Cutlass bearing

purplerobbie

purplerobbie

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The surveyor said the cutlass bearing needs replacing so while the boat Is out of the water I decided to do it.

The cutlass bearing is in a bronze casting that is bolted onto the back of the keel.
There are two bolts (one top and one bottom) that look like they hold the casting on but once you removed them you then have to unscrew the casting to take it off. Is this the normal way they are fitted?

The cutlass bearing is just a rubber bit inside this? Is this right? All the cutlass bearings I have seen have been a bronze tube with the rubber inside. Do I take this bit of rubber out then fit the bronze tube type inside the housing? Or do I have to replace the complete unit fitted with a new bush?

Rob
 
purplerobbie said:
The surveyor said the cutlass bearing needs replacing so while the boat Is out of the water I decided to do it.

The cutlass bearing is in a bronze casting that is bolted onto the back of the keel.
There are two bolts (one top and one bottom) that look like they hold the casting on but once you removed them you then have to unscrew the casting to take it off. Is this the normal way they are fitted?

The cutlass bearing is just a rubber bit inside this? Is this right? All the cutlass bearings I have seen have been a bronze tube with the rubber inside. Do I take this bit of rubber out then fit the bronze tube type inside the housing? Or do I have to replace the complete unit fitted with a new bush?

Rob
Click to expand...

My understanding is that trying to replace the rubber insert will result, on a DIY basis, in an unstable mounting and soon lead to failure. Best replace the whole unit with rubber interior mounted in its sleeve.

PWG
 
Cutlas bearing

Sounds to me like there is some duff info here, the rubber is bonded to the bronze tubing in most, or infact all cutlas bearings, attempting to replace the rubber will be impossible, you would have to remove a new one from a tube to have a new one in the first place.
Remove the drive shaft, then use emery paper or some other abraisive to reveal the bronze part of the bush, you will then need a long length of studding to draw the old one out and the new one in, make sure there is loads of lube on the new one and if its tight try some heat on the outside of the P bracket, this should expand it enough to release the old bearing. You will need a length of steel tube longer than the bearing and a few mm bigger than the O/D of the new bronze tube to allow the old one to draw out.

If you get stuck PM me and I will go into more depth.
 
You were right in the first place. The two screws just stop the housing from turning. It is screwed onto the stern tube which is bonded into the boat. Take the screws out, unscrew the bronze housing - you likely will need a pair of stilsons as it will be well stuck on with sealer. The housing has the cutless bearing inside. It is a press fit, but is usually locked in place with a grub screw cunningly hidden under years of AF. Clean the AF off, take the (usually allen headed) grub screw out and you should be able to press the bearing out.

New ones come with either brass shells or phenolic resin shells, with brass being more common. They are standard sizes, widely available, but make sure you get exactly the right ID - probably 1" in your case. Press back in, replace the grub screw, screw back on, bedding in a polysulphide sealer and job done.

Can be done manually, but a hydraulic press makes it easier - any competent marine engineer can do it. Lake Engineering in Poole just did one for me - picked it up the next day.
 
It looks very like the rubber goes right to the edge of the housing and the housing appears to taper?

Definatly don't think there is a bronze tube in there?

Rob

Edit
When I put it all back together again is there any point in using sealant? It has holes in it to let water in.
I was thinking of using some sort of grease so if it need to come apart again it will?
 
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Lots of good advice so far, but inspect it carefully as I have come across plain rubber inserts, so it may not be in a hard shell (bronze or phenolic).

Once you have the old one out, measure the ID of the carrier accurately and you will then be able to look at bearing options. If it is just a rubber insert it may be quite a thin walled bearing.

The options are now rubber in a shell or composite. Bedding the bearing on epoxy as a clearance fit in the carrier is the easiest DIY fitting solution, no press or hammers required.

The manufacturer of the bearing will give you the finished clearances you need.
 
TNT said:
Sounds to me like there is some duff info here, the rubber is bonded to the bronze tubing in most, or infact all cutlas bearings, attempting to replace the rubber will be impossible, you would have to remove a new one from a tube to have a new one in the first place.
Remove the drive shaft, then use emery paper or some other abraisive to reveal the bronze part of the bush, you will then need a long length of studding to draw the old one out and the new one in, make sure there is loads of lube on the new one and if its tight try some heat on the outside of the P bracket, this should expand it enough to release the old bearing. You will need a length of steel tube longer than the bearing and a few mm bigger than the O/D of the new bronze tube to allow the old one to draw out.

