Failed screw hole repair

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BruceK

BruceK

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Joined
Oct 31, 2011
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Vessel Name
Sojourn
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Integrity 386
The material accommodating the hinge screws securing the heavy fiberglass hatch capping over the stairs leading to the FB has failed. Overloaded I think when we replaced the gas lift strut. The FB deck they screw into appears to have a foam core, definitely not wood. The holes appear quite elongated, as if the screws were moving/working long before we gave it the kiss of death. It`s possible the only holding material is the fibreglass top layer of the deck.
Aim is to create fresh material to screw into. I once used an epoxy paste into wood for the same purpose and had a lot of trouble getting it right down the hole, I`m thinking something thinner which flows into the hole, sets,and will accept a drill pilot hole followed by a self tapping screw appeals. Good if it adhered to the core material too.
Is simple epoxy resin used in fiberglassing a possibility? I also wondered if a simple plastic wall plug might work instead.
Any thoughts? Some branded products sold on the eastern side of the Pacific may not be available here but there`s likely an equivalent. JB Weld for example is sold here.
 
Greetings,
Mr. BK. I have had success, in the past, applying adhesives/fillers to holes and cracks by using a disposable syringe.
 
When screw holes for snaps get too big , i take a wooden golf tee & booger it up with your favorite adhesive. Whack that sucker in good, let it dry ,& redrill.
 
If you can get it, West Systems Six10 is really good for this. Comes in a caulking tube with a long nozzle, is pre-thickened enough it will not run out of a hole, even overhead. Stick the nozzle in the bottom of the hole and inject as you pull out.

The best solution would be a G10 fiberglass tube, tapped for the fastener size, bonded into the enlarged hole. A little more involved, but much stronger than self tapping screws in anything.
 
Don’t be afraid to make the hole larger. Be sure to find solid wood so the epoxy has something solid to adhere to. Wetting the wood with un thickened epoxy before putting in the thickened epoxy will help create a stronger bond.

You can also drive an epoxy coated wood plug into a hole that you have made larger. Drive your screw into the plug.
 
If you have a foam core then I would reef the foam back inside the hole. This way when you fill it with thickened epoxy the plug will be larger than the hole. I have a couple of Dremen bits for this purpose or an allen wrench with the short side cut down to about a 1/4” or so. Then stick the allen wrench or Dremel bit in the hole and run it around to reef out the foam. Vacuum the hole. I would first inject unthickened epoxy to seal the hole edges and then drain the unthickened epoxy out. Follow up with the thickened epoxy.

Marinehowto.com has an excellent article on this and also has the Dremel bit numbers.
 
When I had a cored boat, screws going into the coring were drilled over size and ideally drilled through. If the hole was on a horizontal surface, blue masking tape was used to cover the bottom of the hole. Unthickened West system was used to fill the hole. When it started to kick off, the tape was pulled off the bottom and the hole was drained into a cup. When the hole stopped draining, the bottom surface was cleaned and covered with wax paper. Then the hole was filled with fresh West System thickened with bonding compound. Once cured, drill and mount your hardware. As Mr. RT suggested, a plastic syringe works very well. The thickened West System should be about the consistency of latex paint.

If you don't want to through drill. Suck the epoxy out with the syringe before it kicks off.

For vertical surface, cover the hole with tape and poke the syringe through the very top. You will need to pump the syringe in and out to work the air out of the hole. Cover the syringe hole with tape after removing the syringe.

Unthickened West System permeates coring and wood better than almost anything. Adding bonding agent to the epoxy significantly increases the strength.

Ted
 
Greetings,
Mr. OC. I stopped using WM epoxies due to the layer of amine blush formed when it cures. The blush has to be removed (soap and water) to provide the best bond between cured epoxy and the new mix. There ARE other options. I still use the WM thickeners with the other brands of epoxy-works fine.
 
Last edited:
Reef it out, vac it clean, and inject thickened epoxy with a syringe. I prefer to leave the outside glass layers intact. Do this carefully and you won’t have to fix it again.
 
