Drilling hole in fiberglass

[Yellow Boler]

Originally Posted by Lyndaleen

How do you mount something like a rock guard when the only thing to screw into is fiberglass? If I drill a hole in the fiberglass and bolt a bracket, what kind of drill bit? Or, is it better to use something like gorilla glue to glue a bracket to mount the rock guard?

My rock guard is mounted on the frame.

[Casita Greg]

Originally Posted by Shullj

All the rivets in my Casita are aluminum, including those installed in the factory. I would certainly stay away from carbon steel or galvanized rivets. Also the tech at Casita advised me not to use screws as they can cause the fiberglass to crack. Dow silicone (RTV) is an excellent sealant and can be found at any hardware store.

That "tech" doesn't know squat. There are two reasons why trailer manufacturers use pop-rivets instead of good stainless steel machine screws and nuts. Price and Convenience. They are used because they are cheaper and quicker to install. That is absolutely total BS about screws causing the fiberglass to crack. I've worked on many trailers and RV's, and long before that, for many years on boats. The marine manufacturer's, and particularly those who make fiberglass boats, have been using stainless steel nuts and bolts for over 60 years now, because they are far superior to rivets, And I can tell you that boats are subjected to much harsher environments, and to more stress from pounding, twisting, slamming and torquing than any travel trailer will ever see. They use nuts and bolts in fiberglass boats for their strength, where rivets would perform dismally.

[jn3521]

To avoid gelcoat chips when drilling holes make sure to flip the drill into reverse and burn through the gelcoat then flip it forward.

Also as someone stated, if you are adding weight and hangiing something you need a solid backer board or the bolts will pull through. I have done it for my boats in the past.

[Darlan]

I'm planning to install a cover myself in the future, the advises of who did the reno in my Boler; are: use SS one part rivet (there are others that have two parts, tent to let water pass); use a board on the inside pushing hard into the section you are drilling; drill at fast speed and supporting with the other hand the drill toward you, so it doesn't GO once it brakes through; just stop once you feel it broke the inside layer.

I guess it requires a bit of skills, and patience, and care, and...

good luck

[Casita Greg]

I would advise not to use stainless steel rivets because, unlike machine screws and nuts, you have no control over the "pop" point of the rivet. Machine screws can be tightened to a set point by you to achieve the proper tightness. Stainless steel rivets require much more compression before they "pop". If you're going to use rivets, use the aluminum ones.