Hello David and Vance
the Styrofoam cups are allways a nice joke in deep sea expeditions, we put then in a bag attached to the epibenthic sledge or Box corer or Multicorer and let them go down to the bottom and when the device comes again on board with the sample we also have tyni cups and are allways a nice suvenir from the expedition. Other nice joke in holydays like easter is to put some boiled eggs in a bag and send them down. If they go to 4000 m deept the presure push saltwater inside the egg so when you get it on board again with the sample you have a salted egg. :-)). Crazy things people do after some weeks on open ocean. Well part of the scientific study of effect of pressure.
Best wishes
Jürgen
--- vbra676539@aol.com <vbra676539@aol.com> schrieb am Sa, 4.7.2009:
Von: vbra676539@aol.com <vbra676539@aol.com>
Betreff: Re: [PSUBS-MAILIST]
An: personal_submersibles@psubs.org
Datum: Samstag, 4. Juli 2009, 13:13
David,
Styrofoam is a closed cell styrene foam and will compress almost immediately. Cups will go from coffee size to shot glass size at just a couple of hundred feet. Wig stands (the head you spoke of) will be slower on the inside at shallow depths, but will distort almost immediately, just like the cups. The issue is not really about crushing the air out--it is the physical collapse of the foam chambers (the bubbles). They do on come back, once crushed.
Vance
-----Original Message-----
From: David Bartsch <dbartsch2236@hotmail.com>
To: personal_submersibles@psubs.org
Sent: Sat, Jul 4, 2009 5:49 am
Subject: [PSUBS-MAILIST]
I remember years ago seeing an article in a National Geographic showing Alvin in which a styrofoam head was shown after the submarine had come back up from very deep. This head was stored in an external retrieval basket and was thus subjected to the pressure of this deep dive. It was shown compared to what the head looked like prior to the dive and was quite small having most of the air within it crushed out.
How much pressure or rather how deep must styrofoam go down to expel the air within it? If it were perhaps just cups and not thicker, would it go down to say 500 feet without
being crushed smaller?
Anyone have any idea? I was concidering using simple styrofoam as an inexpensive sonar baffling for reletively shallow operations. How far down should this be good for without changing shape upon returning topside?
David Bartsch
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