RECox286 wrote:True story: (myths...)
When one of my customers was having their pool cleaned, and refurbished, the contractor drained the tub completely, but then he opened the bilge plug, and threaded a 4' length of pipe into the open hole. His reasoning was: even with the tub drained out, by opening the plug, and inserting a pipe, all the pressure of ground water trying to push the pool out of the ground, would be eliminated, and the pool would be "safe" (meaning that the pool tub would not be bouyant). And he actually believed it.
Fortunately, the concrete was heavy enough, and the ground water was deep enough that the pool did not Surface, Surface, Surface !
Ergo: if you are in a floating boat, and you happen to drill a hole in the floor, and just so happen to have a length of pipe to stick in the hole, all the pressure will be relieved, and the boat will immediately sink.
Think about it...
Back in school we built boats made out of concrete. The weight of concrete alone is not enough to resist Archimedes principal.
You are correct that the low height of ground water is the reason why the pool didn't float.
It is totally absurd to believe that a pipe installed as stated would do anything other than let ground water in if it penetrated the water stratum.
If you put a pipe in the bottom of a boat and it extended above the surrounding water level the pipe would just fill the pipe to an equilibrium height.
Moral when boating pack a sufficient length of pipe to stay afloat.