Replacement Cutless Bearing - What type?

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Got the original Jeanneau one out this weekend but had to finally saw a section out to enable its removal. Trying pressure just made the outer plastic housing deform locally.

The original Jeanneau bearing was in a hard white plastic outer housing bonded to what appeared to be a thin tube of possibly phospher bronze and finally a inner cylinder of a black hard rubber substance with longitudinal grooves (I assume to enable water to lubricate/cool the bearing) as the bearing surface against the shaft.

The bearing is for a 30mm shaft and 200mm long.

I was concerned over the difficulty of pressing in a new plastic bearing and understand that many replace these with a complete phospher bronze bearing.

Can someone advise how these are different please? do they still have longitudinal grooves?
 
Re: Replacement Cuttless Bearing - What type?

The correct description of the bearing is a 'cutless rubber bearing'. The rubber part is your black inner with longitudinal grooves. It is usually a nitrile rubber, although other compositions can be used. This is bonded into a carrier that may be a bronze or a phenolic resin. Sounds like yours is a further variation of this. Measure the bore of the housing, diameter of the shaft and the length of the bearing and get yourself down to your local chandler, or look on line for cutless bearings.

I've never seen one with an outer plastic sleeve. The only time I know of this type is to prevent recycling of electric currents, which seems pretty unlikely in an underwater bearing!

Despite what it says in the link posted above while I posted mine, the correct spelling is 'cutless', not 'cutlass', one of the most frequently misspelt words in yachting.
 
Re: Replacement Cuttless Bearing - What type?

'cutless', not 'cutlass', one of the most frequently misspelt words in yachting.

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Absolutely correct although I got sick of saying so on this forum about 2 years ago!

To add to what you said, the original patented Cutless bearings always had a Phosphor Bronze outer sleeve. There have been many ersatz copies and replacements since then though and some cheapies do in fact have moulded plastic outer sleeves. Best avoided IMHO. There is only one replacement I would fit other than a genuine Cutless and that is one (sorry name escapes me) that looks very similar but it is urethane rather than nitrile rubber and resists wear better. Still has a bronze outer sleeve though!
 
Re: Replacement Cuttless Bearing - What type?

I normally have no problem buying from ASAP supplies but as they can not only not spell Cutless, but say they are made of NAVEL Brass /forums/images/graemlins/laugh.gif perhaps not in this instance!
 
Thanks. Spelling corrected!

I think my problem is with the hard white plastic shell. The bearing would not slide out using a made up press arrangements and one person advises not to replace with the original plastic one as the plastic "binds" and is difficult to insert without damage.

Do you have any preference in material choice. From ASAP website they all appear to be grooved Nitrile rubber inside so at least I understand about that bit now!
 
I fully agree with Boatmike. I always fit the type with a bronze sleeve. I have tried a phenolic resin one but it didn't seem like a proper engineering job to me so I went back to a bronze one.

My problem with the phenolic ones was that the resin swells when it gets into the water, so they are made with excessive clearance when first fitted. This takes up after a while but there is always an element of estimation with the product. Mine seemed extremely tight after a couple of weeks and the shaft subsequently suffered some wear, possibly associated with the lack of clearance.
 
The phenolic plastic ones are hydroscopic = swell in water. IMHO always use the bronze shelled ones. I am suspicious of the ASAP ones because "Naval Brass" can mean anything frankly. If they are DZB which I suspect they are they are probably OK as the shell is completely encased when installed (apart from very ends) But I would tend to use plenty of waterproof grease when installing.
 
I had the same advice for the bearing on my Jeanneau. I fitted a bronze shell bearing with no difficulty and dont expect it to be difficult to remove, based on experience of other boats.

Plus it was 60% of the price Mr Jeanneau wanted!
 
Depends where you use it. Muddy estuaries are very hard on them, drying moorings may be too. Canal du Midi did mine no good at all - worn out in one year. In North Wales, deep, clear water, I kept the same one for years.
 
Varies a lot, on my 336 I replaced early at 9 years, it could have done another season or two.

