Erez & George,
I have experienced some pretty severe weather since I built the shed. I micro-burst this August pulled the staples out of one corner of the plastic - it took me 5 minutes to put in as many staples as I should have started with around the bottom.
It has been dinged with black walnuts from 40' above. Thunderous noise, and a dent in the plastic were the worst of it.
We have had a few feet of snow this winter. It piles on top and the ends of the shed sag a little (inches) toward the middle. I have gone out to clear the snow (slap the top from the inside so it slides down the sides) because of an unanticipated problem. When it warms up, and there is snow on the plastic, water condenses inside the shed and drips onto the unfinished boat.
Some unanticipated good points: the grass I built the shed over is thriving in spite of not being directly watered since May. I wore a path around the boat, but the climate inside keeps it healthy. Its a little warmer than outdoors in the winter, and a little cooler in the summer because of the shade. How does it know which to do?
The strength of the whole thing is its flexibility. My kids crash into it and a rib bends then springs back.
I will take your advice to reduce UV, but I don't want to give up light inside the shed. I think I will just cover the boat inside when I'm not working on it. I won't have to worry about anything blowing away or being an eyesore, and I will prevent any condensation problems.
Thanks for the help.