USAMARINE Web Group - Captains' Corner Boatbuilding Tips

Bertram 31 Rudders - Wear and Adjustment

"Should the rudders have any movement in them or should they motionless? if they are not suppose to have any movement how can you tighten them? thanks in advance"

There's usually a small amount of play from years of wear. The lower through hull casting is not a tight fit but more than a slight rattle would be excessive wear to either the port, rudder shaft or both.

The upper end of the shaft should be captured by the flange bearing and any lateral movement here is usually due to the flange not being tightly bolted down or deterioration of the rudder shelf.

You should have a locking collar on the shaft just above the flange bearing. If the rudder is loose vertically, pick the rudder up to it's fullest extent, and re-set the collar down against the upper bearing. Drill a dimple in the shaft for the locking bolt to fit into for a safety measure...

Some boat owners have done away with the upper bearing and opted for a thick plate of bronze, brass, or aluminum in place of the bearing. If you have this configuration, be sure there's no play between the shaft and the hole.

Wear on the through hull rudder port or an upper plate bushing is normal, and aluminum will wear faster than bronze. The shaft material is usually either bronze or stainless steel. Old bronze shafts are commonly worn more so then the port.

Ports can be removed, over bored and sleeved with silicon bronze bushing stock. Just about any machine shop can handle this. Same goes for sleeving the shaft, but you'd need to do that in conjunction with sleeving the ports so that the two match correctly.

If, when you grab the rudder blade and try to move it laterally and get no more than a bit of rattle, you're OK with what you've got...

The final adjustment should a slight toe out of the blades away from the center line of the boat. In other words the aft edges of the blades will be further from the center line than the front edges of the blades. This is done by adjusting the end caps on the tie bar. Only toe out by a 1/2" on each side. This assures that there is always some water pressure against the blade faces when underway. This reduces any rattle and slows down undue wear.

Toeing out the rudders

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Capt Patrick McCrary

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