Guyline
Tension a tarp or tent so it stays drum-tight in wind, using a trucker's hitch.
Drum-tight in wind
A tarp that flaps is a tarp that rips. A trucker's hitch on each guyline lets you tension it until it's tight as a drum — and re-tension in ten seconds when it rains and the cord stretches.
What you need
cord 4–6 lines of 3 mm reflective cord knots trucker's hitch, half hitch stakes 6–8 pegs
The build
Stake the corners, tie a trucker's hitch in each line, crank it down, and lock off. The 3:1 purchase means your body weight is more than enough to make the ridge line sing.