# formula help

On Thu, 24 Aug 2006 19:48:46 -0700, "Steve B"

When I have the FSA certify different fields they used to use a arial photo and a grid overlay that is reasonabally accurate, +- . to a tenth of an acre The last time it was on a computer said to be nuts on. Used a graphic program of some sort. If you had a scale drawing/photo and a overlay grid you would get very close. How accurate do you have to be?
ED
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--Not enough info to give an answer. Now if you could meter flow and add an inch of depth to the water you'd have the info you need..
--
"Steamboat Ed" Haas : Proud to be the
Hacking the Trailing Edge! : family crackpot!
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| --Not enough info to give an answer. Now if you could meter flow and | add an inch of depth to the water you'd have the info you need.. | | -- | "Steamboat Ed" Haas : Proud to be the | Hacking the Trailing Edge! : family crackpot! | www.nmpproducts.com | ---Decks a-wash in a sea of words---
If the depth of the pool is pretty much constant you can fill the pool with water and find out how much volume it holds with an accurate water meter. With that information you can use the formula: V = Area X Height then, Area = Volume / Height
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On Thu, 24 Aug 2006 19:48:46 -0700, the renowned "Steve B"

If you have a reasonably accurate scale drawing or aerial photograph (Google Earth?) of the pool, you could trace it onto graph paper and count the squares (round squares of less than half down, and more than half up), then scale by a single measureable dimension to get the total area in real-world units.      A quick google seems to indicate that most kidney-shaped pools have about a 2:1 ratio of lengths, so checking a generic pool drawing might be fairly close. Then you could scale it to other sizes by the square of the perimeter. Eg. if you have the area of a pool with a perimeter of 100', and you need to know the area of a 132' perimeter pool it would have area of: X * (132/100)^2 = 1.74 * X , where X is the area of the 100' perimeter pool.
Best regards, Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
snipped-for-privacy@interlog.com Info for manufacturers: http://www.trexon.com
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Steve B wrote:

Cut a bubble-pack, pool cover to fit inside the edge. Cut 1 sq-ft of the same material. Weigh them both. Divide the big one by the little one.
This sounds like an "Angels on a Pin" question.
--
Gary A. Gorgen | "From ideas to PRODUCTS"
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Get yourself a math book and look up Simpson's #1 Rule or Simpson's #2 Rule.
Bob Swinney

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You can't do it mathematically from just the perimeter. The formula for area used by pool companies is to add the width of the narrow and wide ends together. Multiply by the overall length and then by .45.
For example Narrow end = 12' wide, Wide end = 18' total = 30' Length @' ((12+18)* 40)/.45 = 540 sq.ft (approximately)
--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
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Steve B wrote:

See if you can spot your pool on a Google satellite map, clip the pool image, enlarge it, and print it.
Then cut out the pool shape, weigh it on a lab balance and calculate the area by comparing the weight of the "pool shape" to the weight of a known rectangle of the same paper you printed the image on. (Ignore the addrd weight of the ink.)<G>
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
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On Fri, 25 Aug 2006 07:59:03 -0700, "Steve B"
The best suggestion has been to divide the pool into 5' or 2' etc segments and measure the width across the end of each segment (Roy I think). Each segment is a rectangle x' wide and poolwidth' long. If you need more accuracy, either use short segments or triangles at the ends on the curvy bits.

Yep. And if the kids with buckets lower the pool by exactly 1/2" you can find that area, because you know the depth of the sample.
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Steve B wrote:

This question brings up the image oaf a hatchet planimeter, which gets my vote as the coolest, and most elegantly simple device I've ever seen to do a complex job.
It is bent piece of wire, that is traced over the outline, and yields the area.
http://www.antiquark.com/2004/12/prytz-hatchet-planimeter.html
Pete
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On 27 Aug 2006 14:42:33 -0700, snipped-for-privacy@centurytel.net wrote:

Wow. Never heard of that. Very interesting and non-intuitive (at least to me). Took me a while to understand what they were doing. Looks like an interesting project for a metal worker.
Building and setting one up to measure a swimming pool might be a little impractical, though.
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xray wrote:

Yeah, that is ONE Cool invention! Not practical to use on a 1:1 layout of a pool, but for a smaller picture, it will work OK. And, the longer the arm, the more accurate it is according to the website. My vote for the most complex task performed by the simplest machine possible. Pete