New yachts rudder bearing failures

[geem]

We met a lovely couple who came over to the Caribbean on the 2018 ARC they have a Jeanneau 54 that is still in warranty. Apparently they have warranty work needed. The rudder bearings need replacing! They said all the Atlantic down wind sailing was hard on the bearings! I may be wrong but I would have thought that was the least load on rudder bearings. He also said that lots of boats had rudder bearing issues following the ARC. Since most boats on the ARC in 2018 were less than three years old, what is going on with these modern boats and rudder design? I cant imagine buying a new boat and having rudder bearings issues in such a short space of time

 

[vyv_cox]

Were these all rolling element bearings? There seems to be a trend to fit them now, especially on larger boats where they will reduce friction compared with a plain bearing. However, rolling element bearings are not very long-lasting in oscillation and this may be the cause of the problems. Bearings with cages are more susceptible but angular contact types with cages accept axial thrust and are probably the type selected.

 

[Neil_Y]

Rudder bearings get a pretty hard time sailing downwind in any waves, as the steering movement is greater and the loads higher as you try to stop the boat being pushed off course from the following waves and it's constant for 20 days or more. So 480 hours of wear at quite high loads is probably more than many boats will see over a couple of years of weekend sailing. We also saw a boat where the hull had cracked around the rudder bearing which was brand new so the owners were looking at warranty repairs.

The thing is there are now far better materials than Delrin as a plain bush and rolling element bearings have their downsides. It would be interesting to know what types of rudder bearing had issues.

 

[lw395]

A lot of yachts, it seems to me the autopilot is on a mission to wear out the bearings, needlessly sawing the wheel from side to side?

 

[sarabande]

There is a not uncommon cause of roller bearing failure called "brinelling" where instead of a rotary load, there is a side to side linear load which causes the balls to make dents in the bearing races. This can set off corrosion , distortion, spalling leading to bearing seizure or other failure.

The rolling motion of a boat going downwind may generate alternating lateral loads on the rudder and transfer these to the stock and bearings.

 

[Graham376]

Would be interesting to know if all the failures are on spade rudders. Don't understand the explanation about bearing failures above, vehicles go tens of thousands of miles with much higher stress on wheel bearings which can be either ball or roller.

 

[geem]

Rudder bearings get a pretty hard time sailing downwind in any waves, as the steering movement is greater and the loads higher as you try to stop the boat being pushed off course from the following waves and it's constant for 20 days or more. So 480 hours of wear at quite high loads is probably more than many boats will see over a couple of years of weekend sailing. We also saw a boat where the hull had cracked around the rudder bearing which was brand new so the owners were looking at warranty repairs.

The thing is there are now far better materials than Delrin as a plain bush and rolling element bearings have their downsides. It would be interesting to know what types of rudder bearing had issues.

I have no idea what kind of bearings are installed in modern production boats but surely a single Atlantic crossing should not be enough to wear the bearings out? It sounds like it was a common problem. Are modern 54 ft production boats built for just weekend sailing?

 

[geem]

Would be interesting to know if all the failures are on spade rudders. Don't understand the explanation about bearing failures above, vehicles go tens of thousands of miles with much higher stress on wheel bearings which can be either ball or roller.

I think most modern production boats these days use spade rudders. The loads on the bearings must be considerably more than those rudders mounted on skegs.

 

[Graham376]

Are modern 54 ft production boats built for just weekend sailing?

In theory no but, accountants are too involved with reducing production costs these days and spade rudders much cheaper to build than a decently supported skeg.

 

[dunedin]

Was on ARC 2018 and didn't hear any chat on the dock at St Lucia about a lot of rudder bearing issues. Ripped sails yes. Rudder bearings not convinced- though a few older boats did have a couple of unrelated failures.
Plenty of wheel twiddling in 3000 miles quite fast downwind though

 

[Baggywrinkle]

All part of the process of learning ... someone, or more probably, some design team, have made a decision to use a particular construction method that is proving to be troublesome. I guess it will go the way of all other sub-standard designs and be rectified in future models.

This has always been the case, even the beloved Contessa 32 in earlier versions was criticised for weak shroud plates, under-sized rigging and hull stiffening in the forward heads was inadequate and required modification.

We live and learn - and nothing focusses the minds of the manufacturers like warranty claims and bad publicity.

 

[lw395]

All part of the process of learning ... someone, or more probably, some design team, have made a decision to use a particular construction method that is proving to be troublesome. I guess it will go the way of all other sub-standard designs and be rectified in future models.

This has always been the case, even the beloved Contessa 32 in earlier versions was criticised for weak shroud plates, under-sized rigging and hull stiffening in the forward heads was inadequate and required modification.

We live and learn - and nothing focusses the minds of the manufacturers like warranty claims and bad publicity.

Exactly.
The yacht industry does not have prototypes of every model going through the equivalent of the several 100,000 miles new car models are put through.
Owners of new models are the beta testers.

Just how widespread were the problems anyway?

 

[geem]

All part of the process of learning ... someone, or more probably, some design team, have made a decision to use a particular construction method that is proving to be troublesome. I guess it will go the way of all other sub-standard designs and be rectified in future models.

This has always been the case, even the beloved Contessa 32 in earlier versions was criticised for weak shroud plates, under-sized rigging and hull stiffening in the forward heads was inadequate and required modification.

We live and learn - and nothing focusses the minds of the manufacturers like warranty claims and bad publicity.

The Contessa32 was developed in an era of super low investment and small boat production runs. I dont think that can be compared to a manufacturer like Jeanneau who have built thousands of boats. My understanding also, is that this high bearing attrition rate wasnt just a single manufacturer but a common problem amongst production boats less than three years old

 

[vyv_cox]

Would be interesting to know if all the failures are on spade rudders. Don't understand the explanation about bearing failures above, vehicles go tens of thousands of miles with much higher stress on wheel bearings which can be either ball or roller.

