Hello again folks,
Sorry I haven't responded in a day or three. Been busy crimping and welding and hole cutting and spray gluing vinyl and all the other fun stuff that goes into actually finishing a build! Also just made a final todo list. They're all small things, but man there are a lot of them
I've been reading along but waiting until I had time to chime back in. I really appreciate the thoughts.
Jack, thank you very much for the Prolink info. I hadn't really looked into that can of worms yet. That is EXACTLY what I am looking for, solves the problem elegantly - gets the synthetic rope out of the sun, avoids winch hook theft, a shackle is more secure than a hook, all around looks great. It's a bit spendy but it's a specialty product and I really, really like it when you can solve something well, it is worth paying for.
In any case, back to panels, I fully understand all the thoughts about the perils of gluing down. But gluing down something in the channels on the roof, then using shallow mounting screws into that, doesn't float my boat. If you're going to glue into the channels THEN glue onto the stuff in the channels, might as well just glue the panels to the roof and eliminate a step, some weight, and an extra layer to bond. As far as a sheet of material in between - bonding aluminum, despite all manufacturer and adhesive recommendations and ratings, is non trivial, and I have a bit of experience there, we've built our entire van of aluminum and plastic. If I'm going to glue down, it might as well be the panels instead of a sheet of 5052. I want panels to stay on, bar none, take a beating, and not be able to be torn off. We absolutely, 100% positively, will thrash these panels and will hit them with hanging branches, perhaps hanging wires, and who knows what else. They will be dirty, they will be covered in bird shit and mud and grime and who knows what in between cleanings, and they will get rained on for hours per day, every day. I want the cleanest, strongest, lowest profile adhesion possible. I don't think screws are necessary, but I am fairly convinced that glue directly to the roof is.
I realize glue down is (relatively) permanent. It could take many blades and many many hours or perhaps many days to cut the adhesives should I need to remove a panel, but I've tested the panels well, they are well vouched for by the vendor I purchased them from (whom I trust quite well), and if there is an issue, we are going to be a long way from a replacement panel anyways. Instead, we'll move to alternator charging or 1 panel charging should a panel crap out. I'd rather have peace of mind and spend 3 days carefully cutting Sikaflex than I would worry about a multi-layer mounting system or screws and leaks in the roof and things getting torn off. It takes a bit of commitment to glue down. I have that commitment, I'm just not sure of glue yet. I sort of have "two best options" as recommended by various people who have succeeded in using the products - Sika 252 and the Loctite S30. I will call both manufacturers, we'll see what they have to say.
I assume (and it's a HUGE assumption) that it is easy to adhere to bedliner. There is plenty of texture there! But realistically, it is just an assumption.
I will do a test adhesion with a line of each adhesive on my roof to a panel soon. I'll clean and prep correctly, press them both in, anchor / clamp / insure good conditions for curing, and in a few days I'll try to rip them up or if necessary cut them off. I'd rather tear Raptor-liner off my roof, or risk tearing a panel now, and know what's going to work, than I would glue down and cross fingers that nothing can go wrong long term.
Again, if anyone has used Polyurethane flexible curing construction / roofing adhesives or any other adhesives to fix things to a Raptor-liner covered roof, or has adhered TPT backed flexible modules to their roof, I'd love to hear what you used and how it worked out! I've heard of people taping down with VHB type tape, but I don't know much about it, really. More reading for tonight...
Again, thanks all for the thoughts and I don't mind being called crazy/stupid/etc. I really believe in lots of research, lots of testing, then just going with the best solution, even if it sometimes is hard to reverse. I can, almost always, readily remove/fix/re-arrange what I need in the van. But there are things that will be painful to undo if necessary. Thankfully I'm confident in what I've done there, and thankfully beers and patience and tropical weather assuage the frustration of invariably undoing at least one of those things down the road.
Cheers all, I do appreciate any and all information shared!