Not necessarily. If you install a ridgeline the hammock will not be at it's full 11' length. Most people start of with about 87% (or is it 83%? Brain cramp right now) of the total hammock length which is where they find a comfortable lay, give or take a few inches. In essence, you're looking at a tarp with a ridgeline length of around 9.5 feet. Here's the math: 11' X 12" = 132". Take 87% of 132 which gives you 114.84". Divide that by 12" = 9.57 feet.

I have a

MacCat Standard tarp (125" ridgeline) and I hang it over my 11' DIY hammocks with no issue.

I hope that information is clear.