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“Heaven is under our feet as well as over our heads.”

-Henry David Thoreau, Walden

Guy lines and guy line tensioners come with many tarps and tents.

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Guy Line Basics


We've seen them used incorrectly and recently had someone ask how they should be used. Guy lines attach to loops on a tent’s rain fly and are then staked into the ground away from the tent. The guy lines keep the rain fly away from the tent body to prevent the potential for leakage. Guy lines also increase the tent’s structural stability so that heavy winds and winter snow loads don’t cause the poles to flex excessively and ultimately snap.

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.

how to use tent guy line tensioner

Most well-designed tents have Velcro (hook and loop) loops on the underside (on both sides for reversible rain fly) of the rain fly, found directly beneath the guy line loops. These Velcro loops secure to the poles and provide the fastening between the guy lines and the tent’s pole structure. Remember that when increasing stability, guy lines are most effective when they reinforce the poles and the rain fly, not just the rain fly.

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. Factors such as sunlight and rain can cause the rainfall material (tarps, too!) to draw tight or sag. Sunlight heats and draws the material tight while rain can cause the material to sag. So, keep an eye on it adjust as needed. I learned the hard way with one of my favorite tent flys, the EUREKA! TCOP (Tent, Combat, One Person) and sunlight. I pitched the tent and cinched down the rainfly and didn't leave enough slack for the drawing of the material in the sun. I ended having to reheat and press back down some of the seam tape.

tent guy line tension mccarthy hitch

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.

Many of these knots have really fancy names that can be troublesome to remember. I've found that it is far more important to remember how to tie the know than know its name. Amazon has more books than you can count on how to tie knots.

In all honesty, the best way to remember how to tie these knots and use the guyline tensioners is to get out and tie them. I believe that you'll find that many of the knots used in this article for tents and rainflys can be used in many other applications such as tying down furniture in a truck, tying down a kayak, and so many more.

truckers hitch

Another simple way is use a trucker’s hitch, easy to tie and tension when needed.

guy line tension

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

bowline knot guy line

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