Thanks for the reply Fubeca.
I am going to make the concave part in one piece and the flat part in another. Then I will wrap them individually and put them together.
Like this:
Kinda..Maybe. I think it will work. The flat part will be about this size & shape to act as a support platform for the back 4 feet. It will also provide a fair bit of "anti spread" strength at the caps mid point. Over engineered?
Probably
.....it's kinda my thing.
I have changed the back of the concave part to have a 3" flat area on the aft end. I did this for ease of construction. I couldn't get my head around making it taper flat and still have something to nail everything down to. This way I can make the last "rib" out of a chunk of 2x4 for my final tie in.
I don't think it will cost me any efficiency at all.
Status Report:
I have the ribs all made, I plan on making the flat parts for the ribs to rest on tomorrow and putting together the flat deck too. I'm using 1/2" OSB for everything so far to keep the weight down. I have 2 sheets of 1/4" CDX for the skin, it's pretty rough but it was half the cost of anything else they had at the lumber yard which I would consider using. I may just need to plaster on a few glops of Elmers wood filler to fill in some knots in the CDX, or not. I don't think they'll be seen through the shrink wrap. I have taken some pictures which I'll post when I get the frame together and before I put the sheeting on.
I changed the shape of the top profile of the cap, I was going to make it rounded to match the roofline of the truck, but since I have a fairly pronounced aero shape when viewed from the side I thought trying to get the 1/4" CDX to compound bend would be difficult. So now I basically have a 2 foot wide flat area on the very top of the cap which will go from stem to stern. On each side of that is a 1 foot wide flat spot that tapers for the final 3 feet, it is about 10 degrees sloped in relation to the 2 foot wide area. I figure it'll make the application of the sheeting a cinch and still match the profile of the roofline within 1/2 inch or so. See the illustration of the rib profile for a better idea.
Thanks for your input. I suppose I can keep a bunch of the Black Poly in my truck and if it gets too loose & baggy I could always cut new pieces to overlay and slap staple the crap out of them, it would look like hell but would work.