I don't think any of the stuff at Joanne's is 1.1. I have made tarps with it (PU coated variety) but never a hammock. I would order some stuff from DIY gear supply or some such place that is specifically designed for that purpose. Lots of work to have it tear out. Keep at it, it will work. I made a DL hammock from the pattern on Scott's website that has worked great. My wife likes it so much, she is going to make three more for her daughter to have at work and take camping with her husband.
The World is my country, all mankind are my brethren, and to do good is my religion.