There have been a couple threads for PVC racks recently. Took awhile to upload pictures. Here's mine.
Click on the photo and it should take you to the gallery where you can see more info and photos of it.
Looks like it should work well.
Don’t trust PVC
I don’t trust PVC in any application that requires strength. PVC can bend or break unexpectedly.
PVC racks
Looks great.
However, PVC isn’t a material that should be used for a rack. It isn’t designed for the type of stress that will be encountered on the road. A major weakness would be in any Tees, joints, or els that are glued together with PVC cement. These will be weak points that may fail in use.
Your kayaks and the life of the guy behind you could be in danger.
Hmmm
I have to agree with Jerry and Dave - I wouldn’t use PVC for this application.
It isn’t Thule or Yakima - FAIL
Dear pirateoverforty,
I see the naysayers have already beat me to it.
Your rack should work fine for many years, schedule 40 pipe is schedule 40 pipe be it titanium or plastic. If it is solidly built it will stay together for a long time, period.
Regards,
Tim Murphy AKA Goobs
PVC has no UV protection
so degrades easily and quickly when exposed to the sun!
The idea sounds ok, to an extent.
BUT, i’d switch to ABS and maybe reinforce the stress points with an internal pipe.
Yeah, i knew there would be naysayers
But the PVC does not take any stress, other than the weight of the boat and static down pressure, which 2" sched 80 is more than capable of taking. The boat is actually strapped to the truck bed, no lift is passed to the rack.
Not shown in the pictures but at highway speeds I would also use bow and stern ties, just like I do when using Thule J cradles on my SUV for the kayaks, in case a strap broke.
truth about PVC pipe
I used to work as a sales rep for one of the major PVC pipe manufacturers and also installed thousands of feet of it as an electrician. There is documented effect on impact resistance to PVC with UV exposure. Here is one maker statement on this:
http://www.nacopvc.com/c/technical-info–forms/the-effects-of-sunlight-exposure-on-pvc-pipe
NOte they recommend painting it (Rustoleum makes PVC specific spray paint, I think.)
However, Carlon (the company I worked for) makes the following statement below for their UL listed electrical PVC. They also point out elsewhere that only their schedule 80 is rated for hard impact resistance. If I was going to make such a rack I would use Carlon schedule 80. (it uses the same fittings as Schedule 40 since only the ID changes, not the OD).
UV is an issue for all plastic products. Fortunately there are additives that are added to plastics to make the material UV resistance. Listed Schedule 40 and 80 PVC conduit utilizes these additives and are UV resistant. The sunlight resistance test is found in UL Standard UL651. Listed product will have an indefinite life period.
Listed Schedule 40 and 80 Conduit have been used in Florida for years including on rooftops. It is preferred along the coast because it is corrosion resistant. When used in an exposed environment where there are changes in temperatures please are sure to use enough expansion fittings.
Static vs dynamic
It is not correct to say the PVC is only taking static stress, i.e. the weight of the boat plus compression due to straps. There will be dynamic stresses due to vertical acceleration (potholes, bouncing, etc) as well as torsional stress on the joints when speeding up, slowing down and cornering. Any of these stresses can exceed the static stresses - especially impact stresses when hitting a big pothole, which can be significant, exceeding static stresses by a large margin.
Re: the prior comment about materials, to say PVC and titanium are equivalent if rated to the same internal pressure is silly - otherwise you could make a rack out of sanitary glass piping with the same pressure rating.
Hockey Nets
I made a few hockey nets for the kids from the same pvc pipe material. They did not hold up well. I think it was UV damage. We left them out in the yard for a few years and then they started to crumble. Of course, as the kids got older their slap shots got pretty heavy which no doubt contributed to the demise of the net frames.
So my concern is long term durability if left outside.