roof rails

[Tomhog]

Are the roof rails on the Concourse mounted with through the roof bolts or just surface screws, also how thick is the fiberglass on the roof, Thinking about starting a project up there. Thanks

[Blue~Go]

I believe they are mounted with just #8 "pointy" screws through the top fiberglass skin and somewhat into the plywood core sections they put there. The rail itself was, I suspect, meant to be mostly cosmetic. That said, some here have used them for carrying heavier items (via the many tiny twigs make a strong branch principle).

My worry would be either collapse or breakage, or if not that then water intrusion into the core due to the screws wiggling.

(But then I don't know what your project is anyway.)

BG

PS: Forgot to say anything on thickness. I'd estimate the top fiberglass skin is something like 3/16" thick, then the core something like 1", and the inner skin... not sure but inner skin is usually thinner than top skin in cored construction.

[Scott]

I'd estimate the top fiberglass skin is something like 3/16" thick, then the core something like 1", and the inner skin... not sure but inner skin is usually thinner than top skin in cored construction.

3/16" is a good approximation. I've measured it in many places, and it varies throughout the shell. Haven't seen anything under an 1/8".

[deppstein]

I think Blue is right about the surface mounting...and the "pointy #8' screws that secure the rail. That said, I did use that rail to mount my two sets of "high-clearance Thule feet" that hold cross bars that I use to carry our canoe (upside down, centered over the AC housing with the thwart removed. I believe there is a thread where this is discussed and where I posted some pics...if not (or can't find them), let me know and I will try to locate and send again.
Regarding the strength of the rails...all I can say is that I have logged well over 10,000 miles with the canoe up top (even across North Dakota--now that was some wind!) and never had any issues. Canoe is securely strapped to the cross bars and also tied bow and stern.
Other questions, let me know.

David

[Tomhog]

Thanks for the input. I was thinking of putting that small flat space by the ladder to use by putting a 36" x 24" by 6" high rail using marine hardware and adhesive. Planned on putting a dry bag up there to store some light weight items like the bbq and use some bungee cords to hold it in place.

[kdarling]

Heh heh. Naturally, I have an entirely different desired use for the aluminum rails:

I keep thinking how neat it'd be to attach a hose connection at the rear, and drill tiny holes all around the railing.

Then I could hook up my garden hose and easily wash down my Chinook, starting from its roof !

[chin_k]

If the pressure is high enough, you may be able to mist the Chinook, and not worry about turning on the AC all summer!

Seriously, I wonder if it is worthwhile to reinforce the pointy screws by replacing them with bolts and washers under the fiberglass. I won't use the rails for heavy items, but it is nice to know that it won't get rip out if I go over a bump.

[Blue~Go]

Seriously, I wonder if it is worthwhile to reinforce the pointy screws by replacing them with bolts and washers under the fiberglass. I won't use the rails for heavy items, but it is nice to know that it won't get rip out if I go over a bump.

If these were cleats or other hardware on a boat - or even load bearing hardware on the Chinook - I'd say a resounding yes. I'm all for backing plates and I've installed many. But given that it's basically an ornamental trim piece (albeit a large one), I'd weigh in on the side of no. That's not to say they shouldn't be re-bedded as a part of maintenance. And when I do that I very well may overdrill/epoxy fill and then either set the pointy screws in green epoxy or drill and tap (probably the former in this case). And also chamfer the holes which, if they are like the rest, are cracking some due to no chamfering.

But backing blocks would be a royal pain to do (because there is a liner there on the inside, plus the upper cabinets). They would also likely be stronger than the rails themselves, which seems kind of backwards to me. I don't like to make one part of a structure much, much stronger than the rest of it. Places I *would* put backing blocks are the ladder and the awning. Not that those necessarily need it because they seem to hold on, but I mean I would do those long before the roof railing.

For me, if I wanted to use the roof for something "structural," I'd likely install some sort of purpose-done rack/feet/whatever, and make it all of a similar strength matched to what I was doing with it.

That's not to say the ornamental rail can't be used for anything. Clearly it can and has. But these are my thoughts on it.

BTW on boats there are plenty of aluminum tubing structures such as for lightweight biminis and etc. But you just know not to put any stress on it. For rails or structures that you want to be able to grab, put things on top of, etc., they are generally stainless tubing (which is heavier and stronger) and then do have appropriate backing/fastening/etc.

[chin_k]

Blue, would you change you assessment if the rails is changed to more sturdy material and construction?

[Blue~Go]

Yes, I think so. For example (obviously the design would depend on what one wanted to do with them) if the rails were stainless, and the bases were through bolted and had backing plates, then they would be super strong. After all, being near the edge of the roof like that makes it in general a strong place.

That said, stainless is heavy (for up on your roof) and expensive. So, I'd likely just design something for whatever job I specifically wanted to do, vs. changing the whole roof perimeter rail.

If you want to get an idea of the parts available, have a look at www.sailrite.com They sell a wide variety of stainless tubing and the bases and joining pieces to go with it (for boats, generally). But you'll get an idea (they have good videos too). There is thinwall vs. thickwall, and 7/8", 1" etc. diameter. They also sell aluminum tubing and bases, but it's understood those are for applications that are lighter duty. For example, I have a canvas "porch roof" type structure on a boat that has an aluminum tubing frame and plastic bases. I know I can't "grab" the framing for support, and likewise I remove the canvas in windy conditions (and certainly for trailering speeds). Otherwise it would break. (And that's even with it through bolted at the bases.)

This all said, we do have members who are using the roof rails for various additional loads, so there isn't a set in stone kind of guideline. I'm just giving my thoughts on what I'd be comfortable with. But then too, when Chinook themselves put things on the roof, they did not use the rails. For the optional cargo box, it had its own mounts; the solar panel had its own feet, and in later years they had an optional roof cargo basket (not attached to the roof perimeter rail). That may have been simply location based, but I'd be a bit disappointed if they used the perimeter rail (on a factory job).