Is the engine properly alighned with shaft? Seems to me that a cutlass going out that quickly on a sailboat which does not have high RPMS (and likely not a lot of engine use) would be a concern for me.

65 hours? That thing is brand new.

I am no expert. I am just giving the thoughts coming off the top of my head. BTW, that should all be fixable, so I would not make it a deal breaker. You just need to find out why. My first guess is an alignment problem.

Brian

 

Check the engine mounts, I suspect alignment issue as well, but thats just a guess based on my experience with a similar issue I had.

 

In-the-water is the best time and place for an alignment check anyhow.. so split the coupling and use a feeler gauge or even just a clean piece of keystock to see if the clearance is similar (very) all the way around. Gross misalignment will be evident without the need for .005 inch feeler gauges.

 

Does surveyor reccomend replacing the cutlass bearing?

My boat also had play in the cutlass as noted by surveyor during purchase. He also was not concerned (although my bearing was very old unlike yours). My bearing/shaft probably has 1/16 inch play. I will replace on next hull out. I should have replaced when I had the survey, but survey said it was ok.

As others have said, I think you are ok. Replace bearing, check engine mounts and allign- should be good to go.

What is the failure mode from a worn cutlass bering?

 

What is the failure mode from a worn cutlass bearing?

With longish shafts and a sloppy cutlass bearing you can develop 'whip' that would be mainfested as some unusual vibration, most likely only at certain RPMs or beyond certain RPM thresholds. If the rubber is truly gone, then you will get the grinding noise and rapid damage to the shaft and the bearing shell.. don't think it often gets to that stage, though.

 

BTW, when our prop got junk on it, we felt vibration at low rpms. Did you feel that on your test sail?

Brian

 

Not at that stage yet Brian,
She has just been floated and is going for a topsides paint job. After that they will step the mast and we will do a test sail with the surveyor. He seems very capable and he does not think it needs action until we change the prop at the end of the season so I don't think this is serious but we will look at the alignment as described.

What a lot to learn.....

Thanks

 

I have seen that happen with an unbalanced or damaged wheel. People ignoring it till it develops into a larger problem. I tell my customers an unbalanced wheel is like an unbalanced tire. Maybe just a little vibration but over time it will slowly wear out other components.

 

Agree. It is on top of my list. Don't motor much, but will rework asap.
Regards

 

How do you balance a prop? Just make sure it is clean?

Pity you cannot take it to the local tyre shop....

 

A local propeller shop would be able to clean and balance your prop. It should cost ~$100, if you can get it off the shaft. Many prop shops do not work ON boats.

New England Propeller is located in Plymouth, MA, and Roses in Glocester, MA are two recommended ones.

 

Thanks for the info.

 

check motor mounts. a problem is usually reflected elsewhere in the line of items to be addressed. alignment is important. 65 hours can be good IFF the engine was on good mounts. if not, can be what you found.

 

As a bearing supplier it can often be bearing carrier alignment that is not noticed, look carefully at the clearance at either end of the P bracket if the boat has one.

It is also not engine hours that wear a bearing as when it is running the shaft is on a film of water so there is no wear. The bearing material (or shaft) wear at start up and run down and the wear can be accelerated by the type of sand or silt in the water column. So a boat that does many short runs (as yachts often do in the Solent) will see higher wear than a motor boat. Most yachts will start and stop the engine twice for every journey as they motor out of or into a marina/anchorage a mobo only does this once so will see half the wear.

Acceptable bearing cearances will differ for different bearing materials/suppliers.

 

I use a piece of shaft the same diameter as my main shaft with the taper cut on it, and two drill holes ,one on either end. I put the prop on this taper. A jig which holds the prop, on this shaft thru two sharpeened bolts in these pin holes lets me see which is the heavier blade. If I grind the heavier one down, to the point where, when I spin the prop, it stops at a different point every time, the prop is balanced. Leaving this shaft a bit long, lets you hold a patten on the blade and line it up with the shaft for pitching it.

 

If your prop is dog-eared, you can often fix it in-place yourself with a couple of opposed small sledge hammers. Getting the prop off some boats is a major operation. Sailboats usually have very short(4' or so) shafts, so whip or a bent shaft is seldom the problem. You're also not dealing with a strut (or are you?) that's out of whack. I would agree with those above that the prop is likely the problem. Even a small misalignment at the coupling would not cause premature bearing wear like that.

Also check the water passages that allow water flow into the bearing. A dry bearing fails quickly.

 

Holding a dial caliper on the shaft, while slowly turning it, will tell you if it is bent

 

I take you mean a dial gauge (DTI) not a dial caliper - or am I missing something?

 

It's tough to try to use a gauge on the shaft when it's in the boat. The right way is to get it out and set it on two sets of bed blocks (you can make them from any sturdy metal wheels, even old roller skate wheels will work) with a stable, moveable platform for the depth gauge. Then you can rotate the shaft on the blocks and check it for deflection all along its length, including the taper and the keyed section that enters the flange.