The process may vary slightly dependent on the stern design of a vessel but generally would follow thus: Drain sterntube oil and remove aft seal arrangement  Remove propellor and tail shaft Check alignment of all bearings in sterntube Remove damaged bearing Check condition and dimensions of the sterntube inside diameter, in way of bearing. Machine new bearing outside diameter to match sterntube bore, typically achieving an interference of 0.02 -0.05mm Hydraulically press new bearing into sterntube ensuring cleanliness, lubrication and eradication of any sharp edges. Failure to adhere could result in pick up and damage to your new bearing Once the bearing is in position and settled, re-check alignment of bearings Insert tail shaft, mount seal and mount propellor Fill sterntube with oil.