On 38 replaced after 4 years.

not sure you can talk averages as variables include
- Usage
- anything gets around the prop
- engine mounts lose or soft allowing torgue
- engine alighnment
- fouling preventing water through the bearing
- some variable pitch props can put additional tension
- rope cutters going through nasties
etc etc
 
Yes, I was more than a bit surprised /forums/images/graemlins/mad.gif

We will see how the bronze shell lasts.

I would expect 4 to 5 years, but as Pete says it all depends.
 
My father has a 1982 Jeaneau Espace 1000.

He replaced the cutless bearing in about 1990 for one with a plastic outer.

That was replaced in 2003 for a Jeaneau metal outer one (£90).

It's just been replacad again when the propshaft was replaced, the new propshaft cost ouch£££££££s.

It's used West Scotland.
 
[ QUOTE ]
I fully agree with Boatmike. I always fit the type with a bronze sleeve. I have tried a phenolic resin one but it didn't seem like a proper engineering job to me so I went back to a bronze one.

My problem with the phenolic ones was that the resin swells when it gets into the water, so they are made with excessive clearance when first fitted. This takes up after a while but there is always an element of estimation with the product. Mine seemed extremely tight after a couple of weeks and the shaft subsequently suffered some wear, possibly associated with the lack of clearance.

[/ QUOTE ]

Just to mention that the marine engineers in the marina said to me that the Nitrile inner swells too.

Thanks to this forum I have switched over from a white metal bearing ( cost £215 ) to a brass/nitrile costing about £30. The white metal bearing lasted about 5 years (muddy East Coast).

I now take the view that my bearing is a consumable and I am happy to replace about every three years. Fortunately, mine is very easy to get at and replace.
 
Another vote and agreement that bronze is better than resin.

Had a resin one once that came with boat and not wanting to draw the shaft had to melt out the rubber, then carefully cut the resin shell with juinor hacksaw blade and tap out . Not a quick job.

However last week changed my bronze bearing inc taking prop off and on in during the hoists lunch hour.

You can get special under sized bearings to take into account shaft weardown from Countrose who are UK maker ( or at least you could when they were in Leeds, not sure if they still do this offer now they have moved to Birmingham)


Brian
 
I just want to add some detail as phenolic was mentioned in a shell context, it is also available as a bearing material.

Composite bearings have been used to replace rubber cutless bearings in some very high performance vessels. They run close tolerances and hold the drive in alignment from start up. They can also be made with lower dry friction than teflon to limit wear in the start up dry phase before water is supporting the shaft.

We also don't press fit if it can be avoided.

The comments on swelling and clearance are vastly different for each brand, as each phenolic bearing or shell is a composite of many materials with each manufacturer using their own recipe.

Rubber in bronze shell is ideal for most applications, but phenolic resin bearings are actually an improvement over rubber in most, if not all cases. If the ships we supplied had a cutless bearing run tight we would probably be asked to cough up for the dry dock fees!

Bedding a bearing on epoxy is also a good check of alignment, as you can only spin the bearing in the carrier on the shaft if the two are aligned.
 
Thanks for all this info its really useful. I have a Jeaneau SO 36i on the Hamble and the cutless bearing has gone after only 9mths. Its under warranty so I have the dealer now looking at engine alignment etc. Sounds to me like this is not normal. Any thoughts?
The Prop was pretty scaled up too, in case that has contributed any advice on how to stop that happening too??
Thanks
Kate
 
Replacement Cutless Bearing - How often?

Mine does about 1200-1500 hours, but it's minute, 70mm long and for a 25mm shaft. Operates at between 1000 - 1800 rpm (seldom the upper).

Phenolic-outer bearings appear to be the longest lived.

The most critical factor in bearing wear is how well the shaft is aligned.
 
Hi Kate,

Out of balance or out of alignment are the usual causes of excessive bearing wear. Slightly damaged prop or debris around the prop for a while can vibrate the shaft, if you also have sandy or silt laden water this just adds to the wear.

To get the best out of shafts and bearings a great degree of precission is needed, but in most yachts as the power is quite low and shaft speeds are also usually low you can get away with some inaccuracies.
 
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