Gudgeon bolts rusted out: how to extract?

Discussion in 'Sunfish Talk' started by Foulweather Jack, Apr 8, 2017.

  1. beldar boathead

    beldar boathead Well-Known Member

    Likes Received:
    111
    Trophy Points:
    63
    At first I was thinking some sort of grinder, perhaps a dremel, would be easier to use than the burning idea. But then I realized that the simplest and fastest approach would be to get a small bit of plastic explosive, attach it around the screw, and blow it up. It'll quickly provide access to the backing plate.

    BB
     
  2. Light and Variable Winds

    Light and Variable Winds Well-Known Member

    Likes Received:
    138
    Trophy Points:
    63
    A backing plate has appeared at eBay. Those of us who've worked with stainless steel would guess this backing plate isn't made of stainless steel.

    Fullscreen capture 632017 72309 PM.bmp.jpg
     
  3. mixmkr

    mixmkr Active Member

    Likes Received:
    70
    Trophy Points:
    28
    I made a backing plate, in which you can really use two pieces of your choice of metal, not to mention some fender washers. A couple of pieces of "L" bar of aluminum worked great. I didn't have any plastic explosives though. Vise grips, sledge hammer and a chain saw are the only 3 tools you'll ever need working on a sailboat.
     
    • Like Like x 1
  4. Light and Variable Winds

    Light and Variable Winds Well-Known Member

    Likes Received:
    138
    Trophy Points:
    63
    Found while reading a Florida blog:

    "I twisted off two exhaust studs on the engine head when replacing the muffler on a Kohler 20 hp engine this week. “Dismayed” is not strong enough to describe the feeling. They snapped off short leaving angle-jagged nubs that were not very accessible to grab with vise-grips or to flatten and center-punch for drilling, but I found a solution that may help others.

    I threaded on a rod coupler, or more like hammered one on in one case.

    "Rod Coupler"...:
    [​IMG]

    Then I got a drill bit that just fit through the rod coupler and drilled a crater in the end of the broken stud that was well centered, thanks to the rod coupler’s guidance. Then I switched to a small drill bit to make the pilot hole. After about 4 hours of dulling drill bits and generating a lot of metal shavings and sweat, I had a very nearly perfectly centered hole through each stud that left only the threads to remove with a die tap.

    The common recommendation for removing broken bolts or studs is to drill a hole in them and then screw in an “easy-out”. My experience with that method has been mixed between either a successful removal or an easy-out snapping off in the broken bolt. Even when using an easy-out, the first thing needed is a well centered drill hole, and the rod coupling trick works very well for that.

    Another recommendation given on the internet is mig welding a nut onto the broken stud and then using a socket wrench on the welded nut. Not that I had a mig welder available, but if I was welding something to the broken nub, it would be a piece of bolt, and I would just use a few washers under the nut to take up the space where threads were destroyed. For me, it doesn’t have to be pretty or new, it just needs to work well."


    In addition to the above "workaround", I think it makes sense to drill as large a hole as possible to relieve the stress or rust keeping the stud immobile. Meanwhile, shoot some WD-40 through to the invisible side of the broken stud.

    .
     
  5. Foulweather Jack

    Foulweather Jack New Member

    Likes Received:
    2
    Trophy Points:
    3
    Sorry for the late follow up, guys. Having spent over $50 on cobalt drill bits (both right and left hand), as well as numerous screw extractors, I finally bit the bullet and installed an inspection port just forward of the transom. I used a hole saw to make the hole for the inspection port. After removing the lower screws from the gudgeon, I was able to take a punch and knock out the backing plate with a hammer and retrieve it through the inspection port. The backing plate was secured with a single layer of fiberglass cloth which was easy to cut with a utility knife.

    Next I was able to place the backing plate in a vise and back out the broken bolts from the internal side of the plate with a vise grip. Once the broken bolts were out I was able to replace the same backing plate over the transom and secure the gudgeon with new stainless steel screws.

    I figured out the reason why the two upper screws had failed in the first place: at the factory, the plate was fastened such that the lower aspect of the plate was flush with the transom whereas the upper aspect of the plate was not; thus salt water was able to repeatedly contact the inner aspect of the bolts thus causing them to corrode and ultimately fail.

    When the gudgeon was replaced I made sure to fasten it symetrically so that the shafts of the bolts are no longer exposed to the elements.

    I appreciate all of the advice on this forum for such a seemingly simple repair. Had it not been done properly it could have been devastating to the structural integrity of the boat.
     
    • Like Like x 1
  6. Light and Variable Winds

    Light and Variable Winds Well-Known Member

    Likes Received:
    138
    Trophy Points:
    63
    Thanks for the update. Most of us haven't experienced this kind of gudgeon problem, but DO have experience with "easy" and "difficult". :confused:

    Once the decision is made to install an inspection port, I would have replaced the factory's machine screws with s/s bolts and "Nyl0ck" locking nuts. Not sure where I read it, but some through-hull repairs have been done by filling-in holes (drilled larger than necessary) with epoxy, then threading them for the new bolts. (Assuring water-resistance).

    Though not stated, the above update strongly suggests that the backing plate is stainless steel.
     
