5200 vs Screw Holes

[rwells36]

Installation of solar panels on the top of my helm call for z brackets as a tie-down method. Question is which is better? 5200 (permanent) 3M adhesive or screws and their associated screw holes (probably 50 of them suckers).

[Bill O]

Ok I'll be the first to bite on this. Since I tend to overbuild everything I would go for mechanical fasteners through bolted with a backing plate as the 5200 alone would only bond to the gel coat or surface layer. Under the z brackets either use butyl tape/your favorite adhesive to stop any water penetration that may ruin your headliner.

Once those panels are on the main hardtop I doubt you'd be going up there to secure/remove for storm prep, so IMO go for the overkill and through bolt them.

Cheers.
Bill O.

[denverd0n]

Agree 100% with Bill O.

[barnakiel]

I have installed light elements with 5200 solely.

You must look at how the forces are applied to the bond. The only 5200 bond situation that is iffy is in peeling (force arm angle). In compression (separation) and in shear 5200 delivers very well.

You will find the bond strength in the data sheet - for various materials. Bond to gelcoat is fine. Bond to polyurethane painted surface will depend on how well the polyurethane paint sticks to the surface (often, it hardly does).

b.

[john61ct]

delete

[Cheechako]

Do not use 5200 as an adhesive only, use it with fasteners. While it can be tenacious sometimes, others it's not.

[UNCIVILIZED]

I've seen keels bedded in the stuff not drop off, despite their bolts being removed, due to the adhesive ability of 5200. Quite entertaining!

[senormechanico]

A friend of mine with a powerboat mounted 3 180 watt flexible panels to his boat's hardtop using 5200.
He weighted them with several 5 gallon buckets of water over thin plywood and left it that way for a couple of days.
That was a few years ago, and they've stayed tight through some horrendously windy weather.

[john61ct]

Flex panels completely different story from standard rigid framed ones.

[rwells36]

Originally Posted by john61ct

Flex panels completely different story from standard rigid framed ones.

4200 and bolts with backing plates is ideal. However, screws without backing plates is my only option due to limited access to the cavity of the helm's hard top.

[john61ct]

Rivnuts or similar, maybe Plusnuts into composite shell.

Stainless of course.

I would use to fix a one-time sheet or generic mounting rack, then panels to that, allowing for completely different replacement panels, without worrying about different holes pattern.

[carlheintz]

I'd vote for 5200 + screws. Can't overbuild it.

[Cadence]

I'm an advocate of todays chemical bonds however removal may be problematic if necessitated in the future.

[davil]

here is another way using only adhesives in the absence of backing plates.
5200 provides strength more likely superior to any mechanical fastener ,since you cannot use backing plate I would more likely replace the screws with wooden plugs soaked in epoxy.
Just drill as many holes to your heart's content,the hole just a hair oversize to diameter of plug/dovel,then soak the plug into a container with the epoxy mix,drive it in, it will be waterproof and when cures is structural component,just finish sanding or dremel the tops.

David

[thruska]

Lots of conjecture here.
But we don't know what you are attaching to what ?
How big and how heavy are your panels ? 50 bolts or screws?
Also consider that depending on your panel , you will have heat generated on the backside of the panel. So if you glue the panel down without venting you could invite early demise of panels or other issues under that panel on your boat.
Pictures are worth a thousand words...