Bearings that constantly rotate, if well lubricated and kept free of dirt, will last indefinitely according to SKF. The example of false brinelling shown above occurs when bearings are subjected to vibrations of very small amplitudes, up to around 20 microns. Bearings that are in an oscillating duty do not suffer false brinelling but they are very difficult to lubricate and can wear surprisingly quickly.

 

[Just_sayin']

He also said that lots of boats had rudder bearing issues following the ARC.

I know of three boats that set off last year specifically on the ARC. One of the older ones returned due to battery issues. The other two modern boats made it safely.

I know of three other boats that are variously starting to or actually circling the globe. Two modern, one classic.

We keep in touch. I’ve asked the question regarding these mass failings.

Three replies so far.

No mass failures of bearings either experienced or heard of.

No reports on the ARC site

No mention of it on other forums I follow.

Apparently totally missed by the worlds yachting press.

Unless someone could point to a source.

We’ve done the ARC three times and you get to hear about failures en route or upon arrival.

Most are what you would expect but there was no one particular problem that stuck out.

Looking forward to some links.

 

[Baggywrinkle]

The Contessa32 was developed in an era of super low investment and small boat production runs. I dont think that can be compared to a manufacturer like Jeanneau who have built thousands of boats. My understanding also, is that this high bearing attrition rate wasnt just a single manufacturer but a common problem amongst production boats less than three years old

You can invest millions and still not catch every problem .... the point being that until a technology is deployed in a certain application, any predictions of longevity, suitability etc. are just theoretical. If I was a betting man, I would bet the yacht manufacturers went looking for a supplier of better rudder bearings (as the boats got bigger and the rudders more unwieldy) and got sold a dud by a bearing company that didn't fully understand the application. I see it all the time at work, all the normal use-cases and scenarios get thought about, but some corner cases slip through or are argued back and forwards 'till he who shouts loudest wins. It's always a matter of opinion until you have a warranty bill to back you up - by then it's too late and "I told you so" has limited use. .... add to this the situation where suppliers (or rather their sales force) will promise the world to win a contract.

I would expect the boat builders to know all about the forces on the rudder stocks, but I would not expect them to be experts on bearing technology - that's what bearing manufacturers bring to the table. You could argue that the yacht manufacturers made a poor technology or supplier choice, but such is life - s**t happens.

 

[Neil_Y]

Exactly.
The yacht industry does not have prototypes of every model going through the equivalent of the several 100,000 miles new car models are put through.

True but if you want to supply bearings that are approved by Lloyds you have to carry out a rudder simulation test for 1000hours. Increasing loads every 200 hours on a simulation rig in the lab.

Highest load we tested to was final 200hours at 20Mpa or around 2900PSI. The test was designed to show wear rates of rudder shaft and bearing run dry. Our results showed no measurable wear on rudder or bearing.

I'd like to know the source of this report/information as it hasn't been picked up by the press?

 

[FlyingGoose]

I know of three boats that set off last year specifically on the ARC. One of the older ones returned due to battery issues. The other two modern boats made it safely.

I know of three other boats that are variously starting to or actually circling the globe. Two modern, one classic.

We keep in touch. I’ve asked the question regarding these mass failings.

Three replies so far.

No mass failures of bearings either experienced or heard of.

No reports on the ARC site

No mention of it on other forums I follow.

Apparently totally missed by the worlds yachting press.

Unless someone could point to a source.

We’ve done the ARC three times and you get to hear about failures en route or upon arrival.

Most are what you would expect but there was no one particular problem that stuck out.

Looking forward to some links.

Have to agree , the OP has not stated any factual proof rather a hear say from one person who then goes onto to say loads of others have suffered the same fate (loads = what number) then op tells us that out of the 200+ boats that sail the ARC most are under 3 years old
now I have seen a lot of ARCs and there are plenty of Cats in there , racing boats competing for the fastest time, and the usual cruisers
so I cannot take anything seriously from an old sea dog at the bar telling their stories until there is proven fact
As JS Posted no magazine coverage , no ARC safety announcements no nothing in fact but gossip , but we all know gossip to be true that why we listen to it and write about it on these forums
Maybe Geem your are slightly biased to new boats as you have previously vocalised on many other threads

 

[rogerthebodger]

The SKF design bearing calculation is based on 90% life of bearings

Basic rating life
For simplified calculations and to obtain an
approximate value of the bearing life, the so-called “handbook method” is used to calculate the basic rating life. The basic
rating life of a bearing according to ISO 281

Life 10 = (C/P) to the power of p


where
L10 = basic rating life (at 90% reliability), millions of revolutions
C = basic dynamic load rating, kN
P = equivalent dynamic bearing load, kN
p = exponent for the life equation
= 3 for ball bearings
= 10/3 for roller bearings, as used
typically in axlebox applications
The basic rating life for a specific bearing is
based on the basic dynamic load rating
according to ISO 281. The equivalent
bearing load has to be calculated based on
the bearing loads acting on the bearing via
the wheelset journal and the axlebox
housing.

Plain bushe life is based on a PV value (Bush pressure and bush surface velocity)

The PV valve is compared to the PV for the bush material obtained from the bush supplier.

I use vesconite whos bush design manual is here

https://www.vesconite.com/wp-content/uploads/2016/12/vesconite-marine-design-manaul.pdf

 

[Skylark]

Maybe Geem your are slightly biased to new boats as you have previously vocalised on many other threads

I don’t believe that he’s “slightly biased” based upon his comments in many others threads.

Exceptionally biased to the point of obsession would be a more accurate description

Still, if writing anti AWB trolls makes him happy, who are we to judge.