Based on extensive research, I have learned that polyethylene (plastic/rotomold) kayaks should be stored on their sides to prevent warping/bending. I say extensive research because there is a lot of conflicting info on the web about what way to store these kayaks.
So, I’m planning to build a kayak rack to store my kayak on its side, against a wall in my garage. I plan to build L-shaped supports out of 2x4s and cover them with foam of some sort.
My question is, how many supports should I use? The kayak weights about 60 lbs with rudder, so 2 supports placed under the bulkheads is placing 30 lbs of pressure at those two points. Is two padded supports sufficient to prevent warping, or should I go for more (3 or 4)? Once I get this built the kayak will be strapped in place on the supports with bungee cords.
Thanks.
You are an engineer, right?
…IMO you have the basics right and may be overthinking it. I think that boats stored on their shear lines are fine with two reasonably padded supports.
Maybe if you stored a plastic boat on edge for so long that you couldn’t justify owning that boat you could have a problem. Otherwise I think that two supports will do the job.
Jon
Ok
I’m no engineer, just want to protect my new toy 
Take a look at
something Home Cheapo calls a “Heavy Duty Arm Hanger.” Cost about $5 each as I recall. Might save you some hassle if you like it. That’s what my boats sit on.
Plywood and 2x4’s
I just built mine yesterday and will get some pictures for you but here is the gist of it.
I used cardboard as a template to make sure everything would fit. Just fyi, I’m hanging two kayaks, a Pungo 120 and a Pungo 100.
I ended up with a near J shape. I traced the cardboard onto a piece of 3/4" plywood (I had it laying around otherwise I would have gone with 1/2"). I made 8 copies of my design, 2 sets of 2 for each kayak.
I then screwed an appropriate length 2x4 (mine were 20" long) onto my basement/garage wall so they were perpendicular to the floor.
Next I screwed one J on each side of the 2x4. I spaced these about 67" apart so they would span my cockpit. I still need to put some more small 2x4 spacers in a few spots but they are more than beefy. For padding, I am using double bubble insulation. If that doesn’t hold up well enough, I have some old wrestling mat material that will last. I realize it is hard to visualize but as I said, I can grab photos tomorrow if need be.
Tripper
A less intrusive solution.
Put 2 eye hooks in joists about the same distance apart as the bulkheads.Get a tie-down strap or rope,make a loop at each hook and hoist it as high as you want, on its’ side of course.
Home Dumpo
Measure how “high” your kayak is from keel to deck. Then go to Home Dumpo & get a metal L bracket that sticks out far enough from the wall to allow the height of your kayak on its side. They typically run $5-8 each, and come with foam on them which will protect your kayak. That’s what I’ve had both mine on for 4 years now. No marks. If you’re nervous, get some large size foam pipe insulation or a pool noodle & add an extra layer of foam. Two per boat, close to the bulkhead will be more than enough.
Just make sure you hit studs with the screws. Sorry if that insults you, but I’ve seen many accidents…
He’s no engineer
Engineers know that pounds is not pressure.
Anyways, two will be just fine.
http://good-times.webshots.com/slideshow/560539316UHCTKw
ladder racks
Just go to Home Depot and get a hook style ladder rack. I’ve stored many of my fishing kayaks this way for years.
2 supports are fine
My boats are too long to put in my garage, so I have them outside. But the racks would be the same. Here’s what I did.
http://outdoors.webshots.com/album/577063179QdUedI
Andy
The finished rack
http://img838.imageshack.us/img838/5673/dsc1137.jpg
http://img440.imageshack.us/img440/668/dsc1139v.jpg
Wooden L rack with two layers of carpet padding. Kayak is secured with bungee cords to each rack.
Here is what I did…
I can put mine on the sides as needed…
http://outdoorsmike.blogspot.com/2009/08/storing-kayak-part-1.html
http://outdoorsmike.blogspot.com/2009/08/storing-kayak-part-2.html
I would make some changes if I did this again but maybe this will spur some creative juices.