My daily driver is a small BMW Z3 roadster. I like to do projects and go kayaking and other stuff that requires carrying fairly large (but not heavy) loads. These two facts quite frequently cause me problems.
While my wife drives an SUV, it's always inconvenient and often impossible to shuffle our schedules and needs around so that I can use her car to do what I want to do, especially since she refuses to learn to drive a stick shift.
After a recent bout of struggling with this dilemma (a 1967 Cadillac DiLemma? Always wanted to say that...) I decided to find a way to carry loads on my car.
My design requirements, in order of priority, were:
No damage to anything on the car
No modifications to the car
Secure and stable support of loads such as my kayak, a few 2x4s, etc.
Easy and quick install/de-install
Preferably fits in the trunk of the car
I looked at inflatable car top carriers, but they seem to me to be unsuitable for loads such as lumber, and also look like they could damage the roof of the car.
I also found a device requiring a trailer hitch ($350) and the device itself ($150) AND it would STILL require placing a significant portion of the loading on the roof itself - again, possibly damaging.
Since nothing commercially available seemed to meet my requirements, I (of course) decided to see what I could come up with. Following is the result of 2-3 days of sketching and beer, followed by an afternoon of building - with no beer. (NEVER drink and saw wood. There are better ways to get to meet your local ER medical staff.)
This design uses the roll hoops as a load-bearing structure and with minor modifications should work on any car with roll hoops or a roll bar - though I suspect few owners of such cars would deign to stoop to such plebeian depths as to use a home built device on their garage queen. :-)
Since I'm pretty comfortable with woodworking, I went with a wood-based design, though if you're a weldor (yes, the "o" is appropriate, look it up!) you could make this out of steel (which is how I started this design, and may go there yet).
I decided that working with the top down would make it much easier to design a carrier, and it would be an extremely rare occasion that I would want to carry a load in the rain AND not be able to use my wife's SUV.
I decided to use a 36" 1x4 sitting atop and bridging the roll hoops to support the aft load and 1/8" luaun plywood skirts in order to keep the 1x4 centered and stable. I would also need some sort of padding to protect the vinyl covering on the roll hoops.
The windshield would easily support the forward part of the load, though I would obviously need to make sure there was padding to protect the weatherstripping, and spread the load somewhat so as not to create a point-load which could deform the weatherstripping and/or trim.
Also, I would like to carry my cheap 30"x120" plastic kayak (yay for Wal-Mart!) without damaging it, so I'd want a means of supporting as much of it's bottom as possible while still being able to fit everything in my trunk when not in use.