Assessing rudder bearing(s)

[[2574]]

How does one know when one's rudder bearing is u/s? I've a large (half skeg hung) rudder and there is a morsel of athwartships movement in the rudder blade which can be felt when she's ashore and the blade is wiggled. There are no symptoms when at sea. The boat is a fifteen year old Nauticat. I believe that there are two bearings because there are two grease points on the shaft.

Thanks in advance of responses.

rob

 

[sailorman]

How does one know when one's rudder bearing is u/s? I've a large (half skeg hung) rudder and there is a morsel of athwartships movement in the rudder blade which can be felt when she's ashore and the blade is wiggled. There are no symptoms when at sea. The boat is a fifteen year old Nauticat. I believe that there are two bearings because there are two grease points on the shaft.

Thanks in advance of responses.

rob

grease it up & it will tighten up
i have a 5` long spade rudder so the play is accentuated at the bottom,grease her up & it ok no play at all . i replaced my bearings 14 yrs ago

 

[Neil_Y]

depends on the bearing type/material, wear does acelerate with increased clearance, but how much is it used and are you planning a long passage.
grease might be all you need, or it coul help as a temporary measure.

We supply clearance figures for max movement when bearings should be changed.

 

[[2574]]

depends on the bearing type/material, wear does acelerate with increased clearance, but how much is it used and are you planning a long passage.
grease might be all you need, or it coul help as a temporary measure.

We supply clearance figures for max movement when bearings should be changed.

Neil

Thanks for that. No long passages planned; weekend sailors at present. I'd be grateful if you could let me have your clearance tolerance figures.

Rob

 

[Neil_Y]

Neil

Thanks for that. No long passages planned; weekend sailors at present. I'd be grateful if you could let me have your clearance tolerance figures.

Rob

Clearances depend on ID and wall thickness, and will be different for different materials, this is for Maritex, each manufacturer should be able to give you these figures for their material.

go to this page and an excel calculator can be used or downloaded.
Enter the shaft OD in the first box and bearing carrier ID in the second.
http://www.h4marine.com/Downloads/Maritex AQUARIUS General Calculator REV 20100519.xls

The table then gives fitting clearances and running clearances, there is a break down of the three factors for clearance under neath and to the right a wear limit for change.
The three factors are Moisture, Thermal and running. Thermal is the biggest, so bearing materials with lower thermal expansion can run closer tolerances safely.

I hope this is useful.