Our Mk I has some play in the tube. The rudder shaft is approx. 3" stainless passing down through a fibreglass tube. The fibreglass slowly wears away leaving the slop which makes the clunk.
There is a recommended fix from Catalina, drop out the rudder, clean inside the tube, grease the stainless shaft and reinsert. Seal the bottom of the shaft exit. Fill with runny epoxy and rotate the rudder as the epoxy hardens.
We've not done this yet...

Just how tight should the steering cables be? I had my cover off to do some wiring and noticed that there was a bit of play in the cables.

Others will have a better knowledge than me, but the cables shouldn't have any 'play' they should be snug without being drum tight. There is an adjustment on the quadrant under the cockpit floor. Check that the cable is in good condition as well (esp. where they bend to go under the clamps on the quadrant), as ours looked only a 'little dodgy' but broke under pressure one windy day...
Hope this helps :)

[url]www.edsonmarine.com[/url]

I believe they have manuals on their website.

My Edson manual says about steering cable tension (paraphrased): If you lock the wheel you should have no play in the quadrant/rudder shaft assembly. It also says too tight tension willl decrease 'feel' in the steering.

Mine (after 20 years) are too loose; I'll be tightening them shortly. I can move the quadrant over 1/4" with the wheel locked, and they feel slack.

To follow up on this since I was the one who asked, Silver Flight quotes it exactly. I spoke to a tech rep at Edson and he said 1" in play in the cables is what they think of as "in spec" and no movement by hand on the wheel ofthe radial drive unit with the steering wheel locked.

I am just at the limits of spec and adjusting them looks like a b---h. I just know I am going to drop the locking nut into the bilge since there is so little room to get your hands and a wrench in there.

Edson does have a manual on-line but when I tried to download it, it locked up my PC. I contacted Edson and they said they have received a number of complaints about this and sent me a seperate PDF file of the instructions, but the maintenance section is no more than what everyone probably has in their Catalina provided info from when the boat was new.

The adjusting eyebolt nuts are on the bottom of the wheel on the radial drive system... that's hard to tell from the illustration because its so small.

Have a look at my article 'Installing a Below Deck Autopilot' in the Technical Upgrades library. It shows several photos of the quadrant (actually, I don't think it's a 'quadrant' because it's a complete 360 degree wheel), some that show the adjusting nuts. I doubt the lock nut will need be removed; just backed off a couple turns.

You probably won't even have to crawl into the lazarette to do the adjustment, as the access (on the Mk II) from the aft cabin - cover off - is pretty good. I installed my rudder position sensor there and it wasn't an overly difficult location to work in.