Rudder top bearings

[vladkri]

Folks, my rudder makes grinding noise. The noise seems to emanate from top part (bearing?). I think this is original made in 1988. Can anybody help identifying what kind bearing this is and what might be inside which failed? How do I call this design? The pin and couple of rollers seems to be the only thing that holds the rudder in vertical direction. The gap between rudder stock and metal plate (?) is very small 1-2 mm and seem not enough to house any kind of bushing/bearing. There is a bit of play when I turn the wheel. Any insight is greatly appreciated. Many thanks.

[Manateeman]

Hi. I’ve seen this before but I’ve worked for a lot of builders, what boat. Where are you. Almost certain you will need to haul and drop the rudder.
You dig a hole. Sometimes that hole in the top of the shaft...the hole in the middle of the square..is tapped or can be tapped for a eye bolt to help lowering the rudder or pulling it back up.
Is there a lower bearing at the bottom of the rudder. More info needed.
Not a huge project so don’t rob a bank . Any DIY near you?
Manatee

[wingssail]

I think there is a probably a plastic top bearing (bushing) under that stainless steel plate.

You can remove that plate by removing the three long bolts after pulling out the pin with the rollers on it. You are right, this would allow the rudder post to drop down so block the rudder up inside the boat with some supporting blocks under the quadrant before you pull out this pin. (be sure the rudder shaft cannot slide out through the quadrant)

Once you have removed the pin and the three bolts and the plate you will expose the bearing inside, if any. If there isn't a top bearing, (which would surprise me) then what you do will be determined by what you find.

If you see that this bearing is worn and is the cause of the noise you may decide to replace that bearing. Removing it may or may not be difficult. Do not destroy it before taking good measurements. A machine shop can make a new one out of Delrin or UHMP or other plastic. The machined size will be critical for smooth operation. The bearing should be a tight fit in the surrounding build-up but lose enough to turn easily on the shaft. A bearing like this can often be removed after drilling holes in it and screwing in lag bolts so you can attach a puller. On my boat I had to saw it out.

Other possibilities include the rollers themselves or the bearing surface on the shaft. You should be able to see when you disassemble the unit.

[Nicholson58]

https://www.igus.com/iglide/plain-bearing

Chances are high that you can get a replacement here.

[Manateeman]

Before you remove any bolts, pins, whatever...please remove boat from water.
Seek the advice of professional boatbuilders on this repair.
Manatee

[vladkri]

Thanks everybody for the help. The boat was built by a long gone K&C Yachts in Ontario based (to some extent) on Jim Taylor's Starflight 38 design.

[RaymondR]

Looking at the image I suspect that there is a bushing in the part under the quadrant and the flanges where the shaft goes up through the deck is just a waterproofing gland.

[vladkri]

Any idea what are those black spots on the rollers? Those spots are flush with rollers' surface and feel a bit abrasive. Since rollers themselves are abraded in some areas, if I make a copy how important those spots may be? Also, any guess as to what metal are those? Bronze? Thanks a lot.

[Nicholson58]

Originally Posted by vladkri

Any idea what are those black spots on the rollers? Those spots are flush with rollers' surface and feel a bit abrasive. Since rollers themselves are abraded in some areas, if I make a copy how important those spots may be? Also, any guess as to what metal are those? Bronze? Thanks a lot.

Black spots are lubrication impregnated sintered metal.

[Jim Cate]

Do the rollers actually roll freely when you rotate the rudder? And do they alone support the weight of the rudder? While the rudder may be quite heavy, when submerged its buoyancy will reduce the load on the rollers. It could be that the rudder blade has become saturated with seawater and has lost much of its buoyancy, thus increasing the load on the rollers and generating the noise... just speculation, of course!

I would suspect that the rollers themselves are the source of the grinding noise, for even if the likely plastic bushing below the plate is badly worn, such bearings don't usually make much noise.

Another question: can you move the rudder post side to side at the top? If the bushing was worn, that would be a symptom that you might expect to see.

Keep digging... I reckon you can do it yourself!

Jim

[vladkri]

Thanks everyone for the ideas. The rollers are the only rudder supports. As they move each one goes through a) rolling, b) flying over the steel washer/flange and c) sliding over the washer/flange. I replaced one roller with suitable bronze bushing. It also repeats same roll, slide, fly sequence. I think it should really be regular bronze rather than oil impregnated one. That way the inside being lubed has lower friction than the steel plate and the thing rolls rather than slides. Since I poured some of dry lube into the rudder stock gap the noise mostly stopped. Anyhow, the haul out time just around the corner.

[coopec43]

[vladkri]

That's it

[vladkri]

To continue this fascinating journey, rudder is out. I machined top bushing out of Delrin. The original was some kind of plastic encased in fiberglass which I could not disassemble and plastic insert was a bit oval. I just made new bushing thick enough to fit into housing snugly without outer fiberglass shell. The rudder stock is solid 3 inch soft metal, presumably aluminum. To draw a bit more on collective wisdom here, do I grease the stock before inserting it back? If yes, what kind of grease? Recall this will be metal against plastic: Delrin at the top and unknown plastic at the bottom. On pictures notice some wearing I think occurred due to debris falling down the shaft and acting as grinding compound. Also, lower entrance to the tube actually sitting inch or so above the water, so not much of it goes inside. Cheers.

[Bill O]

Originally Posted by vladkri

To continue this fascinating journey, rudder is out. I machined top bushing out of Delrin. The original was some kind of plastic encased in fiberglass which I could not disassemble and plastic insert was a bit oval. I just made new bushing thick enough to fit into housing snugly without outer fiberglass shell. The rudder stock is solid 3 inch soft metal, presumably aluminum. To draw a bit more on collective wisdom here, do I grease the stock before inserting it back? If yes, what kind of grease? Recall this will be metal against plastic: Delrin at the top and unknown plastic at the bottom. On pictures notice some wearing I think occurred due to debris falling down the shaft and acting as grinding compound. Also, lower entrance to the tube actually sitting inch or so above the water, so not much of it goes inside. Cheers.

Based on this chemical compatibility table for actel/Delrin, "grease" doesn't appear to be compatible, but silicone "oil" is fine.