RT Firefly said:
Greetings,
Mr. OC. I stopped using WM epoxies due to the layer of amine blush formed when it cures. The blush has to be removed (soap and water) to provide the best bond between cured epoxy and the new mix. There ARE other options. I still use the WM thickeners with the other brands of epoxy-works fine.
Click to expand...
When filling holes, it's not necessary to allow the epoxy to cure between the 2 step process (eliminating any possibility of the blush) and is actually better to let the two steps chemically bond. The unscientific rule is if you finger nail can still make an indentation in the surface of the curing epoxy, it's ok to add another layer. Have done several layers with cloth like this with more than an hour between layers.

Ted
 
I've had good luck with Six10. And a couple times with a JB double syringe of 2-part epoxy, on smaller holes.

-Chris
 
I use mma adhesives in applications like this. They’re tough as heck, and you can drill and tap them.

Plexus® MA300 Adhesive | U.S. Plastic Corp.

Plexus® MA300 Adhesive is a two-part methacrylate adhesive designed for structural bonding of thermoplastic, metal, and composite assembl...
www.usplastic.com www.usplastic.com
 
I had a couple of snap screws pull out of grp at an inopportune moment. As a quick fix, I wrapped the screw threads with a couple layers of thin plastic packaging tape, thus making the screws a bit fatter. Screwed them back in hard and seated them. That "temporary" fix was three years ago and I've had little incentive to re-visit the issue. But when I have to, my plan will to be fill the holes with epoxy and drill them out to the right diameter.
 
ranger58sb said:
I've had good luck with Six10. And a couple times with a JB double syringe of 2-part epoxy, on smaller holes.

-Chris
Click to expand...
Thanks Chris. West System Six10 looks ideal, 190ml cartridge gun tube, self mixing, a nozzle that gets you down the screwhole. Issue looks to be availability locally. Even at Amazon US. There may be a local substitute in a 14ml pack, ? intended as single use, but the West one looks preferable.
 
If you go with the Six10, buy a couple of spare nozzles. You cannot clean out the nozzles, they are a one time use. You can unscrew the nozzle and discard it, carefully scrape the openings, and recap it (mark the cap before you remove it so that the hardener side stays on the hardener side!). Six10 has a shelf life of a year or two, what happens is the thickeners get lumpy, though it will still harden. The nozzles are ideal for filling holes, because you can start filling from the bottom and get all the air out. As I said it will not run out of a hole, even an overhead hole.

For small jobs with it, just uncap and squeeze a small amount out, just enough to get it to flow from both openings, scrape that off and discard, then squeeze what you need, scrape it onto a piece of cardboard or whatever, and mix with a stick. That uses a lot less than a nozzle, and doesn't waste a nozzle.

I really like the product for a lot of small stuff on the boat. No mess, no sticky paper cups and sticky pumps and powdered thickener all over the boat. Thick enough not to run but thin enough that you can actually wet out cloth with it (takes a little work). It does take a long time to go off, so you have plenty of working time. Warm it up if you want it to go off quicker, but don't get it too warm or it will start to droop. The thickeners do things that you can't achieve with other thickening agents, in my experience.
 
BruceK said:
This is a method I saw at my local hardware chain, I see the sense of it but it depends on the plug getting a good grip on the core,and I suspect that won`t happen.
Appreciate the quick and detailed replies, the 2 stage epoxy fix makes a lot of sense.
Interesting, this thread already shows up on Google search.
Click to expand...
Hi Bruce,
The Bunnings fasteners are more appropriate for a solid wood hole, not yours where you have a top and bottom layer of glass with "mush" in the middle.
The method described earlier - an allen key to allow you to clear put the foam from between the layers out to a diameter of say 2cm is a tried and true method - try to scrape the bottom and top layers of foam clean of foam - dont enlarge the existing hole. Pour in unthickened epoxy to pre coat the surrounding foam and the top and bottom layers of glass. Suck this out after a bit (but not long enough for it to go off) with a syringe then pour/syringe in thickened (but not too much) epoxy. Once its set, drill your screw hole and you are away. This method, because it solidly joins the top and bottom layers of glass will cope with a through bolt and nut
 
Amazon here has it available for delivery on this Saturday.
 
Thanks. Maybe discontinued in Australia. I’ll phone a supplier here, weird, they list spare nozzles but not SIX10 itself.
 
If you can’t get it then get a lare syringe and mix up some thickened epoxy and use the syringe to inject it.
 
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