Building Truck Rack

[EKlem]

I was wondering whether any of you have any experience with building a rack for your truck. The purpose of the rack is going to be to haul both sea kayaks and whitewater kayaks. The truck has a cap on it(it has been structurally compromised due to the weight on it which is the reason that I am building a rack) and the cap will stay on full time.



My real question here is what size and thickness of tubing to use? The rack is going to follow the general design of ladder racks made for going outside the cap although with a few key differences to accommodate a lot of kayaks. I have drawn up a design in Solidworks (a 3D CAD program) and used FEA to examine the strength. Given a load of 500lbs and a 4g bump, the rack has a safety factor of 5 which seems like plenty to me since a 4g bump is pretty darn severe. The tubing that I have designed it with is 2"X2" 14 gauge square tube. I want to go with square since it will be a lot easier to do all of the weld joints with since I can cut all of the angles on an italian band saw. In the experience of anyone who has built something like this, is this tubing heavy enough?

 

[stg2500]

I used 2"x4" tubing when I built my headache rack a few years ago. I used 3/16" tubing, but that may be a little overkill for kayacs, though.

 

[JoeHutchinson]

I have built several kayak racks over the years so here are a couple of toughts.



Your pickup bed is tapered from front to back, keep that in mind.



14 ga tubing sounds OK . It is amazing how heavy a rack will get, so stay thin where you can. You are using a lot more science than I did.





Angle iron is cheap and easy to work with for a lots of side supports



How do you plan to fasten the rack to the bed ?????





Joe

 

[jwgary]

So you modeled it in SW, ran a CosmosWorks FEA on it and now you are asking if you did it correctly? If you are using Von Mises stresses you are already conservative, and you have a 5:1 safety factor. It sounds like you already answered your question. Just make sure that the welds are sound. 5:1 should also give you infinite fatigue life.

 

[EKlem]

Thanks for all of the replies. I think that I will go with the design that I drew up then. It should weigh about 120lbs so two people should be able to put it on. The way that I am attaching it to the bed is running two 6" wide sheets the length of the bed so that they stick out about 4". I will weld the uprights to the outer corners. I have a few bracing pieces to go underneath and stiffen things up. The reason for running this the whole length is so that I can stand on it for loading and tying stuff down (I will put some non skid on it). There are gussets everywhere there should be. I just wanted to make sure that no one knew of anything better.

 

[ENafziger]

Wow... I'd like to see pictures as you progress!

--Eric

 

[EKlem]

Wow... I'd like to see pictures as you progress!



--Eric

As the design, it keeps getting uglier but it is getting a lot cheaper. The original square tubes have been replaced with 2"X1/8" angle iron since it is a lot cheaper. The cost has been cut almost in half at the expense of looks, oh well. I wouldn't want the rack to look better than the truck (I guess it still will since it doesn't have rust holes). If I can figure out how to get a JPEG of the CAD model off of the computer I designed it on I could post it.



I tried MIG welding for the first time last night and wow that was great. I have done a lot of TIG and dabbled in stick and gas but I had never had access to MIG. I wish that I had discovered it years ago. A little more practice and some cutting and I should be ready to start assembling. I am hoping to start in another week or two.

 

[SBall]

Wow, 500 lbs load with 4g forces seems to be a rather high target to me. I've been whitewater boating for years and have built rack systems for my truck(s) over the years. I've seen some "West Virginia custom racks" built with 2x3's and Quick-n-Easy towers straining with the load of a half a dozen kayaks at a time.



Even if you are hauling two plastic sea kayaks, seems to me that a design load of 300 lbs would be adequate. I'd also suggest that your supports be designed to accommodate factory cross bars from Yakima or Thule so that you could use their rack accessories such as hull cradles, ski boxes, etc.



I've had great success with round stock and using the Joint Jigger The Ol' Joint Jigger, Inc. , to cut the ends to fit at the desired angle using a simple hole saw.



Good luck with your project and be sure to post pictures of your rack.

 

[EKlem]

I currently have a good old wooden rack on the truck but it just isn't up to the task. I pretty regularly transport 6 or more sea kayaks. Being a college student, I move a lot of whitewater boats around sometimes. The rack is designed to hold 12 whitewater boats which should be around 600lbs.



I have ordered all of the stock for the rack. Member LSchulz and I are both building one for our respective trucks. The first task for his is going to be to transport 15 or so whitewater boats to the Salmon River in Idaho and back.

Wow, 500 lbs load with 4g forces seems to be a rather high target to me. I've been whitewater boating for years and have built rack systems for my truck(s) over the years. I've seen some "West Virginia custom racks" built with 2x3's and Quick-n-Easy towers straining with the load of a half a dozen kayaks at a time.



Even if you are hauling two plastic sea kayaks, seems to me that a design load of 300 lbs would be adequate. I'd also suggest that your supports be designed to accommodate factory cross bars from Yakima or Thule so that you could use their rack accessories such as hull cradles, ski boxes, etc.



I've had great success with round stock and using the Joint Jigger The Ol' Joint Jigger, Inc. , to cut the ends to fit at the desired angle using a simple hole saw.



Good luck with your project and be sure to post pictures of your rack.

 

[EKlem]

Well, the rack is all built and installed. I ended up using 14 gauge 2" steel tubing. The rack came out pretty well and I am pleased with it. It definitely seems pretty rugged. I don't have a digital camera but maybe I can find someone who does so that I can post some pics.

Thanks for all the help.

 

[EKlem]

Here are some pics of the completed setup. These pictures are of member LSchulz's truck. I ended up building 2 racks, 1 for each truck. This is loaded up with 14 kayaks about to drive from New Hampshire to Idaho. Since I don't own a digital camera, I don't have any pictures of the one on my truck. LSchulz has a taller cap so I made his rack 4" taller than mine but otherwise they are identical.



http://thebiggreenbus.org/lucas/DSC_0295.JPG



http://thebiggreenbus.org/lucas/DSC_0296.JPG

 

[LSchulz]

Made it to Idaho and back, the thing rode great with 14 boats up there. Catches a little wind, but still got 15+ mpg at 80mph once we hit the plains...