Masthead sheave pin removal

  • January 21, 2021 12:38 AM
    Message # 9886415

    Can anyone share the secret with me on how to remove the stainless steel pins from the masthead? I am trying to remove and replace the sheaves in the masthead. There are two sets of three sheaves rotating on a stainless steel tubular axis. I have removed the cover plates but I cannot come up with any way to get a grip of the stainless steel pin to extract it. It is cut flush with the mast profile (on an angle) so there is no lip to get any pliers on to and I am not able to rotate it. There does not appear to be any threads or recesses in the internal bore of the pipe so nothing to hang on to. The pins are in a captive hole, there is no access from the other side and they cannot be driven/punched through… It has me beat.

    I have been up there about four times in the last two months and I drench the entire area with a spray on commercial penetrating release agent.

    Not making it easier is that I really had no intentions of lowering the mast but would like to get this done with the mast standing.  I searched the forum but this issue does not appear to have been raised by anyone else. Do they just move freely and are easily extracted on other people’s boats? Advice would be much appreciated.

    1 file
  • January 31, 2021 8:45 PM
    Reply # 10052203 on 9886415

    Ben,  The easy way is to drill a hole on the opposite side of the mast in line with the axle pin of the sheave.  Then use a small punch to drive the pin out of the open side.  Then you can use a vise grip on the exposed pin and rotate it out.  Easy solution since I have done it many times before.  Bud

  • January 31, 2021 11:17 PM
    Reply # 10052316 on 9886415

    Thanks Bud,

    I appreciate your feedback and like your optimism.

    I just wanted to check with you where exactly do you drill this hole in relation to the sheave axle pin. Probably not the end of the world but I would like to avoid a bunch of unnecessary holes. As the sheave pin is a hollow tube do you drill it so the punch will align with the wall thickness of the axle pin (so offset from the centre line), or is the axle pin welded shut at the captive end so one can drill on the centre line and knock it out nice and square?



  • June 21, 2021 1:14 AM
    Reply # 10677962 on 9886415

    I can report success, finally. I did try Bud's suggestion but was not able to move the pin. I was swinging a lump hammer, the biggest hammer I could still use with one hand, but the pin did not budge. There was a fair bit of bounce in the mast which was absorbing quite a bit of the force of each blow. I suspect that if the mast would have been on the ground and supported the pin probably would have moved.

    Instead I ended up removing the fore-stay which finally gave proper access to the sheaves from the front of the mast. Then I cut straight through one of the sheaves and the stainless steel pin from top to bottom with a reciprocation saw. As I had previously drilled into one of the sheaves, as soon as it was cut through as well it came out in pieces and I could take out one after the other.

    Now they are replaced with new Acetal sheaves and putting it back together was just a breeze.

Powered by Wild Apricot Membership Software