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Old 17-06-2016, 19:17   #16
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Re: Lubricant for rudder bearings

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Hi Paul,

That's not correct, there is no bending of the rudder shaft. The wall thickness is nearly an inch on the shafts constructed of carbon fiber, and the load is carried top and bottom. If there were bending happening, it would be apparent at the lip seal at the top of the stern tubes. It's just not happening.

I've been down there watching the shafts with the boat doing 12-14 knots, and it's rock solid, no deflection. The lip seals are basically right at the middle of the point between bearings, so it would be obvious.

As I mentioned, the rudders are designed to provide lift to a degree not found in conventional rudders, so high speed reaching generates a lot of side force. I'm 100% sure it's friction in the lower bearing.

Thanks for the suggestion, though.

TJ
TJ
Does the steering loading come on slowly or isit really only when the rudder is heavily loaded.
I put in a Jefa GRP-PETP composite bearing on my CF shaft with a stainless sleeve over the shaft in contact with the roller bearings. No detectable additional friction when the rudder loads up, but I suspect yours has higher loads.
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Old 17-06-2016, 19:18   #17
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Re: Lubricant for rudder bearings

Forespar's LanoCote is a lanolin grease meant for marine applications. While a grease consistency, you can soften it all the way to a liquid by leaving it in the sun or putting the plastic tub in a pan of hot water.

LanoCoteŽ Lubricants & Coatings

Another option is Forespar Marelube that is designed to lubricate seacocks. It is used on the Marelon plastic seacocks as well as metal. A synthetic grease but no petroleum

MareLube™ Lubricants

I've carried both products aboard for years.
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Old 17-06-2016, 19:28   #18
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Re: Lubricant for rudder bearings

Jim,

I wish I had a picture of these bearings, it would be much simpler, in essence, the stainless part which sits on the rudder shaft is shaped like a bit like a donut, and the carbon socket it rides against has an outer diameter that fits in the rudder tube.

So, we have SS sliding on carbon, maybe 24 square inches of total bearing surface.

McLube had also occurred to me. I think we'll go with that.

Your points are well taken on the insignificance of petroleum lubes in this application regarding environmental impact. I wasn't really making my environmental stand in my rudder tubes, but if there was something somebody could think of that would fit the bill and still be non-petrol, well, so much the better.

Thanks to everyone for the input. Time to dig into the lazarette and get going. Thanks also for the good wishes on the passage. We're going from Charleston to the Canadian maritimes then to the UK, departing from St. John's, NFLD. in late July/early August. Hopefully the weather gods are kind to us.

TJ
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Old 17-06-2016, 19:39   #19
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Re: Lubricant for rudder bearings

I like McLube a lot but I think it would wash out quite quickly in this application.

.
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Old 17-06-2016, 19:43   #20
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Re: Lubricant for rudder bearings

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Originally Posted by Paul L View Post
TJ
Does the steering loading come on slowly or isit really only when the rudder is heavily loaded.
I put in a Jefa GRP-PETP composite bearing on my CF shaft with a stainless sleeve over the shaft in contact with the roller bearings. No detectable additional friction when the rudder loads up, but I suspect yours has higher loads.
Paul,

It generally gets stiff when there's a puff and the boat heels over hard and then also slides down the side of a wave while reaching. Exactly when you'd expect the side loading to be the greatest. When we're hand steering, you can really feel it, and once the 'slide' is over, everything's jake again. We just hold a bit of pressure on the wheel, and then it will let go once that condition has eased.

It only happens when reaching fast.

The main issue is when we're using the pilot. When it tries to correct against this condition, in the worst case, we get an overamperage alarm and it cuts out.

I think that we just really need to get some Jefa style roller bearings and all will be just fine. The SS/CF surface with no rolling surface just isn't the best. I think it creates too much friction under load.

It's not terrible, but it's not ideal either. Obviously, the boat's done just fine with this arrangement over the years.

