Cutlass bearing, how old is old?

Discussion in 'Inboards' started by missinginaction, Sep 1, 2012.

  1. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    My first post in this section. I've been restoring a 73 Silverton for the past few years. I need to take a break from my woodworking/glassing so I'm going to address the rudder/cutlass bearing/prop.

    It seems that replacing the cutlass bearing is a good idea since the shaft is out of the boat. Just a 1 1/4" bronze shaft in good condition with the exception of some wear in the packing gland area. I've picked up a Packless Shaft Seal to replace the old stuffing box so the wear there shouldn't matter.

    My question regards the cutlass bearing. The previous owner gave me a new one. That was 10 years ago and my guess is that the bearing is probably 15 years old but never used. So I have a new bearing that's about 15 years old in the box. My only concern is the rubber insert. Do these dry out over time or do you all think that my concern is unwarranted? It looks OK to me.

    Thanks in advance for any replies,

    MIA
     
  2. PAR
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    PAR Yacht Designer/Builder

    They can dry out, but they need to be UV exposed or cooked in an oven if not used. Personally, I wouldn't trust, but can't offer a reasonable or logical reason for not. I've found old rubber parts, regardless of use, fail at a higher rate than new ones, so I'd just replace it and start with a level playing field, rather than wonder about the old one. At least this is the approach I use with wife selection . . .
     
  3. missinginaction
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    missinginaction Senior Member

    That's what I like about you Paul. There's always this little bit of the "old philosopher" in you. It leaks out in your posts.

    Regards,

    MIA
     
  4. FAST FRED
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    FAST FRED Senior Member

    I've picked up a Packless Shaft Seal to replace the old stuffing box so the wear there shouldn't matter.

    I would install Duramax packing and return the packless goodies.

    While the shaft will not need to be repacked , the rubber must be replaced on a sked, and its a bigger job than just tighting a shaft packing.

    Should you FAIL to replace the rubber and it should fail half a dozen bilge pumps cant keep up.

    FF
     
  5. Tigawave
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    Tigawave Junior Member

    Why use rubber when there are composite bearings?
     
  6. michael pierzga
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    michael pierzga Senior Member

    a cutlass can be destroyed in one year. Replace the cutlass while you have the boat in service...its cheap and easy
     
  7. keysdisease
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    keysdisease Senior Member

    The list price for a new 1-1/4" cutlass bearing is around $100. Not worth taking the chances involved with installing a 15 year old unit, especially for a part that involves a trip to the travel lift to replace.

    $0.02 Steve :cool:
     
  8. missinginaction
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    missinginaction Senior Member

    Thanks Steve, appreciate it.

    MIA
     
  9. tom kane
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    tom kane Senior Member

    cutlass bearing,how old is old

    I agree,composite bearings for me they gave better service than rubber and less wear on shaft
     
  10. Tigawave
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    Tigawave Junior Member

    There's been some hard evidence recently from UK pilot boat that showed wear rates at a third of that of a good quality rubber bearing, so the tide is turning. Those were Maritex an Australian material.
     
  11. tom kane
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    tom kane Senior Member

    Novasteen bearings I found lasted for ever especially used at engine revolutions (fast spinning) and almost no friction whereas rubber bearings had lots of drag and needed plenty of lubrication and burned the shaft in sandy water. That is with surface drive and sub surface drive.
     
  12. Tigawave
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    Tigawave Junior Member

    Novasteen seems to be an older form of a phenolic and cotton material, quite good but possibly suffering from higher thermal expansion than Maritex and without some of the more advanced lubricants. I've never come across it before in my work.
     
  13. tom kane
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    tom kane Senior Member

  14. Tigawave
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    Tigawave Junior Member

    As I thought, this material is a phenolic cotton composite fibre layered. A more recent development (10 years old now) is Maritex from Perth Australia these guys
    http://www.maritexbearings.com/ have documented proof from commercial vessels showing very low wear rates of bearing and more importantly the shafts. They do not use cotton as a fibre and they are not fibre wound but moulded. They are the material of choice for builders like Austal.
     

  15. Frosty

    Frosty Previous Member

    I Thialand the big trawlers use wood. Big lumps of it soaking in stinking tubs ready for placing in a 4 jaw chuck and turned. The shaft size will be 4 to 6 inch swinging huge props then they go out at tow nets 24 7 for 2 years.

    If you want to know what works see what fishermen do.

    If your getting wear it is probably due to the silt or sand content in the water especially if you a mudder.
     
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