I just had a new cutlass bearing installed while on the hard here in CT. It seems that I can shake the prop when testing about .010 “, I thought it would be less. Is this common or should I inquire of the installer why it’s so much?
Brian Cayer
Spirit~Wind
N30U 419
Deep River, CT
Mine does not budge…
Brian,
I’m unclear how much motion you’re talking about. Taking what you wrote literally, you’re saying it was moving one-hundredth of an inch, i.e., one-fourth of a millimeter. I’m not sure if you meant that or if it was a typo.
Since a cutless bearing has an internal rubber sleeve, I’d expect there’s enough give that it’s possible to push the prop and move it at least that much. I’m not sure I’d be able to detect it myself without using a feeler gauge to measure.
I’m not an expert on the topic, but my general impression is that a cutless bearing is ok unless the amount of movement it allows is detectable by feeling and eyeballing. If you only detected the motion with a feeler gauge and couldn’t detect it by look and feel alone, I’m inclined to say you’re ok.
– Bob
Me Gusta
Nonsuch e26U #233
Hi Bob,
If I grab the prop or the shaft I can move it at least 10 thousandths of and inch. I can see and feel the movement. Before having it done it was about 1/8 to 3/16 inch. I’m going to bring my dial gauge down to the boat on Saturday to get an accurate measurement. I was expecting, like Thor said no movement. I realize that if I used leverage I could compress the rubber and get movement but for a newly installed bearing there should be no movement by hand unless of course the shaft is worn.
Brian Cayer
Spirit~Wind
N30U 419
Deep River, CT
Ours doesn’t budge either. Cutlas bearing was replaced 10 years ago (~1,000 hours) and still tight.
Ed and Marlene Brost
SaSeaCat, NS30322
Sarnia Yacht Club, Sarnia, Ontario Canada
Still confused. 0.01 inches is less than the thickness of three sheets of paper. Either the measurement’s off, or your eyes are sharper and touch more sensitive than mine. I wouldn’t be able to detect that.
When I installed my electric engine a bit over a year ago, the tolerance specified for mating the shaft couplings was 0.04 inches – four times what you’re reporting on the cutlass bearing.
I don’t want to be the guy who sunk your boat, and I’m not Mr. Mechanic, so you may want to hear from others. But “0.01 inches” and “doesn’t budge” sound about the same to me.
Unless I’m missing something, I think you’re ok.
– Bob
Me Gusta
Nonsuch e26U #233
Bob
I will let you know on Saturday what the calibrated dimension is.
To a former machine tool designer
.01 clearance is huge.
Brian Cayer
My two cents: unless you have a problem with an unreasonable amount of vibration while underway, don’t worry about it. Mine definitely has a bit of play. But she runs very smoothly.
Val
I have two experiences with newly installed strut cutlass bearings, and in both cases the clearance was not perceptible. But the shafts were not that old. So I’d measure the shaft diameter next to ensure it isn’t reduced- after all you’re dealing with thousandths. Looking at one company’s clearance guide, https://www.pacificmarine.net/engineering/propeller-and-rudder-bearings/cutless-bearing-clearance.htm , your new bearing seems to be just over the upper limit of new bearing tolerance. But as others have pointed out, it’s well within the clearance for operating. If it were my boat I’d be more curious about the cause then worried that the life of the new bearing will be impacted.
Daniel Weinstein,
Thanks for posting that bearing guide. That lets me know what I should be expecting from my new installation. I will be taking precise measurements this weekend.
And thanks to all who replied.
Brian Cayer
Spirit~Wind
N30U 419
Deep River, CT
Brian,
Do you know what brand cutlass bearing your installer put in?
There’s an interesting article (in addition to an informative rant) on cutlass bearings on the very useful Marine How-to site: https://marinehowto.com/replacing-a-cutlass-bearing-sleeve-bearing/
He swears by Duramax and Morse brands.
I wouldn’t worry too much about being slightly above the tolerance on the Pacific Marine chart.
It’s reporting recommendations established by and for the U.S. Navy, which puts its vessels to harder service for more prolonged durations than our sailboats. (As a taxpayer, I’d certainly hope that’s the case.)
Although one certainly can’t go wrong by following those recommendations, you can be close but outside them and still be right. Or, at least, ok.
– Bob
Me Gusta
Nonsuch e26U #233
Bob,
Thanks for the article. There is a lot of good advice in there. I knew there was some sort of kerfuffle about the cutlass verses the cutless bearing. At least I used cutlass in this strings’ title so we may not be facing a law suit. 
Brian
Spirit~Wind
N30U 419
Deep River, CT
