What do mounting screws "screw" into?

[Sparklite]

We will pick up our Oliver this summer, and I'm always checking this page for future ideas. 

Sorry for this silly question, but I haven't figured this out yet.

I don't know much about working with fiberglass, by what are the appliances and hand rails screwed into? 

I can assume  the screw threads are not just biting into fiberglass, and there must be a mounting plate/nuts behind everything mounted to the fiberglass? 

Another example is the backrest on the LE. I cant imagine this is held in place with only the 1/8" or so of fiberglass and a "wood" screw. 

[John E Davies]

Welcome to the forum! Please fill out a signature, so we know a little more about your tow vehicle and trailer.

Any structural attachment, one that will have a lot of stresses applied to it, such as the entry grab rail or the outside door hold-open doohicky, has a bonded in place aircraft aluminum (same as the frame) backing plate for the screws to thread into. For example, all the solar panel mount plates are installed when the hull is made, even if you don’t order the solar option.

FYI you can mount stuff using self tapping screws right into the glass, as long as it isn’t heavily loaded. If you are concerned you can add a strip of 3M VHB tape to make it stronger. Or mount the item to a decorative plate, then stick that down with the tape, so, no drilling of the fiberglass. Some owners seem to be reluctant to put holes in their new $75k trailer, but that never bothered me very much😬

Finally, most of the stressed parts of the hull are not just a single 1/8” glass layer, they are two layers, separated by a fiberglass honeycomb core, or in the case of the front divider wall, a balsa wood core. The battery box floor is two glass layers encasing a 1/8” diamond plate aluminum core. And that is supported (or is supposed to be) by a heavy brace bolted right to the frame. It is uber strong.

Here is what a typical honeycomb panel looks like. (The steel disc is not an Oliver part.)

These are tough little trailers. Oliver still makes some production mistakes, but the basic engineering is most excellent.

John Davies

Spokane WA

 

[ScubaRx]

Everything of any substantial weight or having force applied to it has an aluminum backing plate molded into the fiberglass. Think awning or solar brackets. Also the fiberglass in an Oliver TT is much thicker than everyone else's. Whereas a Casita may actually be only 1/8", the Oliver is about 3/8" so lightweight objects can easily be attached by screwing directly to the fiberglass.

[Trainman]

I agree that backing plates are the way to go, I have even glued (fiber glassed) the backing plates to the back side just for added strength. May not be so important on a trailer to do this, but on a boat I felt it was need because boats don't ride like a trailer would. 

trainman