How to Measure for a Custom Safety Pool Cover

how to a-b measure your swimming pool
Once you’ve determined that you need a custom pool safety cover, the next step is determining how you will measure your pool to ensure a properly fitting cover.  The basic shape of your pool will classify it as either a “Type 1” or “Type 2” pool.

At In The Swim, a Type 1 pool is basically a modified rectangle.  Grecian, L shaped and bowed end pools would all be classified as a type 1.  They generally require very basic measurements.

A type 2 pool is more complex, and would include oval, kidney, lazy L, or free form pool shapes.  To ensure the proper fit of your mesh safety cover on a type 2 pool you need to use a method called A-B measuring.  The remainder of the post will discuss how to properly A-B measure for custom mesh safety covers.

Before you get started, make sure you have stakes, chalk, a 100 ft. flexible tape measure, pen and paper and hopefully another person to help record measurements.  The term “A-B measuring” comes from the fact that all of the measurements will be taken from 2 points, “A” and “B” which are staked outside of the pool, usually off the deck.

The first step is to establish the A and B points.  Place two long rods, stakes or large screwdrivers into the ground on one side of the pool, separated by at about 1/2 the pool length.  The invisible line between your A-B points must be at least 4 feet away from the pool and must not intersect the pool at any point.  Be mindful of areas of the pool that change direction or stick out further or closer to the line than other areas.
custom mesh safety cover measurements
In the kidney shaped diagram above, the areas of the kidney that bulge down towards the line must be 4 feet from the line.  It is OK for the line to be more than 4 feet away.  It is very important to record the distance between points A and B.  If you do not correctly state the distance between the two points the rest of the measurements you take will not triangulate correctly.

The next step is to mark and number your points around the inside edge of the pool in a clockwise manner, beginning in an area near the point “A” you have established. You can use strips of duct tape or use chalk. It may be helpful to write every fifth number on the tape, or in chalk below the point.

Points should be spaced at a maximum of 2 foot intervals and should be about 1 foot apart in tight areas.  Be sure to include all corners and direction changes as points as well as any obstructions (slide or diving board legs, ladders, hand rails, etc.) that are within 18 inches of the pool’s edge.  In the image below you can see the beginning stages of marking points around the pool.

how to measure for mesh safety covers
Once you have numbered all of the points around your pool, you can finally begin taking measurements!  Start by measuring and recording the distance from point A to point 1, then point A to point 2, point A to point 3, and so on – all the way around the pool.  You will do the same thing from point B, measuring to all points around the pool and recording them.  It is very helpful to have another person with you while you measure so you can call out the measurements for them to write down as you go along.  You can create your own chart as in the image below to record measurements, or you can use our custom safety cover measuring form found on our website.

measuring your pool for a mesh safety pool coverAfter you finish taking all of the A-B measurements, provide some check points of the overall length and width of the pool by choosing numbered points that are at the approximate overall length and width points of the pool. Measure the distance between the 2 points across the pool, the A and B points you created are not used for the cross-check measurements.  These measurements will be used as by the custom pool safety cover manufacturer to help validate the other measurements.

It is important for you to provide a diagram of your pool showing the shape, numbered points around the pool, and any obstructions around the pool within 18 inches of the pool’s edge. It is also a good idea to identify any areas where you have less than 3 feet of concrete extending out from the pool’s edge.  If there are any especially intricate areas or any areas where you feel uncomfortable with the accuracy of your measurements, sending pictures of the pool along with your measurements is always a good idea.

When the manufacturer receives your measurements they enter them in to a CAD (computer aided design) system that basically performs a slightly more complicated version of “connect the dots”.  They enter your measurements to create the points and basic shape of the pool and then connect the points to create the overall pool shape and size.  They will look at the diagram of the pool, any pictures you provide and your check points to make sure that everything matches, mathematically.

If at all possible, it is always a good idea to leave your A-B line and the numbered points on the pool deck until you know that the manufacturer is satisfied with your measurements. Sometimes the manufacturer will request additional check points or ask you to re-do certain measurements. If you do not have the original placement of the points and your original A-B line, you will have to start the whole process over (and that would just be too much fun!)

Hopefully you are now comfortable taking the measurements needed for your custom safety pool cover.  I think you’ll find that if you take the process one step at a time you will have success with it in the end.  If you have any questions please give us a call, we have experts on staff that would be glad to assist you!  Happy measuring!

Jackie Wolski
InTheSwim Staff Blogger

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