Bolt head fairing material?

Discussion in 'Materials' started by Deering, May 22, 2016.

  1. Deering
    Joined: Feb 2005
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    Location: Juneau, Alaska

    Deering Senior Member

    Hi all,

    I am trying to identify a material I've seen on a number of boats used to encapsulate/fair exposed nuts and bolts that are underwater, typically on rudders and shaft bearings and such.

    Looks like an epoxy putty - hard and sandable. It could be something like Splash Zone or MarineTex, but how would that stuff be removed if one wanted access to the bolt heads? Ideally it would be something relatively easy to chisel off when desired. Anyone used something like this? Suggestions?
     
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Heat works well, particularly on sunken fastener heads. A good whack with a hammer, can speed up the process too.
     
  3. SukiSolo
    Joined: Dec 2012
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    Location: Hampshire UK

    SukiSolo Senior Member

    On small craft with screw fixed metal keelbands, automotive body filler is often used. I think this is what you in the US call Bondo? If it is, it can be chiselled out usually. Easiest if the screws are slotted...;) You can do the same over bolt heads and then use heat, maybe a heated socket to get a grip on the head. Be a little careful on temperature, because polyester and epoxy do not neccessarily have similar softening temperatures, the range varies quite widely.

    You can always just grind a small chisel from a bit of flat bar if you need it just for one job. 3mm (1/8") thick stuff can be quite useful!.

    Btw digging out silicone is usually worse.....;)
     
  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    On slot, square drive or phillips head fasteners, I just heat a screw driver with a torch and press this into the putty. Then the slot (or whatever) is instantly cleaned out and the fastener heated a touch, to help withdrawing. The same is true of nuts and bolt heads. Fast, simply and it doesn't matter what type of filler is used.
     
  5. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Also consider counter sunk nuts..

    [​IMG]
     

  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The "barrel bolts" Michael suggests is a good choice and you can get little plastic inserts to fit in the hex hole to make them even more hydrodynamically efficient. I use these on kickup rudder pivot bolts and several other applications, though stainless and particularly bronze are hard to find, aluminum and mild steel are very common.
     
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