk".  Thus, when a heavy side load is placed on the rudder, the upper bearing grinds against itself inside the upper bearing assembly thus requiring massive strength to move the rudder.  The fix is not only to replace the bearings but to have your local yard build a "collar" which fits between the upper and lower bearing flanges.  Mine was machined out of a solid block of aluminum, drilled to fit the holes holding the bearing assembly together and then put in place.  This prevents the upper bearing assembly from "walking". The kicker here is that the bolt holes in the "box" directly under where the upper bearing assembly is located may have elongated significantly due to all the "walking" of the bearing bolts(that is what Charlie M on LADY is waiting to see).  If that is the case, then your machinist/yard must either drill out the holes and put aluminum guides in the former bolt holes or use something like Formula 27 to fill in the holes, re-drill them and then re-assemble the bearing assembly.

The hardest part of the re-assembly of the bearings is getting the rudder post hanging exactly straight down so that all the bearings/ bushings line up when replaced and are 5200'd in place (The lower bushing gets the 5200). You will also need to replace the packing in the center bushing  so make sure you have new stuff  on hand when starting all this.  If the boat is set in the jackstands properly (use a plumb bob when they are doing it) you should be OK. I had a "pin" made to use for alignment and sent it off to one of our Owners but I don't remember who has it now. The pin was used solely for alignment purposes when setting the bearings/bushings and worked perfectly for me.  WHen the rudder post was re-inserted the alignment was perfect; my steering (according to Mike Yorke, Certa Cito # 108) during the Caribbean 1500 last month) is smooth and trouble free under any and all sea conditions.

The bearings can be ordered from Catalina or from  another supplier in Florida.  I had mine custom-made to slightly tighter tolerances than the Catalina bearings/bushings but that was due to my rudder/steering (Ted at SEASIDE BOAT WORKS at Jabins YARD in EASTPORT; he is difficult to work with but probably the best steering guy on the east coast))guy being  super-anal about doing it right.

Once fixed, the problem cannot re-occurr.  I will get some pictures of the aluminum collar I currently have in place and send them off for publication on the website. If anyone has any further questions please do not hesitate to contact me.  I have good comms aboard BECKONING, (AT & T, SKYPE, satphone) so will be glad to discuss this issue with anyone facing it.  You MUST fix this problem when/if it occurs because it won't fix itself and it will become progressivly worse as the upper bearing wear/bolt walking increases.

Owner: Jim Wholleber
Boat: Beckoning
Date: Dec 09


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