If you get stuck PM me and I will go into more depth.
Click to expand...

In this case the bearing isn't in a P bracket it's in the keel.
Also not all bearings are rubber bonded to a bronze tube you do get some that are just rubber. I replaced mine at the beginning of the year. I assume it was the original one. It was just rubber mounted in a P bracket. I replaced it with the common type (bronze tube)
 
Just spoke to Crowthers in Manchester they knew what it was straight away.
They said its a quite old one and is solid rubber that will have to be machined out.

When its out the space left is to big for the standard bronze tube type so the housing will have to be sleeved down.

They said it will cost about £60 to do or a new housing is about £180

Result

Rob
 
That sounds like you have a Stuart Turner stern tube, which I have. You have two choices. The rubber bush is still, I think, available. It is not plain rubber but has grooves in it rather like a cutless. Or, as suggested have it machined and sleeved to take a standard cutless, which is what I have done. The machinist will also need to cut the length as an ST is 3 5/8" long compared with 4" for the cutless.

The sealer goes between the flange and the deadwood - just a small amount. Check the water intakes in the little "ears" are clear.
 
Just to confuse the issue ,it is possible to have a mixture of imperial and metric on the same cutless,my last boat had a 40mm shaft and the cutless outer was imperial ! If you have room between the prop and cutless leave about 3/8th of an inch of the cutless stuck out.but before you do that drill 2- 1/4 inch holes diagonally opposite,try not to cut thro, the rubber, then you can make an extractor with 2- 1/4 pins in to remove the cutless,using the prop shaft centre screw hole to put the extractor screw in.Obviously you do not want to put to much tension on the flexible coupling. Works well for me but i do put silicon grease on the cutless before installing .
 
LadyInBed said:
If it is possible DON'T cut to length! - The 3/8" sticking out of the end gives you something to get mole grips on when you next have to change it ;)
Click to expand...

Bad idea, unless you have excess shaft length between the end of the bearing and the prop. The space (usually around 15mm) is for the water to flow in and out.

Anyway with a removable bearing housing like this no problem to press it out - don't need to use mole grips.
 
nedmin said:
Just to confuse the issue ,it is possible to have a mixture of imperial and metric on the same cutless,my last boat had a 40mm shaft and the cutless outer was imperial ! If you have room between the prop and cutless leave about 3/8th of an inch of the cutless stuck out.but before you do that drill 2- 1/4 inch holes diagonally opposite,try not to cut thro, the rubber, then you can make an extractor with 2- 1/4 pins in to remove the cutless,using the prop shaft centre screw hole to put the extractor screw in.Obviously you do not want to put to much tension on the flexible coupling. Works well for me but i do put silicon grease on the cutless before installing .
Click to expand...

Or you could bed the bearing on epoxy, removal involves some heat to soften the epoxy, no pullers or presses required. As a clearance fit you can also check carrier alignment, chock shaft and have a dry run, the bearing should be able to spin on the shaft in the carrier. You can have the ID and OD made to suit your boat so as long as it is measured accurately the size is not an issue.
 
There comes a time when you have to admit that you simply haven't got the experience for a job like this. Engineers have.
 
oldvarnish said:
There comes a time when you have to admit that you simply haven't got the experience for a job like this. Engineers have.
Click to expand...

That's why I'm letting Crowthers do it.
£60 to supply and fit the cutlass bearing to the housing sounds good to me.

Also need a new prop and prop shaft so will hopefully get a good deal for it all.

Also can't leave any sticking out as the rope cutter would get in the way.

Rob
 
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If the old bearing looked like solid rubber bonded inside the bronze fitting it sounds like the one I had. I had all sorts of expensive solutions proposed to me but a quick phone call to Countrose Bearings in Birmingham with the dimensions revealed that it was an old Stuart Turner bearing. they were able to supply me with a suitable replacement (rubber in a phenolic shell) from stock next day for about £34 which was a simple press in fit. Two years later and it's still in good condition.

Incidentally the guy at Countrose said that there is starting to be a steady demand for these bearings as the originals are starting to fail after about 30-40 years!!

I don't have the phone number to hand but just google it. Countrose make a lot of the cutless bearings that others sell at inflated prices.

John

p.s. this particular bearing was not on their list at the time,w hich was why nobody else could identified it.
 
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