When making a new hammock and setting the ridge line I use two biners to connect to the hammock supports. I tie one biner on solid, and make a few knots in the ridge line at intervals that I think are "close" to being correct. The knots are larger than the tie area in the biner and jam there making it easy to change lengths until I get it right. When I hit the correct length I untie the unused knots tie it off at that point. Has worked well so far.