Slack in Automatic Safety Covers

From time to time the question arises about the need for slack in automatic pool covers and how much is enough.  All automatic pool cover fabrics are made wider than the width of the track.  There are several reasons for this:

 1.  A cover that is too tight will pull against the tracks and will not operate properly.  A cover that is made too small reduces the life of the cover and mechanism, causing premature failure of both the fabric and the mechanism due to the added stress.

2.  All fabric shrinks over a period of time.  The amount of the shrinkage varies widely according to the weather conditions, particularly the amount of time the cover is exposed to the sun.  Slack is always added to the fabric to compensate for potential fabric shrinkage.

3.  In order to meet the ASTM safety standards, the cover must lie on the water, most of the supporting strength of the cover comes from the support of the water directly under it.
 
Each cover we manufacture is made with the slack calculated on the basis of the type of fabric, application, and unit.  Any other variables that may be brought to our attention are also included.  Initially, a properly sized cover will drop almost directly down from the track or deck to the water, with some folds & wrinkles as it crosses the pool.  Because each cover is subject to many variables, it is impossible to calculate the exact amount of shrinkage each individual cover will have, so an approximation is made based on our past experience.  Our slack formula is designed to give the cover and mechanism maximum life, as well as making the cover look as attractive as possible.