Machining uhmwpe plastic

The boat was raced two weekends ago. This boat is dry sailed and kept on a trailer. Inspected the bearings after the race. The bottom bearing didn't stay in place. It rotated 90* on the shaft and slid down the shaft. It can't come out because of the rudder. The helm was supper smooth.

My friend wanted a back up set of bearings and a spare collar that holds the shaft in the boat. The fitting for the tiller will also keep the rudder in the boat if the collar should fail. So I made another set of bearings and a collar. I made the OD of the bearings to be a tighter fit. It will take some force to put them in place. I also made the ID slightly bigger. The first set only had .0005 clearance between the rudder shaft and the bearing. I was shooting for a .001 to .002 clearance on this set and ended up with a .0035 clearance. Going to get the new bearings installed in the next couple of days. My friend wants them in by Labor Day weekend. That's when the SC27 National Championship Regatta is happening. His boat under the previous owners won the Nationals twice.

It has been a fun project.
 
Inside of the boat, can you machine a collar/glue a collar to the bushing, so it does not slide down? Install the bushings as the rudder is pushed up through the hull.
 
The bushing fits in a 2" PVC coupler that was fiberglassed into the boat when it was made. My friend has talked to the man who made the boat. Might have been the shop foreman. The rudder shaft support (wrong term??) is a piece of 2" PVC pipe with a coupler on each end. These are standard off the shelf PVC pipe and couplers. The bushings were inserted into the couplers and then a jig was used to hold the everything in place while it was fiberglassed into the boat.

My friend tried to do what you are suggesting and it didn't stick. The bushing sliding down the shaft is not really the problem. It can only move maybe 1/4" to 3/8." The real issue is that the bushing rotated. We don't know if it rotates every time the tiller is moved when sailing. Or only rotated one time. The bushing does not move when the tiller is moved with the boat on the trailer. And my friend was not able to push the bushing back up the shaft. What we are concerned about is the bushing rotating in the coupler which will wear the soft coupler over time. The man who built the boat suggested using 3M 5200 to glue the bushing to the coupler. In the original construction nothing was used to glue the bushing to the coupler. It was just a tight press fit. Also the hole in the hull was just big enough for the shaft to fit. So the hull kept the bushing from sliding on the shaft. This hole had to be enlarged to remove the old bushing.

I have looked at another boat that had the bushings replaced. That boat's bushing extends just below the hull surface. I don't know if it is glued in place. And I don't know if it rotates when the tiller is moved when sailing.

We are going to mark the bushings, top and bottom, to see if they move when the boat is sailed.
 
After racing the boat we can not see any further movement in the bottom bushing. There has been no movement in the top bushing.

I found an ABS fitting at Home Depot that I was able to machine to fit the cracked top coupler. Haven't tried to install it yet. The stainless steel hose clamp is keeping everything together so far.
 
Temporary, permanent fix :grin:
 
The hose clamp is temporary. My friend thinks it is ugly. Probably try to get the ABS installed before the next race in a week or two.
 
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