Guy lines and guy line tensioners come with many tarps and tents.
Guy Line Basics
Guy lines will help keep you dry
Condensation normally collects on the underside of a rain fly, especially in wet, damp and cool weather. Condensation can find its way inside the tent If the rain fly sags against the (non-waterproof) tent body.
To prevent the condensation from getting in and wetting you and your gear attach guy lines to the loops around the bottom of the tent's rain fly and tension the fly away from the tent body, edges, and corners. Any well-designed tent will feature guy line loops around the base of the rain fly and midway up the fly along the pole seams to allow you to tension the rain fly away. Check the tautness of your rain fly from time to time, fabrics such as silnylon tend to sag as they cool.
Adding Strength to Your Tent
To increase a tent’s structural stability in heavy winds you should use guy lines. The guy line loops midway up the rain fly are designed to add the greatest strength to the tent, more so than those around the bottom.
For maximum effectiveness you'll need to set up each guy line so that it’s staked out anywhere from three to six feet away from the tent. I always drive the stakes into the ground at a right angle to the guy lines in order to prevent them from pulling out in heavy winds.
Guy line tensioning
From time to time you’ll need to tension and periodically adjust your guy lines.
One of the many ways to do this is to use a McCarthy hitch. By gaining a three to one mechanical advantage on the tent/rain fly you can easily secure with a slippery half hitch.
Another simple way is use a trucker’s hitch, easy to tie and tension when needed.
The easiest way is to use guyline tensioners, making tensioning and re-tensioning as simple as can be.
How to attach guy lines to your tent rain fly
A Bowline knot is one of my favorite ways to attach guy lines to my tent and rain fly. The Bowline knot forms a secure loop that will not jam and is easy to tie and untie, is reliable, strong and stable.
To tie a Bowline knot
- Lay the rope across your left hand with the free end hanging down. Form a small loop in the line in your hand
- Bring the free end up to and pass through the eye from the under side (the rabbit comes out of the hole)
- Wrap the line around the standing line and back down through the loop (around the tree and back down the hole)
- Tighten the knot by pulling on free end while holding standing line