Maybe you can build one like a big rig trailer. Use 3 or 4 inch rub rail on the sides, and I-beams for the cross members. Really simple, strong, and light weight. Obviously if you use thick I-beams, it will start getting heavy, but I'd say 2 1/2" by 1/8" thick I-beams wouldn't be too heavy, and you would only need 4 or 5 I'd think. This set up also allows for plenty of flex, I see hay truck trailers flex a ton yet they are super strong. If you get a chance sometime, take a look at a trailer, maybe get some ideas from that, just a thought.

 

So there's a variety of opinions on my design:
1) It'll be fine
2) It'll bend & dent
3) Redesign it.
That indicates to me I must be close to the limit on how light I can reasonably go.

So enough with opinions, I'm a scientist and don't do well with them anyway. I found an engineering calculator, figured out how to calculate the input values for the deflection of a cantilevered beam for various weights placed at the unsupported end.
120 lbs weight gives 0.06" deflection (approx weight on each ski of a snowmobile)
800 lbs weight gives 0.35" deflection (let's say I hit a big compression bump at 70mph, the ski weight is multiplied several times).

Those are the values for a single 1.5" 14ga. square tube. The deck has 5 (might go to 6) cross members, so the weight isn't all on one beam, and as such the deflection (read--flex) will be substantially less. I am no longer concerned about my frame structure. Gotta love math.

As for the stock bed being 12ga., it just isn't. It is 16 gauge at best. In the attached photo, the graduations on the tape measure are 1/16th's of an inch. Zooming in, I see 90% of a 1/16" for a thickness of 0.056". My 14 gauge deck will dent less than the stocker, or maybe as easily without the ribbing, big deal.




Ordered steel today. Cost of $366, LED lights were $130, ski glides were $80, $30 in hardware, figure about $30 in paint, done deal. I appreciate making me really think about my design. I'll post a few pics of the build in progress & of course the finished product. Then I'll report back if it folds in half and drops the $12k sleds on the highway

 

Just my opinion but I would figure in a 2x6 or 2x8 treated deck that is easy to replace if you wreck one. And they are cheap.

 

I want to see this thing done when is the scheduled(English accent) build?

 

I'll start this Saturday or Sunday. Should have it on by Thanksgiving.

I checked out some commercially built sled decks at the local dealership on Friday. They use 1"x2" tube throughout, and its laid flat for the cross members. I didn't measure wall thickness but it wasn't any thicker than 12ga, looked more like 14ga to me. Just further reassurance this will be OK for light use (not OK for farm/heavy haul use).

Definitely looking forward to the convenience of no trailer!

 

That took longer than I expected, but it turned out well enough. Made a few rookie mistakes but nothing too bad. I'll grab another pic with the ski glides, spare tire, sled hold downs, and bolt-on sides installed soon. The loading ramp stores under the deck.
My filler necks aren't too great, so I'll be doing something different or be forced to use a 6"x6" under the tire to fill up in a reasonable time. I used Herculiner on the deck surface and primed/painted everything else. DA sanded and wiped totally clean before application so I hope it all sticks well.
Resistors in parallel with the stop light circuit worked like a charm too.


Still had a lot of work to do at this stage, just doesn't look like it.

I'll probably add a storage box along side the ramp storage, fix the fuel filler, and maybe put expanded metal over the non-sliding portion of the rear window. Otherwise it's ready to go.







Bed liner was drying at this point.

As far as weight, the receiver hitch is 1/4" higher than with stock box on it. Stock box=285lbs
Tailgate=70lbs
Bumper=85lbs
Total=440lbs

I didn't weigh the flatbed just before install, but adding up steel weights/lengths it is 430lbs, and the weight isn't concentrated to the rear like stock so much.

I'll have my sled in it by the end of the day, might load up a buddies sled too and see how it rides.

 

Real nice!

 

Turned out pretty good. I like the look of a flat bed myself. I would be interested to see it loaded up with some sleds.

 

I like it! Great job!

 

I like it! How did you attach it to the frame? And... Why didn't you paint the receiver when you painted the bed?

 

Thanks for the compliments. I used 3" channel to make six 7" tall post mounts with plate welded on their bottoms, these were welded to the deck frame and use all the factory bed mounting holes on the truck frame with 1/2" grade 8 bolts. I didn't paint the receiver because the rest of the truck is rustier than it looks in these photos, so it seemed pretty useless.

 

Loaded up with two sleds. Drove 100 miles each way to go riding on Saturday. Felt good. 10mpg with a headwind in the morning and 15mpg with the tailwind driving home (55-65mph). Some body roll on corners but nothing uncomfortable. Truck sits nearly level with the two sleds on there and the front tank full of fuel (hitch dropped just over 3" in total and unloaded the truck has around 3.5" rake).








Pretty happy with this thing so far

 

A sway bar would be a good addition

 

It has both front and rear already, but it's only the 7/8" bar, a thicker one may be a good idea.

 

Just thought I'd give an update after running this thing through the ringer. It works great. It hauled 2 sleds twice a week most of the winter (lasts into May at altitude around here), mostly 80 mile round trips but one was 700 and we were loaded down. Towed a small trailer at times too.

Best part is 4x4 is rarely needed. If we need 4x4, we should just unload the sleds and start riding bc it takes 12" plus.

Since my last post on this, I added a lockable storage box next to the ramp storage. Works great for hitches, ratchet straps, chains, etc. and stays dry inside.

In addition to being great for hauling sleds, I hauled 2000lb of compost for the garden the other day (truck grossed at 5400 with tools, gf, and fuel on the way in & 7400 on the way out). Then this past weekend I was wheeling pretty hard, ended up fully flexing the truck so a rear wheel was off the ground on a nasty descent. All this and the flatbed is not bent, cracked, etc. The only repair I've made was fix a broken marker light wire.

14 ga. has proved to be a good "just right" plate & tube thickness IMO. No dents, and I even backed into a dead pine tree a couple months ago. . I can lift the rear of the truck with the Hi-Lift right on the flatbed's skirt too. So far, I haven't found anything I'd do differently except make the headache bar a couple inches lower. For the fuel fillers, I removed the extensions and now just have to reach under the truck to fuel up (this was a simple fix, and works for me).

Anyway, just wanted to post a follow up in case someone else had similar questions that I had when I started designing this.

Oh, and I did paint the receiver hitch