substitute for Tufnol as bearing material on rudder posts?

Discussion in 'Materials' started by Contorta, Apr 1, 2011.

  1. Contorta
    Joined: Mar 2011
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    Location: Prince George, BC

    Contorta Junior Member

    My plans call for Tufnol as bearing material on my rudder posts. I am having difficulty finding the product in North America (at a reasonable price). Can anybody recommend a substitute?
     
  2. michael pierzga
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    michael pierzga Senior Member

  3. Contorta
    Joined: Mar 2011
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    Location: Prince George, BC

    Contorta Junior Member

    Thank you Michael, I am sure your suggestion will work well. My designer is not in the habit of answering his Email.
     
  4. Tad
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    Tad Boat Designer

    The bearing material depends on load, in Prince George I'm guessing a trailerable boat? For that almost any medium to high density plastic will do. UHMW plastic is popular and available in tube or rod blank that can easily be turned to fit by anyone with a small lathe.......See the remainder bin at your local Industrial Plastics dealer.......

    UHMW does swell a fraction in water so be careful to oversize slightly........

    There's also a self lubricating version of UHMW called Murlubric....which is nifty
     
  5. michael pierzga
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    michael pierzga Senior Member

    Always Best to get the input from yacht designers and Plastics professionals. Many plastics are suitable for low tech applications like a rudder bearing. Water swelling, heat distortion and friction wear are well known and can be allowed for when you machine the bearing or wish project its useful service life. . A good plastics supplier should be able to advise you on available materials for your application.
     
  6. Tigawave
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    Tigawave Junior Member

    A more recent development in bearing materials is a phenolic based self lubricating bearing material known as Maritex Aquarius. This has advantages over UHMW plastics in that it is non melting/softening and can support high loads with less distortion, it also has surface chemistry to resist marine growth. It is being used in everything from the Panamax project to new submarine shafts and dive planes, but is also available for shafts from 1" to over 22". It can be used with water, oil or dry.

    It machines without dust or fumes and is dimensionaly stable over a wide temperature range. Clearance calculators can be found if you search for maritex aquarius calculator
     
  7. brian eiland
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    brian eiland Senior Member

    This is a very interesting subject,....that didn't get a lot of exposure.

    I utilized some UHMW plastics to fabricate the rudder stock and other parts on my Firefly trimaran project...in lieu of expensive and involved SS fabrications with additional bearings needed.

    Thought I might add this posting to remind myself in the future.
     
  8. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Contorta,

    I looked up the web site for Tufnol and found there were 5 different types of laminates.
    Do you know which kind is specified for your boat?
     
  9. gonzo
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    gonzo Senior Member

    What material are the rudder posts made of?
     
  10. Steve W
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    Steve W Senior Member

    Ertylite (sp) is another engineered plastic that could work, it does not absorb water as much as some, I have not used it for plain bearings but have used it for roller bearings for a rudder in a drum application which has worked well for many years now. Like Brian, adding as a reminder to watch the thread.
     
  11. mydauphin
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    mydauphin Senior Member

    It there any bearing material that can be poured in like an epoxy. Indeed how about an epoxy with graphite, (not for me Aluminum boat). I am tired of buying them, I want to make my own. Any recipes?
     
  12. gonzo
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    gonzo Senior Member

    Graphite and aluminum is a bad combination because of their different potential. There will be a lot of electrolysis. In general, rudder bushings last for many years. Are you operating where sand gets into them?
     
  13. waikikin
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    waikikin Senior Member

    I use some Ertalon LFX on gangway/brow components for slip handrail bearings, they have constant movement 24/7 and hold up well. Haven't used for rudder bearings though but also in thrust bearings to large windlass. Should go ok with appropriate clearance http://www.dotmar.com.au/ertalon-lfx/ertalon-lfx-oil-filled-nylon-rodssheets.html

    Jeff
     

  14. brian eiland
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    brian eiland Senior Member

    Maritex Aquarius

    I was looking that one up and came up with a few sites, since none were quoted:
    http://www.h4marine.com/Maritex01.htm

    http://www.engineeringexchange.com/forum/topics/effect-of-hardness-in-plastic

    http://www.exalto.co.uk/en/marine-bearings/maritex-bearings/
     
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