Page 1 of 3 123 LastLast
Results 1 to 10 of 24
  1. #1
    Join Date
    Jul 2001
    Location
    Cyberspace
    Posts
    34,921

    Default Tightening propellor bolts

    .
    When we bought Avy-J we antifouled her, launched her and sailed/motored her down to our local yard before lifting herback out for refitting. We then noticed the prop locknut was loose.

    I finally got round to tightening it today and noticed that the top nut (nearest the prop) was also slightly loose. These seem to be bronze nuts on a ss shaft.

    Is there a specific torque, and should I use some form of loctite or similar?


    - W

  2. #2
    Join Date
    Apr 2003
    Location
    The Gareloch
    Posts
    3,784

    Default Re: Tightening propellor bolts

    “Top nut”? Are you saying there is more than one? The usual arrangement is a castellated nut and a hole in the shaft through which you can fit a split pin. On a stainless shaft the nut should be brass.

  3. #3
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    43,316

    Default Re: Tightening propellor bolts

    Quote Originally Posted by webcraft View Post
    .
    When we bought Avy-J we antifouled her, launched her and sailed/motored her down to our local yard before lifting herback out for refitting. We then noticed the prop locknut was loose.

    I finally got round to tightening it today and noticed that the top nut (nearest the prop) was also slightly loose. These seem to be bronze nuts on a ss shaft.

    Is there a specific torque, and should I use some form of loctite or similar?


    - W
    The nut closest to the to the prop should be tightened first to ensure the prop is tight on its taper. If it is loose the key may become damaged or even shear. It would be a good idea to remove the prop, if you can, and check the key although it is the tightness on the taper which should transmit the driving torque rather than the key

    The second nut, should be tightened against the first to lock it. If you have a full nut and a half thickness nut the half nut goes on first, followed by the full nut ( although I bet that will be contested).

    Loctite might be a good idea. ............... Sorry cannot help with torque figures

    If the shaft is drilled for a split pin then a castellated nut, as suggested by Porthandbuoy, would be the more sensible.
    Brass can dezincify, bronze wont, so I don't know why he is suggesting brass
    Last edited by VicS; 15-06-19 at 06:55.

  4. #4
    Join Date
    Dec 2001
    Location
    Grenoble
    Posts
    29,634

    Default Re: Tightening propellor bolts

    Quote Originally Posted by Porthandbuoy View Post
    “Top nut”? Are you saying there is more than one? The usual arrangement is a castellated nut and a hole in the shaft through which you can fit a split pin. On a stainless shaft the nut should be brass.
    Or a locking tab washer.

  5. #5
    Join Date
    Oct 2018
    Location
    A Member State of the European Union
    Posts
    4,941

    Default Re: Tightening propellor bolts

    Quote Originally Posted by VicS View Post
    ... If you have a full nut and a half thickness nut the half nut goes on first, followed by the full nut ( although I bet that will be contested).
    ...
    That is what I was taught ; and it makes senses.

    http://www.boltscience.com/pages/twonuts.htm
    " Brexit is like watching a library being burned down by people who can't read"

  6. #6
    Join Date
    Nov 2013
    Posts
    2,617

    Default Re: Tightening propellor bolts

    Bronze nuts on a SS shaft are fine - either you should be drilled for a split pin or, if not, there should be a tab washer as Fr J says. There is no need to torque as it's the taper that does (should do) the work. Just use the first nut to get the prop hard onto the taper then use the second (with either a tab washer or pin) to lock the first nut. No need for loctite or whatever.
    It's not my fault if people choose to take me seriously.

  7. #7
    Join Date
    Nov 2001
    Location
    Medway
    Posts
    19,638

    Default Re: Tightening propellor bolts

    Did have a boat where bronze prop nut was not tight on stainless shaft., attempted to retighten.
    Thread simply crumbled away .
    When replacing shafts later, used stainless lock washers and stainless loc-nuts.
    Split pins and castellated nuts simply too much hard work.
    Last edited by oldgit; 15-06-19 at 07:19.

  8. #8
    Join Date
    Jul 2001
    Location
    Cyberspace
    Posts
    34,921

    Default Re: Tightening propellor bolts

    No castellated nut, no hole. Just two equal size bronze nuts. What exactly is a tab washer and how should it be fitted? (There is only 1 thread sticking out of the 2nd nut)

    - W

  9. #9
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    43,316

    Default Re: Tightening propellor bolts

    Quote Originally Posted by webcraft View Post
    No castellated nut, no hole. Just two equal size bronze nuts. What exactly is a tab washer and how should it be fitted? (There is only 1 thread sticking out of the 2nd nut)

    - W
    A washer with a "tab" or two tabs sticking out of the side that you bend up/ down the side of the nuts to stop them undoing .......... Goggle it !

    If appropriate the washer may also have an internal tab that locates in the shaft key way .

    BTW Bronze nuts are used to avoid the risk of galling if stainless steel nuts are used on stainless steel
    Last edited by VicS; 15-06-19 at 08:18.

  10. #10
    Join Date
    Nov 2009
    Location
    Home UK Midlands / Boat Croatia
    Posts
    18,881

    Default Re: Tightening propellor bolts

    Quote Originally Posted by webcraft View Post
    No castellated nut, no hole. Just two equal size bronze nuts. What exactly is a tab washer and how should it be fitted? (There is only 1 thread sticking out of the 2nd nut)

    - W
    A tab washer isn't going to be that useful unless the threaded part of the shaft has a flat machined into it.

    My saildrive prop shafts were stainless and had no flat so I used two stainless nuts locked together, the outer of which was a Nyloc. No need for Loctite.

    Richard

Page 1 of 3 123 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Latest YBW News

Find Boats For Sale

to
to