Repairing bimini top mount screw holes

Skuza

Skuza

Well-Known Member
Nov 1, 2006
1,458
Lake St Clair, MI
Boat Info
400 Sundancer
Engines
7.4L Horizons
What is the recommended way to repair screw holes that have had the screws ripped out?
Over the winter I wanted the bimini frame left up due to past minor damage from the shrinkwrap guys taking it down. Well low and behold this winter was extra snowy and the weight of the melting snow must have been too much for one of the mounts. It ripped the two screws right out of the radar arch on the aft bimini. Luckily it didn't bend the frame or chip the fiberglass beyond where the mount will cover. My thinking on repairs is either drill out the hole and then epoxy a wood dowel into the hole OR just epoxy the entire hole up. Then redrill the holes and screw the mount back in. I'm planning on doing this a month or so prior to launch just to give the epoxy or whatever I repair it with plenty of time to dry before drilling. I recall a certain toothpick method for ripped out snap screws and thats where my wood dowel idea comes from. Anyone for more ideas???
 
In the case where you could block the back side of the hole, filling with epoxy would be the choice. But since you can't do that, it sounds like this might be a job for G-Flex epoxy from West. It comes in a version with a thickening agent mixed in so it will behave more like putty.

I have not used G Flex, but have used gallons of the other West System epoxies over the years, so I have no doubt it will work as advertised.

Henry
 
If the hole is large enough to need a backing, take a small piece of fiberglass cloth, saturate it with West Systems, then ram it thru the hole with a pair of needle nose pliers or forceps, then pull it back enough to hang in the hole. After it cures, sand off the surface and fill what is left of the hole with West Systems thickened with 407 or 410 filler.

If the hole is just a pulled out screw, then use Regular West Systems 105/205 epoxy thickened with 410 filler to the consistency of smooth peanut butter. 105 needs about a day to reach full strength. West Systems makes a mess that is hard to clean up so mask off around the screw hole or mounting bracket and use an old credit card to force the epoxy into the hole.
 
The holes are no bigger than 1/8" to 3/16" I'm guessing. So no go with the wood dowel idea? Maybe it would be better to not have a less dense material such as wood in the hole as opposed to completely filling it with resin or epoxy. The screw would have a harder substrate to bite into then? There is no easy way to access the backside of the area as it is on the aft edge of the radar arch about a foot in from the sides.
Thanks for the replies guys.
 
Using wood as a plug is not going to be a long term repair. Besides the obvious decay in the marine environment issue, a wood filler is just not strong enough. You can use a wood filler for something like a carpet snap because there is very little load on the threads, e.g. the occasional removal of the carpet. However because in this case the wood is just going to be a thread filler, the screw will pull out under load.

The bimini mount on the other hand is under a great deal of load from wind and the physical motion of the boat. A properly sized screw turned into the matching proper size hole in fiberglass will yield a fastening system much stronger than a screw in wood. The down side of the screw in fiberglass is that fiberglass is brittle. So the screw needs to go in and stay in. That is why screws in fiberglass need to be installed with some form of bedding to keep them from backing out.

Henry
 
Besides, you apparently haven't used West Systems epoxy that Henry and I recommended. Once bonded to fiberglass, you can't remove it with a hammer and chisel. It will hold screws, if you follow Gougeon Bros application guide.
 
Hey thanks again guys. The wood dowel idea I was putting out there involved completely saturating the wood dowel in epoxy and THEN inserting it into the hole. But my theory is that unless it is a hardwood once you drill into the dowel your going to be into soft unsaturated wood and the screw would not hold as it would if biting into cured epoxy. I see the epoxy is the better way to go. Just didn't know if the hole could be fille with JUST epoxy. I have worked with epoxy in model building and at work so it's not something new. Just havn't had the need to use any on the boat yet!
 
+ 1 for Frank's answers. :thumbsup:
I have some small holes that I was wondering how to fill, thanks for the advice. I was going to use the fiberglass patch kits from an auto parts store, but this sounds better. :smt038
 
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