Question: Is it possible, or better yet, practical, to change a cutlass bearing on a Catalina 310 while in the water? Also, how much free play in the bearing is too much? The engine has 375 hours on it, and I expected the bearing to last much longer.

Answer: It’s possible to change a cutlass bearing in the water, but, unless you’re anchored out in the middle of nowhere and have no other option, not advisable. I say this with the benefit of knowing a cruiser who did exactly such a feat in Costa Rica. It was four days of hammering in the recesses of his engine compartment in blistering temperatures. The echo carried out across the anchorage while a diver dove down several hundred times to check on progress and help remove the prop and shaft. In the end, he did manage to bang the cutlass bearing out from the inside, but it struck me as a little less than optimal and about ten thousand times easier to do with the boat out of the water.

The cutlass bearing should have minimal play in it. If you grab it and can rattle it, it’s time for a new one. As you probably already know it helps holds the shaft in place. The shaft is connected to the transmission, so any wobbling at one end is going to be bad for those important parts and pieces at the other end. There could be a couple of things happening to have worn out the bearing. The most likely is that the engine alignment needs to be readjusted. Engine alignment is critical, and getting an engine aligned into thousandths of an inch tolerances is an exercise in patience, but if you have some and a set of feeler gauges, you should be able to get the alignment down. The rule is that the gap between the couplers should be no more than .001 of an inch for every inch in diameter of coupling. A 4-inch coupler should be within .004-inch. This is actually something that is better to do in the water, as the boat’s hull on the stands distorts just enough to be a factor. Good luck.