i too ran into the same problem with my first diy hammock. what worked for me, which is close to what jred does is start the hem and place it into the sewing machine and manually turn the machine until the needle goes through the fabric. this works as an anchor and lets you roll about 12" - 18" at a time. the trick for me was to hold the already sewed end with one hand and the unsewn end with the other and pull the hem tight. you have to more or less pull the fabric through instead of the maching feeding it, but after some practice it become very easy to do.