stripped fiberglass screw holes

[Nonchalant1]

I have about a dozen screw holes in the fiberglass gunnel used in mounting the stainless rub rail on my 53my that have become stripped. I tired the next larger size screw, but it doesn't hold. Is there a good way to fix the holes so that they will hold the right size screw again?

I was thinking of putting two copper strips the size of a match stick in the hole with 5200, and then the screw. Maybe the copper strips will be pressed hard enough by the screw to hold on two sides and they'll press the screw threads into the fiberglass on the other side of the hole?

Thanks,

Doug Shuman

 

[Genesis]

Inject the holes with epoxy thickened with alumina to the consistency of a paste, then re-drill.

 

[mike]

FWIW, depending on the year of your boat there may be a wood backing strip into which the screws are fastened. Therefore to achieve sufficient epoxy filler adheasion you need to saturate the backing strip with a penetrating epoxy. Follow by a filler such as already mentoned or use Marinetex. Prior to back filling with epoxy, drill out the origional hole large enough to assure sufficient margin so when filled, you are drilling the "new hole" into the epoxy and not the wood/epoxy interface.

 

[MikeP]

Here's a handy reference to using epoxy in the manner you are considering, it basically duplicates the previous replies:

http://www.wessex-resins.com/westsystem/projects/otheruses/hardware/epoxyanchors.html

(lots of other good info re epoxy use on the site as well)

But I must admit that I have personally never had any luck with epoxy holding load-bearing screws. You might want to look at this as well:

http://www.yachtsurvey.com/Screwit.htm

 

[NAN-PO 41]

I have also not had great success with epoxy holding screws.
Having had the surprising experience of a bow rail pulling loose because it had not been properly installed in the first place, I would not consider fastening one without through bolting with a proper backing plate. That being said I realize that it could become nightmare of a job and make for a tough days work.
SOMEONE GOING OVER THE SIDE AND ENDING UP BETWEEN BOAT AND DOCK IS NOT WORTH FIXING A RAILING MOUNT THE EASY WAY!!!
O. K. I'll get off the soapbox now. Fred

 

[Genesis]

The OP was talking about his rubrail, not the bow rail.

Agree with you on the bow rail - those mountings have to hold, otherwise someone could get hurt (or worse.) The rubrail screws don't (normally) take large loads, as the lever arm is short (millimeters at most) .vs. a bowrail stanchion which has the entire height of the rail as a lever.

 

[Nonchalant1]

A guy at the marina said to get the right size and length stainless pop-rivets and 5200 them before and after. I don't like the idea of pop-rivets for something like this. I'll try the drill-out and Marine-Tex and see how it goes.

Doug

 

[jim rosenthal]

Basically these screws were put into a fiberglass sandwish, essentially, when the boat was new- they go through the hull-deck joint which is sort of like a shoebox lid. So what you are trying to do is reconstitute what was there to start with....
I would probably seal the hole with unthickened epoxy using a small brush, and then fill it as Karl suggested- epoxy thickened with aluminum powder. (like WS barrier coat additive). After it has cured, redrill it and put a new SS fastener in.
Frankly, the stainless rub strip is not the best designed part of a vintage Hatteras, although they look nice. There is nothing there to cushion the blows that the area will endure from pilings, etc. Sooner or later the FRP structure under it will be fractured. I think the screws get loose from being hit directly by pilings and driven further in, which pulverizes the laminate around them and results in their having nothing to thread into that isn't basically crumbs. So....
..when I last did this, I did it differently. I drilled the hole so that the fastener just threaded in, and then filled the hole with 4200 and screwed the fastener in. They are tight in there, but I am hoping that the flexible 4200 will provide some give when they get hit again. If that doesn't work, I may try Flexbond- a two part epoxy which remains flexible when cured.
If you look at later Vikings, they do this area in a better fashion- there is a thick flexible vinyl rail which is held on by recessed screws, and then the SS rubrail is screwed to that, but NOT through to the fiberglass structure. It doesn't look as nice as a Hatteras, but there is give to it, and the frequency of repair is far less, I think. To duplicate this on one of our boats would be expensive and it would look unusual when done, but I wish ours had a better system- having had to repair impact damage several times over the years.

 

[OVERSPRAY]

Here is another option. I have never had good (long term) luck with filling a stripped screw hole with epoxy and having it hold. Especially on a maintenance area. What I have done however is flip the rub rail over end to end and redrill new mount holes, this will give fresh glass to screw into. the chances of the holes being in the same spots are slim. Yes you will be drilling new holes and leaving the old ones underneith, so you will have to fill them in with epoxy or sealer. My boat does not have a wood backing plate at the hull/deck joint. They just ran the rubrail screws right through the glass. It held fine for a long time but years of pilling rubbing by the previous owner took its toll. I reglassed over all the rub rail holes for a fresh mount when I resurfaced my toe rails but I was re gelling anyways so it didn't matter.

 

[Nonchalant1]

How about those oversize screw-in plugs with a smaller thread size hole tapped inside? I know they work fine in automotive applicatiions. You drill out the hole LARGER, tap it for the bigger size plug, screw the plug in, and screw the screw into the tapped hole inside the plug. Would that work on fiberglass?

Doug

 

[OVERSPRAY]

Or you could allways just pound a plastic drywall anchor in there if you really want to butch it up

 

[Nonchalant1]

I did try a "heli-coil" today. It won't hold in the fiberglass. What did hold is the next size larger stainless wood screws, which I put in with a shot of 5200 and a lot of torque. They seemed to hold very tight. However I discovered 3 screws that had previously been replaced with big pop rivets which had subsequently had their heads pulled off. I'll drill them out and go for the stainless wood screws there too.

Doug

 

[TedZ]

This is going to seem a lot lower tech but i have used it on hundreds of screws in fiberglass and never had a problem.

There is a wood skewer that is sold in supermarkets in bundles. I'm not sure what the wood is but the grain is lengthwise and very "stringy" for want of a better word. As a matter of fact they are hard to break period and never break cleanly.

Anyway, dip those in epoxy, put them in the holes and cut them clean with a razor knife. Don't use the point, i.e. cut an inch off before you start.

You can drill the skewer with a very undersize drill but i just reinstall the screws with a touch of 5200 under the heads for sealing.

Works every time.

Ted

 

[doc g]

Tedz,
Bamboo skewers!!!!

 

[TedZ]

Yes if that is what they are...they probably strip it out like locust as the grain is so straight and then point it.

Ted