Boomkin Failures

  • May 28, 2012 4:54 AM
    Message # 932854
    Motivated by WOA reports of W32s lost at sea because of boomkin failures. I ordered new boomkin and bowsprit tangs from Bud.  The new boomkin tangs are a bigger size than the old ones and they use carriage bolts.

    Yesterday I installed the boomkin tangs.  In the process, I was shocked when the head of one of the lower bolts simply sheared off with almost no force.  The same thing happened to me four years ago in a boat yard.  Also, four years ago one finger in the boomkin stay toggle was also found failed. I replaced them all so the bolt that failed yesterday was only four years old.

    I have been careful to follow Bud's instructions.  Put the lower bolt in first, tighten the turnbuckle, then put in the upper bolt.  That assures that the bolt holes, tangs and the stay are in alignment and do not have a residual sideways shear.

    If a W32 is lost at sea due to boomkin failure, we don't get to make a post mortem inspection to determine the actual cause of failure.  From this experience, I suggest that the bolts could be the cause of failures as well as any other parts in the chain including tangs.

  • May 28, 2012 9:38 AM
    Reply # 932996 on 932854
    Anonymous member (Administrator)

    Dick:  Glad you found the bolt issue - can you explain how you tested / discovered that the head just sheared off - or how can others test their boomkin bolts while in the water.

    Also, is the lower bolt in the water while underway?  Should the lower bolt be bronze?


  • May 28, 2012 2:47 PM
    Reply # 933202 on 932854
    I just tried to turn it with a wrench when it broke.  It took about the same force to break as it would take to break a banana in half.  Inspection of the broken remains shows a corrosion crack essentially all the way through.

    On the previous occasion, it was the upper bolt head.  I just grabbed the upper end of the tang and gave it a tug. Ping, the bolt broke and the head flew across the yard.

    The lower bolt sits about 6 inches above the water line.

    Perhaps Bud can comment on bronze or any other options.  I think he recently gave us his inspection recommendations.  

    On my boat, because of carpentry in the engine room, access to the nuts on the inside of those bolts is very difficult.

  • May 31, 2012 12:45 PM
    Reply # 939198 on 932854
    The tangs and bolts should be removed and checked at every haulout.  The lower bolt should not be below the waterline.  If it is, either get rid of the excess junk you are carrying around. or move the tangs up and shorten the length of the boomkin stay.
  • July 02, 2012 1:51 PM
    Reply # 992331 on 932854
    Deleted user
    I have replaced the hull tangs four years ago. I am still concerned about the risk of failure and am now in the process of fitting an extra pair leaving the original rod stays and adding a pair of wire ones.Westsail32GT! It looks quite good and I am confident about the arrangment.This will mean I can check the bolts and tangs at alternate intervals.
  • July 03, 2012 2:53 PM
    Reply # 994216 on 932854
    Deleted user
    Another option is to shroten the boom to 14'-6" and get rid of that whole issue.
    for the simple solution, just use two of Bud's tangs (the lowers for the mast) and a little teak complete double or Bud has a split kit for this.

    No issues with the bolts 7+ years and counting. Also the inspection is easyer in the aft locker.

    Just food for thought.

    Ps. I did have the little tanks welded to Bud's tangs for the windvane (not stock)
    PPs. the old tangs down low I just had a hoop weld to and cut off the excess and reattached them (I will inspect these before I am back in the water, but other than tieing the dink to, they have not been used or have they leaked.
  • July 04, 2012 11:30 AM
    Reply # 995599 on 932854
    We're about to rerig our entire boat, she is due and we plan a long cruise.  I was thinking for the boomkin tangs and bolts, switching to titanium.  Also going to titanium carriage bolts for the chainplate and other critical parts.  Seems like it wouldn't be overly expensive on these smaller parts but would provide a lot more security.  Thoughts?