If you do a bit of research into hammock design, there are hammocks with spreader bars where the bottom of the hammock is below the points of attachments and the spreader bars. This puts you, the sleeper, the CG is lower and much more stable. There is a book on hammocks called the Ultimate Swing and it explains all of this. Having the spreader bars on the same level as the base of the hammock puts the sleeper in a very high cg configuration and there is a lot of movement. Think of your swinging cooking appliances on the boat. Where are the swing points? They are above the burner and pot of food. The same thing applies when designing a hammock with a spreader bar. The spreader bar is a good idea as it keeps your shoulders from becoming compressed.