  7. Foulweather Jack

    Foulweather Jack New Member

    Likes Received:
    2
    Trophy Points:
    3
    LVW,

    I did indeed use new stainless steel bolts with "nylock" locking nuts in my repair. As far as I could tell, the backing plate appeared to be stainless steel, although I didn't test it with a magnet. The plate itself had no corrosion. I sealed the holes with 3M silicone sealant when I placed the new bolts.
     
  8. Foulweather Jack

    Foulweather Jack New Member

    Likes Received:
    2
    Trophy Points:
    3
    IMG_0821.JPG IMG_0821.JPG IMG_0821.JPG IMG_0822.JPG
    Images of the plate once removed. I was able to use pliers to remove the proud end of the bolts from the internal aspect of the plate.
     
  9. Light and Variable Winds

    Light and Variable Winds Well-Known Member

    Likes Received:
    138
    Trophy Points:
    63
    Thanks again.

    Is that s/s plate as thick as it appears? (Maybe 3/16th-inch)

    Or are the sides folded in—like this ?

    .
     
    Last edited: Jul 13, 2017
  10. Foulweather Jack

    Foulweather Jack New Member

    Likes Received:
    2
    Trophy Points:
    3
    Yes, I would guess the plate is probably about 3/16 of an inch. It is quite solid. There is no fold to the sides.
     
  11. Light and Variable Winds

    Light and Variable Winds Well-Known Member

    Likes Received:
    138
    Trophy Points:
    63
    Vise-Grip makes the perfect tool for that purpose. Described as a 7-inch "locking wrench", and designed for bolts, it has a terrific grip at its tips. Used for nuts and bolts, it leaves the surfaces unmarred.

    https://www.amazon.com/Tools-VISE-GRIP-Locking-Wrench-Cutter/dp/B00004SBBD
    .
     
    Last edited: Jul 14, 2017
  12. Roller

    Roller Member

    Likes Received:
    20
    Trophy Points:
    8
    So Beldar wins his bet....
     
  13. Eddie_E

    Eddie_E Member

    Likes Received:
    8
    Trophy Points:
    8
    For those of you who are used to working on these boats I'm sure many of these questions seem basic but it occurs to me that there is a real possibility of creating significant damage if I don't think this repair through properly ahead of time.

    Intensity has the 5" ports for $8 or $20 with a storage bag insert. I Just installed one of each on Monday. Measuring is easy, as the inner lip of the screw in cover is exactly the same size as the needed hole. You simply trace the inside ridge with a sharpie and cut the hole with a Dremel tool, using a new fiber-reinforced cutting wheel for each hole and fine tuning the cutout with a Dremel sanding drum. The port is mounted with a dozen SS #6 x 3/4 screws after drilling pilot holes. Coat the ring on the port with pure silicon before the screws go in.
     
  14. Webfoot1

    Webfoot1 Active Member

    Likes Received:
    37
    Trophy Points:
    28
    The plate will be Aluminum. There is no way the factory is going
    to free hand drill stainless steel and not make a mess. Aluminum
    allows quick and easy drilling without going through a ton of drill
    bits. I did see a vid somewhere of factory production and someone
    was using what looked like a pneumatic hand drill.
     
  15. Light and Variable Winds

    Light and Variable Winds Well-Known Member

    Likes Received:
    138
    Trophy Points:
    63
    I'd agree that your measuring the exact diameter is a good idea. In my collection of inspection ports (for sale elsewhere here) the openings are not "as advertised" by the manufacturer! :confused:

    Your approach is to reduce the local "fraying" damage to the edges that a saber saw would cause? :(

    I might go one step further, and attach a reinforcing ring to fit inside. Two "C" shapes in aluminum, or one of cured fiberglass--bent to fit inside--would be my choice.

    BTW, save those cut-out pieces for possible repairs later.

    .
     
  16. Eddie_E

    Eddie_E Member

    Likes Received:
    8
    Trophy Points:
    8
    My opinion on saber saws and Saws-all cuts would be that any side to side movement tends to bind and pull rather than cut cleanly. In Sunfish fiberglass, the blade would be very dull half way around a single hole. That makes the binding worse and will rip and smash rather than cut. This is not just theoretical, I'm a high school carpentry teacher and we often have students build a beach game they call "corn-hole" that has a 5" port in plywood.
    Even though I have a high end jig-saw with the ability to choose orbital and straight cuts and 40 years of carpentry experience, my odds of doing that on a Sunfish without tearing chunks of gel-coat are less than 90%.
     
  17. mixmkr

    mixmkr Active Member

    Likes Received:
    70
    Trophy Points:
    28
    That's why you use a fine tooth blade and tape over where you are cutting. Although pricey, a quality hole saw of that diameter is the best method.
     
  18. Light and Variable Winds

    Light and Variable Winds Well-Known Member

    Likes Received:
    138
    Trophy Points:
    63
    My latest Sunfish is a '78 — and has a rear inspection port. :)

    Not sure if I can get a better image, but it appears to have a stainless-steel backing plate. :oops: (For "The Record") ;)
    The (added) transom drain passes through a much thicker piece of Sunfish than my '76. :confused:
    The interior stainless-steel plate appears to have been glassed over. (?)
    The dual ?? in the photo indicates some kind of margin. Is the margin that "glass-over"?
    (The "—C/L—" is the vertical centerline of the gudgeon).
    Fullscreen capture 1192017 12650 AM.bmp.jpg
     

Share This Page