On an inboard boat the steering turns the rudder rather than the engine. The rudder hangs on a rudder post, or rudder stock, which runs up through a tube in the hull and turns in bearings or bushings. At the top a yoke or tiller arm connects it to the steering, whether that's cable and drum, hydraulic rams or an autopilot.

When the tube corrodes it swells, gripping the bushing and the post so hard they won't turn or come out. In this video Jeff and I get Renko's seized rudder post out. I cut the post down so the yoke comes off, then put a sleeve over the top and fill it with a mix of ATF and acetone to soak down the tube. I weld a bar onto the post as a temporary tiller so it can be turned as it drops, which the helm can't do, then heat the tube, drill out the old fibrous bushing and jack the post until it finally falls out. The post had worn where it turned in the bushing, and was eaten away where it touched the stainless rudder.

Then the rudder goes back on, after finishing the propeller shaft.