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Keel Bolt Corrosion

Discussion in 'Thinking of buying a Moody ask a question here' started by John Dekkers, 12/11/17.

  1. John Dekkers

    John Dekkers John Dekkers Registered Guest

    Messages:
    5
    Am looking at a 1991 Eclipse of which many people advise the keel bolts should be an item of special attention due to corrosion of the mild steel. In the pictures I have seen, they appear to be studs, not bolts. I am assuming these are studs are just screwed into the keel (not J bolts that would be impossible to remove). Has anyone here taken on the project or had it done? What were the condition of the studs upon removal? Is it something worth doing if there are no signs of leakage? Many people say you can just clean the rust up...but that does not address potential corrosion below the nut. In another forum, I read that the studs usually come out before the nuts come off. If I could rely on that, it would seem to be a fairly easy fix to just replace them one at a time. Cost to have it done? Anybody gone the route of Titanium replacements?

    Thanks for any insight!
     
  2. Peter Wright

    Peter Wright Peter Wright

    Messages:
    1,791
    Boat name:
    WILD THYME
    Berth:
    Suffolk Yacht Harbour
    Boat type:
    Moody 425
    Cruising area:
    North Sea, English Channel, Biscay
    Hi John,

    Welcome to the MOA.

    The mild steel keel bolts in the Eclipse are the same as in other Moodys and Sigmas of this era, all built by Marine Projects (now Princess Yachts) of Plymouth. They seem to be a concern to surveyors of less than 40 years age, but not to the survivors of earlier times.

    If you take up a Temporary Membership (see the "Membership Types - what's the difference?" box on the home page) you will get access to pages of detailed descriptions on this site. If you don't wish to do that, I will summarise here:

    The keel "bolts" are, as you guessed, mild steel studs set in tapped holes in the cast iron keel secured with mild steel nuts bedded on rectangular mild steel plates in the bilge. The concern arises because the plates, nuts and the top end of the studs can become corroded by bilge water if not properly cared for. Many members have with drawn a single stud and found that the condition of the stud from the nut downwards is immaculate. Generally in this case they have simply wire brushed the remaining studs nuts and plates then painted them to keep corrosion at bay.

    There is the odd case of corrosion found below the nut, usually associated with failure of the seal on the keel to hull joint allowing sea water into the studs, but this is rare. Despite this, I have never heard of a Moody keel coming off the boat even in cases of severe grounding where damage has been caused to the grp keel stub to which the keel is bolted.

    There are many arguments made for mild steel vs stainless steel, mostly centred around the phenomenon of crevice corrosion in austenitic stainless steels. I can only observe that I have never heard of a yacht's keel bolt failure being attributed to this mechanism despite the use of stainless steel for keel bolts being widespread nowadays.

    As you say, attempts at removing the nuts often result in the whole stud coming out - if it doesn't the stud can easily be removed by use of a locknut. Rest assured that if you buy a Moody and join the MOA you will have copious advice on this issue. I would not bother with Titanium, but use mild or 316 stainless according to your view on that debate. I used stainless, despite my age.

    Peter.
     
  3. Phil Newman

    Phil Newman Phil Newman

    Messages:
    19
    Boat name:
    SCHEHERAZADE
    Berth:
    Troon
    Boat type:
    Moody 422
    Cruising area:
    Clyde/West Coast Scotland
    My experience of the Keel Bolts on my 422 mirrors Peters view above. The surveyor (under 40!) noted that they were excessively corroded, the insurance company required me to check, this is what i found:

    1.At survey,
    2 & 3. bolts as extracted, bright and oily as the day they were inserted,
    4. Bolts after a few days exposure to atmosphere,
    5 & 6. Replacements.
    20170129_131801.jpg 20170129_122815.jpg 20170129_124628.jpg 20170212_161921.jpg IMG_20170211_111322.jpg 20170211_110226.jpg

    I am sure that the 30 year old originals would have seen me out, I suspect their replacements will see the next generation out.
    My advice is draw one for peace of mind, then just clean up the nuts, rustproof, paint them, go sailing.
    Regards,
    Phil
     
  4. John Dekkers

    John Dekkers John Dekkers Registered Guest

    Messages:
    5
    Peter and Phil, thank you so much for your reply. This is exactly the thing I was hoping to see...thanks for the pictures! Puts my mind at ease somewhat that this may not be such a major issue. For such a critical item I would think pulling at least a couple maybe every 10 yrs would be a good idea to ensure no moisture penetration and resultant corrosion.
    I found another thread with a quote from David Moody "The owner inquiring about rusty keel bolts should be aware that their inspection and withdrawal is well overdue as they appear to be 25 years old. I repeat, it is what you can't see that is more important and the withdrawal of keel bolts for inspection should be carried out at regular intervals".
    My background is aviation maintenance and it only makes sense to me that such a critical item be given the attention it is due. We inspect things thousands of times on airplanes and find no fault, but for that one time that you do find something, it is entirely worth it. Phil, I think even though your bolts ended up looking fine, you were smart to have pulled them. Below is a picture of the kind of thing that I fear where the bolt looks just fine on top but is half gone below (not sure what boat this was from). It is very encouraging to know that the process for removal and installation does not require a full keel drop and looks like a reasonable job to carry out. Thanks again for sharing your experiences.

    Cheers,

    John
    [​IMG]
     
  5. Peter Wright

    Peter Wright Peter Wright

    Messages:
    1,791
    Boat name:
    WILD THYME
    Berth:
    Suffolk Yacht Harbour
    Boat type:
    Moody 425
    Cruising area:
    North Sea, English Channel, Biscay
    Hi John,

    If the keel to hull joint is still good, the studs can easily be replaced one at a time. However, if that joint is failing, the only proper repair is to deop the keel and remake the joint. If a boat is lifted for survey, it's worth watching the joint when she's put down so that her weight is on the keel - if water squeezes out of the joint, it's starting to fail. Also, rust along the joint generally indicates that the top face of the keel is rusting again showing that the joint is at least starting to fail.

    In my experience, it's rare to see wasted bolts like those in your photo on grp boats, much more common on wooden ones but I have read one report of wasted keel bolts on a Moody - it's somewhere on this forum.

    Peter
     
  6. John Dekkers

    John Dekkers John Dekkers Registered Guest

    Messages:
    5
    Thanks Peter, watching for water at the keel joint when compressed is a great idea. I have heard to watch for rust from the joint but it doesn't seem quite as conclusive as actually seeing water come from the joint. It is encouraging to hear that few Moody's seem to experience joint failure and that these bolts are normally fine.

    John