SS316 Bolt heads missing in Tinned Ground plate

Discussion in 'Boatbuilding' started by alby joy, Sep 11, 2020.


Reason for this

Poll closed Sep 18, 2020.
  1. Galvanic corrossion

    0 vote(s)
  2. Som other reason

  1. alby joy
    Joined: Jul 2017
    Posts: 33
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    Location: india

    alby joy Junior Member


    Recently when I drydocked my FRP Vessel with Tinned ground plate attached to its hull - Catamaran. The plate attachment bolts used was SS316. Now I cant see any Bolt heads for the Bolts (SS316). Is it have an issue related to the galvanic corrossion.

    Attached Files:

  2. sdowney717
    Joined: Nov 2010
    Posts: 955
    Likes: 53, Points: 28, Legacy Rep: 274
    Location: Newport News VA

    sdowney717 Senior Member

    Regardless, can you replace with bronze bolts, washers and nuts? Obviously the SS is having issues. All my underwater bronze bolts underwater for 50 years have been excellently preserved.
    jehardiman likes this.
  3. jehardiman
    Joined: Aug 2004
    Posts: 2,866
    Likes: 413, Points: 83, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    If the heads are gone, but the body is intact, it is crevice corrosion which 316 is susceptible to. As sdowney717 says, switch to bronze or monel.
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