Water, water (hopefully not everywhere)

Anything goes, but keep it seemly...

Water, water (hopefully not everywhere)

I'm in the process of filling a swimming pool and am trying to figure out how many gallons it will hold. I know how to find the volume of the cylinder but don't know how to convert that to gallons. Anybody know how many gallons in a cubic foot or something similar?

Tracy
TKiel

Posts: 209
Joined: 05 January 2006

Measure pool in centimetres and convert gallons to litres.
underquark

Posts: 299
Joined: 06 September 2005

Or try this : Conversion Calculators

Unbelievably, I found this on Google.

Luna
*the cubic metres are further down the list than cubic centimetres*
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

Thanks luna, that's a cool link.

28' diameter pool
4' sidewalls

volume of pool = 2461.76cuft

gallons(US) = 18,415.19568
gallons(British) = 15333.810688000001
liters = 69707.68851200001

Tracy
TKiel

Posts: 209
Joined: 05 January 2006

Thanks very much !

I do hope that you don't have a hosepipe ban, or is that just a British invention?

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

Is this a solid pool or one of them soft-walled, collapsible ones? If the latter then you might need to allow for equatorial bulge. Your cylinder then becomes part of an ovoid structure allowing for a bit more bulge towards the bottom of the walls than at the top (otherwise it woud be part of a sphere).
underquark

Posts: 299
Joined: 06 September 2005

But if it's an inflatable pool, does that make a difference?

Anyway ..............

Apparently, if it does have equatorial buldge then that would make it an oblate spheroid - according to Wikidpeida, in which case the formula for an oblate spheroid is :

* 4/3 x pi x a^2 x b where

* a is the semi-major axis length
* b is the semi-minor axis length

Which would give me a headache so I'd plump for Volume of an Oblate Spheroid

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

It has solid sides, so no need to allow for the equatorial bulge.

lunababy_moonchild wrote:I do hope that you don't have a hosepipe ban

Not sure what that is.

Tracy
TKiel

Posts: 209
Joined: 05 January 2006

A hosepipe ban is where the council - don't know what the American equivalent would be but it's the local authority that is responsible for making sure that the street lights are on and the rubbish is collected etc - ban householders (and taxpayers) from using hoses to water the garden/wash the car and, I assume, from filling a pool, paddling or otherwise.

Some parts of England have them in place just now (it varies from area to area) and it's reckoned that that may lead to standpipes in the street some time this summer. We don't and nor, to my knowledge have we ever had to, ban hosepipes here in Scotland (too much rain for that! Never thought that I'd be grateful for the rain)

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

Re: Water, water (hopefully not everywhere)

TKiel wrote:"... Anybody know how many gallons in a cubic foot or something similar?"

This is taking me back many years but it was six and one-quarter (6 1/4) gallons in a cubic foot of water.

Cec
Cec

Posts: 1039
Joined: 16 June 2005

Where I live we average between 6 and 7 inches of rain per year. I've lived here for 31 years and we have never had a ban on using water. Occasionally when the reservoirs get low, they suggest we cut back on our water usage, but the rains always come and flood us out before the next drought. My swimming pool is now 89 degrees F (34C). All our family on our east coast have bans periodically since water storage is a problem there. We have 5 lakes holding water.

Thanks for the "hosepipe" explanation. I'd never heard of that term.
Hud

Posts: 570
Joined: 29 October 2005

Cec, that must be "Imperial Gallons"

This is taking me back many years but it was six and one-quarter (6 1/4) gallons in a cubic foot of water.

I'm using rough calculations of a cubic foot of water weighing 62 pounds and a US gallon, 8 pounds. Sorry to be such a smar tass.
Hud

Posts: 570
Joined: 29 October 2005

Some folks say that everything in America is bigger. So how come you have eight-pound gallons and ours weigh ten? And how come I need to buy bigger shoes if I get them in the US? Mind you, since we're all European now in the UK, I take a whopping big 45.

Incidentally, doesn't an oblate spheroid strictly imply a greater equatorial radius than that towards the poles but - since it is a rotational extrusion of an ellipse spun about its minor axis - that the radius would be equal at the "top" and "bottom" of said object. Since gravity would be involved in a collapsible swiiming-pool (and might, for that fact, come into play even in a concrete-walled one, albeit to a much, much lesser degree) then this would be more like a cross-section of an egg in the traditional little-endian configuration.
underquark

Posts: 299
Joined: 06 September 2005

Water, water (hopefully not everywhere)

Hud wrote:Cec, that must be "Imperial Gallons"

Oops! you're right Hud ...I forgot about that. Hope Tracy hasn't set a timer on my calculations

Cec
Cec

Posts: 1039
Joined: 16 June 2005

underquark wrote:Incidentally, doesn't an oblate spheroid strictly imply a greater equatorial radius than that towards the poles but - since it is a rotational extrusion of an ellipse spun about its minor axis - that the radius would be equal at the "top" and "bottom" of said object. Since gravity would be involved in a collapsible swiiming-pool (and might, for that fact, come into play even in a concrete-walled one, albeit to a much, much lesser degree) then this would be more like a cross-section of an egg in the traditional little-endian configuration.

Yes it does. I did think of that initially, but since that was the only formula I could find that came close - and I thought that it was a theoretical exercise anyway - I decided to post it, just for the fun of it.

In your example what would the formula be, as a matter of interest?

I thought that you could just use the 'bottom end' as the minor axis and achieve the same result. Or you could use : Egg Volume (The PDF version gives the pictures, which I found useful, but I couldn't figure out a way of posting the link). Which seems to me an overly complicated way of doing it. The only other way of measuring the volume of an egg is to measure the water it displaces, which clearly in this case, is not appropriate.

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

Next