Cutlass Bearing Replacement

[claymore]

Can anyone hazard a guess as to how long they lasted before requiring replacement?

Probably one of the dimmest questions I have asked.....!

 

[TQA]

On my first boat I did not replace mine in 7 years.

This one seems to need an annual change but I will investigate more next year as this seems too often and I might have a prop balance issue.

 

[MoodySabre]

I've had my boat 7 years and it needs doing now - don't know how old it was. the answer is "When it is worn" Wiggle the prop - there shouldn't be much movement.

Article here http://www.diybob.com/diyCutlessBearing.htm

 

[rob2]

I do recall replacing a friend's cutless, because although the old one was definitely past its best it didn't noticably vibrate. Unusually the cutless was in the skeg and only 2" long on a 1" shaft, so we had to cut a new one in half. I bet the new owner will lose the "spare2 half before he gets round to replacement.

All this sort of demonstrates that the longevity of the bearing depends on the original design of the sterngear, how often and for how long it is used, water conditions and alignment of the shaft. So if any one of these conditions reaches critical, then it will wear fast. Keep everything within acceptable limits and you may think it everlasting.

Rob.

 

[robmcg]

Must be a popular job at the moment as ours is being changed too. Ours was badly worn at the bottom because of poor shaft alignment. The symptom was a distinctive vibration through the cockpit sole above about 2000rpm. We have the added complication of changing the engine mounts which were also far gone and contributed to the alignment issue.

 

[Topcat47]

The better the alignment the longer they last. I had a broken engine mounting that ruined a cut less bearing in a season. If you're replacing them every year, I'd look there.

 

[Blueboatman]

Wear being related to the ageing/wobble rate of any rubber engine bearers and the siltiness of the sea that it operates in....

 

[neil1967]

Replacing ours this year. I think the PO had it replaced in 1997. There is now noticeable movement and a rumbling when under motor, so I am getting it done.

Neil

 

[charles_reed]

I do recall replacing a friend's cutless, because although the old one was definitely past its best it didn't noticably vibrate. Unusually the cutless was in the skeg and only 2" long on a 1" shaft, so we had to cut a new one in half. I bet the new owner will lose the "spare2 half before he gets round to replacement.

All this sort of demonstrates that the longevity of the bearing depends on the original design of the sterngear, how often and for how long it is used, water conditions and alignment of the shaft. So if any one of these conditions reaches critical, then it will wear fast. Keep everything within acceptable limits and you may think it everlasting.

Rob.

I suspect you're right - mine too is a 51mm long bearing on a 25mm shaft. From experience it does about 2000 running hours, but if i get a wrap, it almost always needs replacement, if not immediately very shortly after.
Changing is vastly easier with a phenolic-backed bearing, than one that is brass-backed - there are, however, many other bearing systems out there than the conventional cutless bearing which offer theoretical advantages.
I use Countrose Bearings:-
www.countrose.com/content/index.asp

 

[Neil_Y]

We recommend replacement when there is around 2% of shaft diameter as play or clearance for a composite bearing.

As an example a 1 1/2" shaft bearing should be replaced when there is close to 1.00mm of play (radial displacement), new the bearing would have 0.13mm radial displacement. How long they last is down to all the factors mentioned and also the material the bearing is made from. There are alternatives to rubber.

 

[fisherman]

2" shaft, 1996, done 12000 hours, max 700 (shaft) RPM. But if you have a sandy bottom.....

 

[Dill et Bound]

All above posts are quite right. An engine mount going, Change in location, can effect bearing. Neils post re wear is about right, any more you get vibration, worn engine mounts, vicious circle.. If you do need to change them, Top Tip avoid too much heat.. Good puller, bar disc, fine thread, You dont want to ruin a good line up. Good Luck.. Happy New Year..