By Michael Tharpe
Q: Why must tents be anchored?
A: Proper anchoring is the most important part of ensuring your tent installation is safe. Frame tents must be anchored to hold them down. Pole tents must be anchored to shape them and hold them up. A tent (whether frame, pole or otherwise) will not remain erect unless it is properly anchored to the ground.
Anchoring is accomplished by fastening one end of a guy (for example, rope, webbing or cable) to the top of the side pole or bracket, and attaching the other end to an anchoring device such as a stake. The correct size of the guy and anchoring device is vital to the safe and proper function of any tent. Key variables include the breaking strength and stretch characteristics of the rope or web, as well as the stakes’ breakout force.
When tents are designed, engineers use industry specific standards and safety factors that are predetermined by standards organizations and model code authorities. Local, state, county and other district authorities will determine which codes are used in your area. Many officials adopt one of the major building codes, and some add their own rules.
A good rule of thumb is to always stake to the design of your tent. Regardless of the tent style — pole, frame or tension — the anchoring power will be similar if such factors as leg height, overall height, and basic slope of the roof are within commonly used patterns.
The preferred method of anchoring is staking, but many companies ask about weighting a tent instead of staking. The most popular way to weight a tent is via the use of water barrels. Let me pose this question: When is a pound of water not a pound of water? The correct answer is when it is used as a dead weight. A gallon of water weighs about 8 pounds, which means that a 55-gallon barrel weighs approximately 440 pounds, including the barrel itself. So it would take three barrels to achieve the necessary holding power of 1,000 pounds, right?
Wrong! The friction coefficient of plastic is only 0.4, meaning that the force of weight in the barrel is only 40 percent effective, as the plastic can be slid along the ground fairly easily. This means that the water barrel’s holding power is reduced to less than 200 pounds. This would theoretically increase the number of water barrels needed to five in order to reach 1,000 pounds of holding power, but that’s not all.
In the staking process, the guy lines are attached close to the ground. When raised at a height of three feet, as they are with water barrels, the anchors lose about one-third of their holding power, which means that you will need one-third more barrels to achieve 1,000 pounds of holding power.