Cutless bearings don't seem to last very long in the med

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SlowlyButSurely

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Since we've been in the med we seem to need to change our cutless bearing every year whereas back in the UK it would last about 5 years. Also the prop shaft accummulates a build up of limescale.

Has anybody else experienced this?
 
Cant comment on the med but there is a chap on here ( name escapes for the moment but he might rspond to your post) who flogs cutlass bearings made of something totally different to the normal rubber jobbies. I have one and its lasting way way better than anything I have had before.

Yes I know thats no immediate help, but hopefully he will be along soon.

P.S. Quick look at my bookmarks. I'm fairly sure it was https://www.countrose.com/content/standard_sizes.asp
 
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Ours is fine after 5 years in the med (Touch wood of course!)
Your exact location could be more important than just being in the Med.
Some marinas have particularly bad water quality like for example a marina in Cagliari which was practically stagnant with very low oxygen levels and increased risks of corrosion to some SS componants
 
I think there may be another reason rather than your location. I installed my cutless bearing in south east France when I fitted my new P-bracket (see on the website) in 2005. Since then we have been exclusively in the Mediterranean, on the water for half of most years, now in the Aegean for the past 9-10 years. My cutless bearing remains in good condition. In that time the engine has run almost exactly 2000 hours.
 
SlowlyButSurely said:
Since we've been in the med we seem to need to change our cutless bearing every year whereas back in the UK it would last about 5 years. Also the prop shaft accummulates a build up of limescale.

Has anybody else experienced this?
Click to expand...

Maybe due to over-protection by anodes.
The pH at the surface of the cathode tends to increase. If this is excessive it can lead to a build up of scale.

What anodes do you have ( Prop anodes, shaft anode hull anode ) or what type ( Zn or Al) ?
 
Ours haven't been lasting very long due in part to the Vetus ones being oversize I.D and buildup of scale. Have a Countrose bearing to fit next winter with harder compound. One of the club's racing boats needs annual cutless change as it does very little time on engine and the scale destroys the bearing and I suspect that's part of our problem.

Interesting comment above about anodes, the only places we get barnacles are the shaft, P bracket and bottom rudder hinge, all of which are bonded. Unbonded keel and hull virtually clear.
 
Graham376 said:
Ours haven't been lasting very long due in part to the Vetus ones being oversize I.D and buildup of scale. Have a Countrose bearing to fit next winter with harder compound. One of the club's racing boats needs annual cutless change as it does very little time on engine and the scale destroys the bearing and I suspect that's part of our problem.

Interesting comment above about anodes, the only places we get barnacles are the shaft, P bracket and bottom rudder hinge, all of which are bonded. Unbonded keel and hull virtually clear.
Click to expand...

I think this could be the problem because we switched to Vetus just before leaving the UK. Prior to that we were using Aqualube cutless bearings but to be honest I never really gave the brand any thought, just bought them from T Norris who supplied the stern gear. The Vetus bearings came from ASAP along with a whole load of other spares we ordered before we left. I will order a Countrose bearing for next year.

The anode idea is worth further investigation. It's a steel boat and we have 4 x 4kg hull anodes plus 2 on the rudder and one on the rudder stock. It's a long keeler so the shaft is entirely inside the stern tube except for about one inch behind the cutless bearing.

Thanks very much for all the replies chaps.
 
Limescale, if thats what it really is, is a carbonate. Its a long time since I did inorganic chemistry but I cannot think of a way that electrolytic action would deposit that on a stainless shaft. So forget anodes.

Is your toilet / holding tank outlet near the shaft? You get deposits in the toilet piping because of pee so maybe the shaft too? But more likely its just tiny creatures starting to deposit shell material.

Reference my earlier post I sail mostly in the Britol channel where there is so much sand and clay in the water that it looks like milky coffee and works as a sort of fine abrasive. The bearings I linked to have been outstanding in resisting wear whereas the old rubber ones gave maybe 2 years at most.
 
birdseye said:
Limescale, if thats what it really is, is a carbonate. Its a long time since I did inorganic chemistry but I cannot think of a way that electrolytic action would deposit that on a stainless shaft. So forget anodes.

.
Click to expand...

I can though.
Cations in solution in the electrochemical cell migrate to the cathode surface. (The shaft in the case of a sacrificial anode on a stainless steel shaft.)
The reactions which occur at the cathode surface result in a localised increase in pH.
The increased pH can result in the deposition of calcium and magnesium carbonates from water high in temporary ( bicarbonate) hardness in much the same way that "limescale" deposits can be formed in the outlet pipework of marine toilets
A similar rise in pH can cause electrochemical decay of wooden hulls
 
VicS said:
I can though.
Cations in solution in the electrochemical cell migrate to the cathode surface. (The shaft in the case of a sacrificial anode on a stainless steel shaft.)
The reactions which occur at the cathode surface result in a localised increase in pH.
The increased pH can result in the deposition of calcium and magnesium carbonates from water high in temporary ( bicarbonate) hardness in much the same way that "limescale" deposits can be formed in the outlet pipework of marine toilets
A similar rise in pH can cause electrochemical decay of wooden hulls
Click to expand...

Umm... thanks Vic...

To illustrate...



Heavy deposit of limescale on stainless prop shaft, shot anode, shot cutless bearing, all in the one picture. And I’m coming to this from fifty years of wooden boats where I had learned to ban anodes...
 
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