Dinghy Davits - single point of failure

Discussion in 'Dinghies' started by hynespa, May 20, 2020.

  1. hynespa

    hynespa Active Member

    217
    Jun 7, 2010
    Marina Del Rey, CA
    2005 420 Sundancer
    T-VD-8.1 S HO MerCruiser (T-420 hp)
    I have St Croix Model 350 removable dinghy davits to hoist my dinghy up from the water to my swim platform as I detailed in this 2018 post:

    http://www.clubsearay.com/index.php?threads/420-da-thread.1273/page-75#post-1013007

    As my wife and I were hoisting the dinghy up on Sunday, the rear of the dinghy suddenly gave way and splashed down into the water. Luckily nobody was hurt and the dinghy was not damaged - but the failure occurred on the piece I circled below which I later learned is called an "Stainless Steel Stamped Shackle". I was able to purchase a new one at West Marine - but I am now aware of how this is a single point of failure - I am surprised the St Croix wouldn't have designed a little bit beefier part here.

    Now that I am more aware of this - I am looking to add in a second line of redundancy in case the D Shackle fails again. I was considering two possibilities:
    1) Use "Stainless Steel Seizing Wire" to make multiple wraps from the U/V shaped piece coming off of the bottom of the pulley around the O ring attached to the other end of the eye jaw toggle.
    2) Use a "Stainless Steel Cable Tie" following the same route (the problem is that the ring is rotated the other way).
    3) Something else I'm not thinking of?? - CSR guru's any suggestions?

    Screen Shot 2020-05-19 at 10.35.34 PM.png
     
    Last edited: May 20, 2020
  2. Sea Gull

    Sea Gull Well-Known Member

    Oct 19, 2006
    CT
    2019 Maritimo M64
    Volvo D13-1000
    That eye jaw toggle looks too flimsy for the job. In this photo it looks deformed. I also see a great deal of corrosion and wear in this setup. The wire rope eye splices are not well done and are corroding. The line in the block and tackle is frayed, etc.

    I would replace the failed part with a more robust version and replace other worn/corroded parts. Given the location of this set up, I would think a fresh water washdown after every run is critical, as is a frequent and generous coating of corrosion blocker.
     
  3. hynespa

    hynespa Active Member

    217
    Jun 7, 2010
    Marina Del Rey, CA
    2005 420 Sundancer
    T-VD-8.1 S HO MerCruiser (T-420 hp)
    Thanks @Sea Gull - I appreciate the observations. I agree that the D Shackle is too flimsy but when I went the next size up the Clevis pin was too thick to fit into the holes on the bottom of the pulley. Any suggestions on a replacement?

    I also appreciate your comments on the rinse down and corrosion blocker. Is there any particular one you would recommend?
     
    Last edited: May 20, 2020
  4. swaterhouse

    swaterhouse Active Member GOLD Sponsor

    574
    Jan 7, 2015
    Mattapoisett, MA
    boatless
    boatless
    That is a pretty cheap block setup. You can get much higher quality components made by Harken, Scheafer or Ronstan from anywhere that sells sailboat hardware (including west marine). Don't be shocked too much by the price, it wont be cheap but it will be much higher quality.

    I also agree with the other comments about the line and wire rope parts of this system.

    If you want a safety I would add a secondary fixed bridle from the top of the davit to the lifting points of the dinghy, that would make the whole block and tackle setup redundant (but not give you the ability to raise and lower should the bock system fail). For this I would use spectra line, the strength of wire with none of the headaches.
     
  5. swaterhouse

    swaterhouse Active Member GOLD Sponsor

    574
    Jan 7, 2015
    Mattapoisett, MA
    boatless
    boatless
    For corrosion prevention my favorite is Boeshield T-9.
     
    hynespa and techmitch like this.
  6. hynespa

    hynespa Active Member

    217
    Jun 7, 2010
    Marina Del Rey, CA
    2005 420 Sundancer
    T-VD-8.1 S HO MerCruiser (T-420 hp)
    Thanks @swaterhouse - the one pictures is the original (from the bow that didn't fail - yet). The replacement I bought was a Harken Stainless Steel Stamped D Shackle. However the Clevis pin that came with the size I bought did not fit the drilled holes on the pulley. I had to go down to a 3/16" by 3/4" West Marine clevis pin.

    I really like your idea of adding a second bridle to the dinghy lift points - I had never thought of that but I am going to try and make that happen.
     

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