1. To sink, settle, or droop away (from something). I hate the way my skin sags away in certain places. Just another wonderful perk of getting old, I suppose. Over the years, the dilapidated porch began sagging away from the rest of the house, until, one morning, it finally collapsed entirely.
2. In a boat, to drift continuously to leeward. With the rudder broken, we sagged away to leeward, completely at the mercy of the winds and the tides. I let the boat sag away south by southwest, intending to swing the sails around and take advantage of a clean line of wind to push us across the finish line.
sag away (from something)
to settle or droop down or away. The cloth sagged away from the edge of the table.