I just hope we can find somebody we can send one of our bearings to, and they can fabricate the same specs, but in a roller bearing. Maybe I should contact Jefa. I don't know if they've got the tooling for a custom set of bearings, but I suspect they might.

A project for the next pit-stop, which we'll do in the UK this winter. In the meantime, we'll mclube it and call it good.

TJ
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Old 17-06-2016, 19:47   #21
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Re: Lubricant for rudder bearings

Carl,

Thanks for the tips. Maybe I'll spray some mclube down there first, and then dump some of the liquid marelube in for good measure!

TJ
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Old 17-06-2016, 20:01   #22
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Re: Lubricant for rudder bearings

Second the mercruiser extreme grease. I was confirming tech specs for grease on my own rudder system and this is a very water resistant grease that doesn't lose its thickened qualities in a wide temperature range.

I'm away from my computer and can't remember details. The basic specs can be met by a wide range of brands.




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Old 17-06-2016, 20:11   #23
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Re: Lubricant for rudder bearings

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Hello forum,

We are getting ready for a long passage, and I would like to get some lubrication into our lower rudder bearings.

The bearings are similar to the 'Jefa' units in construction, but different materials.

The 'outer race' of the bearing is carbon fiber, and the 'inner race' is an oblate sphere made out of stainless. The bearings are not in the water when the boat is flat, but are submerged when heeled. (we have twin rudders)

I've noticed that when reaching in strong conditions, the wheel gets stiff when the rudder has a lot of side load. I would like to find some kind of a spray that I can pop the seal off at the top of the rudder tube, spray said (eco friendly) lube in, and reinstall the top seal. removing the rudders is not an option before leaving.

Any ideas? Something with Teflon? It needs to be at least somewhat waterproof, and since they're under water some of the time, We don't want any petroleum in there.

Thanks for the ideas. TJ
Lubricating a non metallic bearing with a lubricant is a recipe for disaster. Typically structural plastics require no lube. If its wet when heeled then it should be designed to be wet. Any lube will dissapear pretty quick when wet.

Plastic bearings can be kept cool with water, which has good heat transfer properties, but water is a poor lubricant.

A wd40 type lube (any mineral based lube) will carry any particles and turn the resultant suspension into an abrasive slurry.

If your rudder is getting stiff under load then i'd be concerned about deflection improperly loading my bearings.

Eco friendly lubes (never seen one in 30 years) will not have suitable properties as a lubricant.

What does the manufacturer suggest?

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Old 17-06-2016, 20:28   #24
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Re: Lubricant for rudder bearings

Hello, nobody knows who made the bearing.

I'd like to state again, I'm 100% sure that there is no deflection, and even if there was, the way the bearing is constructed, some misalignment or deflection will not have any impact on the operation of the bearing. I would say that the rudder shaft could bend up to 10 degrees of arc before bearing performance was compromised.

Carbon fiber does not bend like that. It would fail long before it reached anywhere near the deflection needed to compromise bearing function.

I wish I had a picture, then we wouldn't have to keep having the 'deflection/misalignment' conversation. The rudders are massively overbuilt carbon structures, designed to survive a heavy impact due to their location on the boat. These things simply are not down there flexing. The bearings are fairly new in their installations, as well. Wear is not a factor.

Also, note that 1/2 of this equation is stainless steel. The other half is carbon fiber. Does that make it a non-metallic bearing? I don't know.

I'm really, really, absolutely, positively sure that this is simply an issue of the stainless inner race pressing hard enough on the carbon outer race that it is creating friction during the heaviest part of the load cycle in a very limited set of sailing conditions. Hence the plan to replace these with roller bearings at the next haul. In the meantime, I wish to lubricate them with something to help out with this small issue.

So, I guess that my question is, considering the materials involved, am I actually going to destroy carbon fiber with any type of lubricant?

Thanks, I don't mean to be snippy, but this same thing keeps coming up, and it's just not happening that way.

Insight into lubricants destroying carbon would be appreciated, however.

