Cutlass Bearings - when to replace?

[Illusion]

Hi,

Just wondered if anyone had any experience of when and how you tell these need to be replaced? Assume it would be a result of vibration, or travel in the bearings when you try and move the props and shafts.....but the question is how much movement is acceptable, as we don't have any vibrations and being told they need to be replaced?

The boat has now completed 7 seasons of use and circa 470 hours and to my knowledge they're still the original set.

Thanks

Phil

 

[sarabande]

cutless bearing is to prevent vertical and lateral movement; horizontal movement along the shaft will be down to the thrust bearing and/or engine bearings.

How much movement in the cutless do you have ? If everything was perfectly set up initially, and the (water) lubrication is fine, then best leave alone.

Some people reckon on a ten year life.

http://www.bmse.co.uk/articles/article5/

 

[jfm]

They need replacing if there is more than a couple of mm sideways movement but 470 hours seems low. I'd expect around 1000 hours in clean water (Med). But depends more on how silty the water is than the hours count so in UK S coast and solent I guess 470 is just about plausible. It's not a big deal to change them. Are they proposing to change both ends or just the P bracket bearings?

 

[Nick_H]

I'm on 1250 hrs and haven't yet replaced the bearings. I checked them at haul out recently and there's no play, and there's also no vibration underway, so I plan to leave them a few more years. That's in nice clear med water though, and probably 300 of those hours are at displacement speed.

 

[Tranona]

Ask the yard to explain to you why they need replacing, including if necessary demonstrating that there is indeed wear.

 

[Hurricane]

When replacing them, would you replace the hull and the P bracket bearings?
If so, that would also mean (probably) mean replacing or repacking the glands - in my case replacing working glands and the spare ones upstream on the shaft.

I checked my bearings a couple of weeks ago - no play after 8 years and about 850 hours.

 

[kashurst]

I replaced mine at 1100 hours. No problem going forwards but a distinct rumble in reverse. they had about 3mm -4mm play - so well past their best. At 470 hours I would get a second opinion.

 

[NoIllusion]

Hi,

Just wondered if anyone had any experience of when and how you tell these need to be replaced? Assume it would be a result of vibration, or travel in the bearings when you try and move the props and shafts.....but the question is how much movement is acceptable, as we don't have any vibrations and being told they need to be replaced?

The boat has now completed 7 seasons of use and circa 470 hours and to my knowledge they're still the original set.

Thanks

Phil

Replaced ours 2 weeks ago. Boat has done 460 hours. Only needed to replace P bracket bearings. I guess there was around 1-2mm play in them. No noticeable vibration but thought it best to get them replaced. Boat is nearly 10 years old.

 

[Illusion]

Thanks for all the input.
Decided in the end to pop down to the boat and take a look myself. Seemingly there is some play, difficult to judge but I would guess 2-3mm? At the moment it just looks like the p-bracket bearings that need replacing but the inboard end will also be checked.
On reflection seems it's worth just biting the bullet and getting them replaced, should hopefully give us peace of mind for a few more years.

Appreciate all the views and first hand experience.

 

[chrishelen]

I run a small commercial motor boat, I put a new cutless bearing in this time last year, I could move the 1inch prop shaft 2-3mm. I do around 3000hrs a year, on lift out last week there was no play in the bearing, gearbox alignment and engine mount condition are key here.

 

[Bandit]

The view on max play is about 1.5mm.

As well as silt or sand catgut will damage the rubber of cutless bearings by spinning on the shaft like a scouring pad and rope will damage cutless bearings by blocking the waterflow and then the cutless bearings will overheat. I saw a large mobo where the rope had melted and set between the prop and p bracket and the rubber of the cutless bearing was burnt and destroyed.

Look for :
Play in any direction when you move the shaft.
Uneven wear of a cutless bearing may be due to poor alignment.
Damage to the rubber at the prop end.
The rubber slipping out of the p bracket, it might be a few mm or lots.