Rudder bearing - Peeved at cost.

[Monique]

I am upgrading some items on Pegasus... one of them is the lower rudder bearing which was seized in the cage.

I had a quote of north of 600Euros from Bavaria.... plus VAT.

Guess what? I am having one manufactured by XPC bearings in the USA for a fraction of the Bav price. Made from Vesconite too which does not absorb water.... hence unlikely to seize. Total price including Customs and Delivery should be less than 1/3 the price.

Why do yacht builders think they can fuque us like this and expect our return business?

I suspect all other yachts may need this service sooner or later, hence this post.

To make it easy for XPC to produce a perfect fit, take out your old bearing and ship it to them... presto, you will get a clone ...

Happy customer!!!

 

[colhel]

Is it just a plastic bush or have Bavarias got something more fancy?

 

[Monique]

The Bav bearing is Teflon. Over time, it absorbs water and restricts movement.

My boat is from 1997 so its been a simmering problem for a while. Vesconite is better for rudder bearings as it does not absorb water.

The cost from Bav... and I suspect Ben/Jen too.. is an assault on peoples intelligence ... Fuque them, I say!

 

[CreakyDecks]

600Euros is more than I paid for the mini-lathe I made my new bushes on!

 

[Monique]

My point exactly. This is not rocket science

 

[colhel]

Bloomin eck! Don't spose you still your old one?

 

[alahol2]

I know nothing of these bearings but I would have a word with H4 .
No link, just had very good service.

 

[nigelmercier]

600Euros is more than I paid for the mini-lathe I made my new bushes on!

I want one! Tell us more please.

What I don't understand though is how one can send a bearing that is clearly the wrong size as a pattern for duplication?

 

[ianabc]

UHMW bearings

Standard bearing material, Ultra High Molecular Weight....


basically long molecular chains of polethelene ....

Almost all boat builders here use this....inexpensive easy to machine and available in rods of varying diameter that may need little machining!


From wikipedia ...
"Ultra-high-molecular-weight polyethylene UHMWPE is a subset of the thermoplastic polyethylene. It has extremely long chains, with molecular weight numbering in the millions, usually between 2 and 6 million.

The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made.[citation needed] It is highly resistant to corrosive chemicals with exception of oxidizing acids; has extremely low moisture absorption and a very low coefficient of friction; is self-lubricating; and is highly resistant to abrasion,

Its coefficient of friction is significantly lower than that of nylon and acetal, and is comparable to that of polytetrafluoroethylene (Teflon), but UHMWPE has better abrasion resistance than PTFE.[citation needed] It is odorless, tasteless, and nontoxic."


and also from Wikipedia

"Dyneema and Spectra are gel spun through a spinneret to form oriented-strand synthetic fibers of UHMWPE, which have yield strengths as high as 2.4 GPa (350,000 psi) and specific gravity as low as 0.97 (for Dyneema SK75).[4] High-strength steels have comparable yield strengths, and low-carbon steels have yield strengths much lower (around 0.5 GPa). Since steel has a specific gravity of roughly 7.8, this gives strength-to-weight ratios for these materials in a range from 10 to 100 times higher than steel. Strength-to-weight ratios for Dyneema are about 40% higher than for aramid."




see also an engineering company ....

http://www.slideways.com/Materials-Engineering-Specifications.html


and

 

[Spyro]

I needed 2 new half shell bearings for my semi skeg hung rudder on my Jeanneau. Dealer wanted over £200. I had set made up in delrin at QD plastics in Dumbarton for £70

 

[CET1]

We had a quote from Jeanneau Rrance of 65 euros for our Sunfast 36 bottom bearing which at the time i thought was not bad.

 

[Neil_Y]

Thanks Alahol,

Be very careful with sizeing of composite and plastic bearings. Firstly they all absorb water, Vesonite hi lube 0.5% from their data sheet http://www.vesconite.com/charts/specs.htm

A much more significant factor in bearing performance and fitting is the thermal expansion, If you size from an old bearing you won't be able to get your clearances to 0.02mm so I don't quite understand how anyone can do that? Clearance has a significant effect on wear, as a bearing wears its working surface area decreases rapidly and wear increases.

We will always insist on knowing the shaft size and the bearing carrier size, if the bearing goes into the carrier with any resistance it will reduce the ID. We use a calculator you can see here
http://www.h4marine.com/Downloads/Maritex AQUARIUS General Calculator REV 20100519.xls
For any given shaft and carrier you can see the clearances we allow for water absorption and thermal expansion as well as detailing clearance when the bearing should be changed.

Many materials are also melting or they soften (and expand) as they work hard or sail to warmer waters.

Yes there are a number of materials that work quite well as rudder or shaft bearings but you have to have someone in the supply chain that knows the clearances for your application. They should be able to give you running clearances and how they are made up.

So yes there are some great materials out there but be careful how you choose and how you fit.

And in some ways it is akin to rocket science (I came from Plasma physics background many years ago) The development in advanced bearing materials is quite incredible. Zero wear for 1000hrs dry running rudder simulation with final load at 20Mpa (2900psi) for 200hrs? Recent developments have seen composite materials with thermal expansion rates to mimic metal carriers as this has always been a problem when rapid temperature changes happen.

I also doubt if the bav bearings were pure teflon, as it's not a great bearing material since it is soft and maliable, it is likely that it was a compound with teflon as an ingredient or surface layer. Teflon as far as I know does not absorb water check here.
http://www.machinist-materials.com/comparison_table_for_plastics.htm

 

[CreakyDecks]

I want one! Tell us more please.

It's one of these

I got it off a guy in London who sells them on Ebay. There don't seem to be any on there at the moment, I suppose he ships a container load over at a time. They are made in China. It's similar to one Machine Mart sell but it has a higher spec for the same price (bigger chuck etc). The downside is that you have to clean the transport grease off yourself and make a few minor adjustments.

 

[Heckler]

It's one of these

I got it off a guy in London who sells them on Ebay. There don't seem to be any on there at the moment, I suppose he ships a container load over at a time. They are made in China. It's similar to one Machine Mart sell but it has a higher spec for the same price (bigger chuck etc). The downside is that you have to clean the transport grease off yourself and make a few minor adjustments.

Oooh, that looks nice! dead simple and easy to use.
I want one!
Stu

 

[RivalRedwing]

Oooh, that looks nice! dead simple and easy to use.
I want one!
Stu

one on e-bay at present: buy it now for £10k

 

[Monique]

Would want one too but I also want precision and given my ability with a precision machine, I better pay someone else for a good fit...

 

[CreakyDecks]

one on e-bay at present: buy it now for £10k

It was about £400 including delivery.

 

[savageseadog]

If everyone in Britain bought one of those lathes we wouldn't need to import anything from China again

 

[nigelmercier]

I got it off a guy in London who sells them on Ebay.

Nice! Can you post a link to the item, or the seller?

 

[CreakyDecks]

Nice! Can you post a link to the item, or the seller?

Ebay item 360344827331 is the guy. I don't know why it says £10,000. I assume he has no stock but just wants to keep the advert running.

This is also him
http://www.amadeal.co.uk/acatalog/Mini-Lathe.html
It says new stock coming in March. The price seems to have gone up about £30 since I got mine, but it's still much cheaper than the likes of Machine Mart.