How much play in Cutlass bearing is OK

[Ray2325]

How much play should be in a cutlass bearing? When I shake on my propellor shaft there is a little rattle in all directions, but no discernible movement. When I tried this on some adjacent boats (all on are the hard right now) most has a little less. Should I replace it, and if so how much should I expect the shop to charge?

[Richard N. Gottlieb]

I owns a 2003 Catalina 36 Mk. II. Earlier this year when I went to inspect the boat during a particularly cold day, I found a small amount of movement within the prop shaft at the cutlass bearing. At first, like you, I was concerned about wear on the bearing and whether it needed to be replaced, a very time consuming and potentially expensesive proposition. When I went back recently to the boat (on a warmer day, but still cold here in New England) I found the movement to be MUCH less pronounced. It was then that I recalled that the shaft is stainless (ha ha) steel and the bearing is made of brass and that the expansion and contraction rates for these metals is different. I think that unless the bearing on your boat is fairly old (say 7-10 years), it may be due to the same thermal issues and that there is nothing to worry about as a result. Food for thought!Best regards!Rick Gottliebs/v Wind Angel#2115

[Ray2325]

Thanks. I do feel a little better about it now. I really could not move the shaft, but it did rattle just a little bit, and it was really cold that day as it has been for the past month.

[KorculaChris]

and when in the water it'll be wet. The water takes up a bit of the slop.

[Tim Haibach]

In Nigel Calder's book "Boatowners Electrical and Mechanical Manual", it states that anything more than 1/16" play per 1" shaft diameter should be considered for replacement. Once a cutlass is replaced, the engine alignment needs to be verified. My particular engine has a max variation of .003" between any two points of the mating flanges. It is recommended to check the alignment on your engine annually.Excessive vibration under low RPMS may be an indicator that it's time uless it is an extremely cold day when you start up.