I was thinking about this , and yes it hurt. If the optimum sag is 30°, then for a fixed length of hammock, shouldn't there be a fixed length of ridgeline to accomplish that sag?
Yes, yes, that does depend on exactly where you attach the ridgeline, and others may prefer more or less, but assuming you are attached exactly at the end of the hammock, there should be a very small range to accomplish this sag. No?
I am poor at my arc length and tangent math. Are there any math wizzes out there who can assist?