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  1. #1
    Join Date
    Oct 2007
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    UK
    Posts
    159

    Default Keel studs exposed on underside of keel flange

    I have had the keel off my elderly fin-keeler, the studs replaced (316 stainless) and the keel rebedded. The keel features a flange at the top that bolts into a recess in the GRP hull. For whatever reason, four of the new studs, the ones at the corners of the flange, are now visible (i.e they've come right through). I've not seen that before, on my boat or others. Is the fact that these studs are "exposed" a problem and, if so, is it a problem that will be fixed by cleaning back to bare metal and then filling and fairing?

  2. #2
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,902

    Default Re: Keel studs exposed on underside of keel flange

    The combination of stainless steel studs and iron(?) keel is a poor galvanic combination when immersed. It would be better if you could arrange a method of excluding water, e.g. plastic threaded caps with Sikaflex bedding.
    Answers to some technical queries at new website http://coxeng.co.uk

  3. #3
    Join Date
    Oct 2007
    Location
    UK
    Posts
    159

    Default Re: Keel studs exposed on underside of keel flange

    Vyv, thank you for your response.

    Yes you are right, it's an iron keel. Interestingly, when I was selecting a suplier to do the work, none of those I contacted mentioned a problem with stainless steel studs in an iron keel - in fact, all of them said they use 316 stainless steel as a matter of course. Perhaps they weren't expecting the studs to be routinely exposed to seawater (I wasn't either).

    Thank you for your suggestion regarding the plastic caps. Unfortunately the studs are flush with the exterior surface of the keel flange. To protect them against unwanted contact with sea water, and also to retain a fairly "clean" underwater surface, I'm going to have to encase them in something that: reliably adheres to iron and stainless steel; will, to all intent and purpose, remain completely waterproof while immersed indefinitely; either goes on smoothly or, more likely, is capable of being smoothed / shaped once it's set; will accept the normal underwater primers prior to anti-fouling. I don't know if Araldite complies with those criteria but that is the sort of stuff I am thinking might work. Am I on the right track? Is there a better material to use? Is there a better fix to this problem?

  4. #4
    Join Date
    Jul 2003
    Location
    West Australia
    Posts
    11,643

    Default Re: Keel studs exposed on underside of keel flange

    Araldite is an epoxy and should be fine to fair and seal the studs. ol'will

  5. #5
    Join Date
    Apr 2005
    Location
    Shropshire
    Posts
    8,871

    Default Re: Keel studs exposed on underside of keel flange

    Araldite is going to be an expensive option though. I would contact ECS to see if they can supply a cheaper equivalent.

  6. #6
    Join Date
    Oct 2007
    Location
    UK
    Posts
    159

    Default Re: Keel studs exposed on underside of keel flange

    Thanks all - your answers have been informative and, genuinely, much appreciated. An appropriate epoxy will be applied.

  7. #7
    Join Date
    May 2001
    Location
    UK East Coast
    Posts
    36,280

    Default Re: Keel studs exposed on underside of keel flange

    Quote Originally Posted by kacecar View Post
    The keel features a flange at the top that bolts into a recess in the GRP hull. For whatever reason, four of the new studs, the ones at the corners of the flange, are now visible (i.e they've come right through).
    I'd be tempted to unscrew these 4 studs slightly, enough to create a cavity in the flange into which you can apply an appropriate sealant. This will give a much better seal.

  8. #8
    Join Date
    May 2007
    Posts
    37,715

    Default Re: Keel studs exposed on underside of keel flange

    Quote Originally Posted by kacecar View Post
    I have had the keel off my elderly fin-keeler, the studs replaced (316 stainless) and the keel rebedded. The keel features a flange at the top that bolts into a recess in the GRP hull. For whatever reason, four of the new studs, the ones at the corners of the flange, are now visible (i.e they've come right through). I've not seen that before, on my boat or others. Is the fact that these studs are "exposed" a problem and, if so, is it a problem that will be fixed by cleaning back to bare metal and then filling and fairing?
    Studs should have been loctited into the keel, before the keel was assembled to the hull IMHO.
    That would pretty much have prevented corrosion between the SS and Iron and also crevice corrosion in the SS.
    If that was not done, or the bond was broken in torquing the nuts onto the studs, I might be concerned about corrosion in the threads.
    I'm not sure where you go from here. If you disturb those studs, then you risk compromising the seal around them and even the whole keel bedding.
    If the keel flange needs material added to fair it anyway, you could put some epoxy and glass tape over the studs after gringing them flush?

    BTW some epoxies which come in two tubes like consumer araldite are no good at all under water! I used some cheap stuff to fill a dinghy rudder blade and it swelled up strangely! I have used 'slow' araldite OK for this in the past, warming it up to make it set quickly.

  9. #9
    Join Date
    Oct 2007
    Location
    UK
    Posts
    159

    Default Re: Keel studs exposed on underside of keel flange

    Thanks for the further thoughts and suggestions. I'll see what can be done.

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