TJ
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Old 17-06-2016, 21:58   #25
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Re: Lubricant for rudder bearings

TJ
Jefa will do custom maching of their nearing for reasonable cost.

Hope you have a good passage
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Old 17-06-2016, 22:30   #26
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Re: Lubricant for rudder bearings

Not sure it helps, but there are a fair number of conversations about greasing carbon fibre on the biking boards. They are as inconclusive as the sailing boards.
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Old 18-06-2016, 17:01   #27
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Re: Lubricant for rudder bearings

You can get Lanolin in the form of heavy lanoline grease from most auto-shops. Ypu can also buy it from a drugstore but you need to get PURE stuff--which is a heavy grease not mixed with soap or detergent to soften it and make it spreadable.

You could heat it and mix in some graphite or some other high efficiency molybdenum compound. That would make it better--but the lanoline will stick to most surfaces quite well. I have used it for a variety of purposes in the past--it is under-rated.



This will give you a grease that might work for a while. Lanoline is WATERPROOF unless it has been emulsified it with detergent or soap. Maybe you can buy it online.
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Old 18-06-2016, 17:21   #28
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Re: Lubricant for rudder bearings

Quote:
Originally Posted by TJ D View Post
Hello, nobody knows who made the bearing.

I'd like to state again, I'm 100% sure that there is no deflection, and even if there was, the way the bearing is constructed, some misalignment or deflection will not have any impact on the operation of the bearing. I would say that the rudder shaft could bend up to 10 degrees of arc before bearing performance was compromised.

Carbon fiber does not bend like that. It would fail long before it reached anywhere near the deflection needed to compromise bearing function.

I wish I had a picture, then we wouldn't have to keep having the 'deflection/misalignment' conversation. The rudders are massively overbuilt carbon structures, designed to survive a heavy impact due to their location on the boat. These things simply are not down there flexing. The bearings are fairly new in their installations, as well. Wear is not a factor.

Also, note that 1/2 of this equation is stainless steel. The other half is carbon fiber. Does that make it a non-metallic bearing? I don't know.

I'm really, really, absolutely, positively sure that this is simply an issue of the stainless inner race pressing hard enough on the carbon outer race that it is creating friction during the heaviest part of the load cycle in a very limited set of sailing conditions. Hence the plan to replace these with roller bearings at the next haul. In the meantime, I wish to lubricate them with something to help out with this small issue.

So, I guess that my question is, considering the materials involved, am I actually going to destroy carbon fiber with any type of lubricant?

Thanks, I don't mean to be snippy, but this same thing keeps coming up, and it's just not happening that way.

Insight into lubricants destroying carbon would be appreciated, however.

TJ
Don't know anything about your boat but the reason I say 10K nm is sort of short is because you can't make it very far in 10K nm. I previously wouldn't have thought this but we just managed to rack up 4.5K nm in one fairly lazy summer of coastal cruising here on the US West coast.

The Jefa bearings are available online in a number of sizes and configurations and they do custom work. It seems a phone call between your boat designer/naval architect and you to get the drawings so you can send them over to Jefa will do it.

Is there a reason your designer is not already supporting you on this? Usually they're very helpful even if you're not the original purchaser of the vessel.

Best of luck.
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Old 18-06-2016, 19:09   #29
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Re: Lubricant for rudder bearings

salt water works ok /olive oil works on all metal/lanolin spray with long tube clipped in/from crc might get the lube in
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Old 18-06-2016, 19:22   #30
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Re: Lubricant for rudder bearings

Good thread - why? a) Nothing more important than steering on a boat, b) bearing replacement is a hell of a job. I replaced my top & bottom on a Cavalier 37 - s/s shaft and acrylic bearing custom made by mining engineers. On removal of old bearings I noticed fair bit of 'deposit' on working surfaces. I'd be wary to get this right for pressure surfaces with intermittent submersion in salt water I'm interested in the change in chemistry and crystalline formation in 'greases' - slippery when new and mildly abrasive when aged. Any comments and may also help our friend here?
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