Sunday, January 18, 2015

Rudder Post Bearing and Seal

Water has been getting into the engine compartments ever since we bought LUX. Last year we sealed the aft rail and the hull-to-deck seam. Much to our surprise and disappointment, we still had water coming in. The leak causes the engine compartment bilge pump to run about every 30 minutes. We've become accustomed to it, but would prefer that it only came on when there was a problem. So we needed to stop the water ingress.

Rudder Post and Thrust Bearing Before Grease
We identified the source as the rudder tube. LUX has the 40HP Volvo MD2040 engines, which weigh more than the Yanmar engines found on later models. This causes her to sit slightly stern-down in the water. When under way at 7kn, the stern is even lower. The water level is above the top of the rudder post tube and some of it leaks into the engine compartment. The lip seal at the top of the bearing was obviously not working well. There was some speculation that the rudder post was moving enough laterally to wear out the seal.

The rudder thrust bearing shows a lot of rusty color and we can see a steady flow of water when we're under way.  Ed Koplin on Esprit de Mar, had recommended filling the rudder post tube with grease as a way to avoid water ingress and to lubricate the lower rudder bearing. We decided that it was worth a try.


We obtained some stainless grease fittings from our local Ace Hardware. These fittings have a short threaded stud. We drilled and tapped a hole in the upper part of the rudder post for them - one per post and positioned so that it was easy to hold a grease gun on the fitting. We made two blocks to help support the rudder thrust bearing from the pressure of the grease, just as Ed did. Ken Pimentel, who was visiting us in Annapolis at the time, installed grease fittings without the aluminum blocks and it seems to be working fine for him. Everything was assembled with Tef Gel, to prevent corrosion between the stainless and aluminum components.
Upper Rudder Post Bearing

Upper Rudder Post Bearing Being Inserted




















We also removed the upper rudder post bearings, cut out the balsa core, filled with thickened epoxy, and rebedded the bearing housings. Note that each bearing slips into and out of its fitting by turning it on its side. We added grease to the bearing so that it would more easily align with the rudder shaft and would provide some lubrication between the bearing and the shaft.
Final Rudder Post Grease Assembly
Sealed the Rudder Post Upper Bearing Holes

The rudder post thrust bearing was cleaned up and greased. The thrust bearing collar was installed and grease was pumped into the rudder tube until grease came out of the top. The final assembly is shown in this photo.

We've never experienced a lot of friction in the helm action, so the grease didn't change the amount of force that we need to use on the helm. But it has eliminated the source of water in the engine compartment. We now have dry engine compartments and when the bilge light comes on, we know to go investigate.


  -Terry

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