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Old 19-06-2018, 06:08   #1
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Fix screw stripped in gel coat/fiberglass

I have some non-structural screws in different places of the exterior of the boat that are stripped. Most of them are canvas post fasteners and some for gas prop lift supports. Wondering how people fix these in the fiberglass/gel coat.
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Old 19-06-2018, 06:27   #2
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Re: Fix screw stripped in gel coat/fiberglass

Take off the fixture/hardware, drill out the hole a size or two larger, inject/fill/fair with epoxy, and redrill to proper size for the screw. Use a bedding compound/calk and reinstalling the hardware.

The hardware is probably undersized, but that's not uncommon for bimini feet and gas struts on some boats. If it's possible to thru-bolt the hardware that always gives a better result than screws.
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Old 19-06-2018, 06:31   #3
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Re: Fix screw stripped in gel coat/fiberglass

Best way is to replace the screws with bolts that go right through, with backing plates.

Second best way would be to drill the holes a size larger, and fill with epoxy thickened with colloidal silica. This is stronger than the fiberglass. Drill a hole slightly smaller than the screw, and put the screws in while the epoxy is slightly soft, so you cut a thread in it.
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Old 19-06-2018, 06:45   #4
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Re: Fix screw stripped in gel coat/fiberglass

Without seeing it it is hard to tell.But the first thing I try with any stripped screw is putting some valve grinding compound on the head.It's abrasive and helps you get a little extra grip on the fastener and works more times than not if used when it first shows signs of stripping.It is one of those cheap oldschool tricks that just works and is cheap to have on hand.


After that it is usually vicegrips but you have to be careful around gelcoat.


Another trick i use often is i have a set of lefthand twist drills.I use them to drill into the stripped fastener and at times I get lucky and the screw/bolt will walk itself out.But for the stuff you described I doubt I'd use these but still worth having on board ;-)


Chances are it's going to be vicegrips on what you mentioned.But if you can get it to come out a hair it'll let you grab onto it without doing more damage.


Oops,I thought he was trying to remove stripped screws ;-)
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Old 19-06-2018, 07:15   #5
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Re: Fix screw stripped in gel coat/fiberglass

Thank you very much for the quick responses! Very good advice and much appreciated.
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Old 19-06-2018, 08:10   #6
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Re: Fix screw stripped in gel coat/fiberglass

If all else fails, drill off the screw head, then get a piece of tubing (Stainless, but brass will work too) that has an I.D. just over the diameter of the screw. Notch the end a little to make 'teeth' then chuck it in a drill and cut a plug around the screw. Then you can do as suggested above, fill with epoxy and redrill for a new screw.
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Old 19-06-2018, 08:16   #7
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Re: Fix screw stripped in gel coat/fiberglass

Quote:
Originally Posted by Suijin View Post
Take off the fixture/hardware, drill out the hole a size or two larger, inject/fill/fair with epoxy, and redrill to proper size for the screw. Use a bedding compound/calk and reinstalling the hardware.

The hardware is probably undersized, but that's not uncommon for bimini feet and gas struts on some boats. If it's possible to thru-bolt the hardware that always gives a better result than screws.

^^^This is the correct answer. I would add that in addition to the classic "drill and fill" technique (see Don Casey's books if you do better with diagrams), bolting with sealant in the threads (it "crawls" up the threads to make a seal under the head as you bolt it down) with either a fender washer or a sealant rimmed backing plate in fibreglass or aluminum to spread the loads (definitely on winches, for instance, less so on fabric snaps) is good practice.
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Old 19-06-2018, 20:42   #8
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Re: Fix screw stripped in gel coat/fiberglass

Are the canvas fasteners the usual screw stud as pictured here?
Dot Fasteners

If so get some studs without screws, some #6 x 1” flat head machine screws, and some #6 Well Nuts. https://www.bestblanks.com/sign-stan...KZyfD_BwE#2353

If I recall correctly the od of the well nut is 5/16”. Drill the hole out to the diameter of the well nut, shove the well nut into the hole and fasten the stud on top of the well nut with the machine screw.

I’ve done this several times and never had one fail. It is also pretty water tight as the rubber seals the hole.
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