I got the shelter logic 10'x20'. By the looks of your poles they are the same. Good point on the double roofing. I'll probably just use the second tarp to wrap the boat....when I get to that point.I'm not sure which enclosure you have, but a thought... If you double the roof thickness, it may actually chafe and not last as long. Might be better to use one layer, but hang on to that spare in case the first blows out.
By the way I was looking over my plans tonight and have noticed that the transom is for 15" outboard, but it looks like most outboards in the hp area I'm looking at (35-50hp) are 20" shafts. Any recs on the best way to raise the transom when it's already level with shearline???
I was looking at Joel's low shear FS17 and REALLY like the rounded look. I may duplicate that here. I figure if Joel did it, I can't go wrong