I was on http://www.owfinc.com and found this formula for calculating temperature rating:

How does this apply to hammocks? Hammocks get colder than tents right? Should I add 20 degrees or so? I don't want to sleep in less than 32 deg. F.

Two layers of .8 Primaloft would give me an Effective temperature rating of 36 deg F. Is that 36 degrees for real when it comes to hammocks?

ETR = 100 - (40x1.6 thickness)