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David, I wonder what the acoustic properties of syntactic foam or lead is? I know some military subs have over a inch of rubber type coating on the exterior of there hull for a number of reasons. Including I believe absorbing active sonar. Perhaps for a channeling device you could use a large capped at one end FRP, PVC or ABS plastic tube coated with a thick layer of rubber, or Rhino type coating on the exterior of the tube, would absorb noise on the outside of the tube, but allow in noise coming from the direction the tube is pointed. My 2 pennies worth. My grandpa always told me I could build just about any thing if I had two pennies to rub together. I've just about rubbed those pennies to half there original thickness. ;} Regards, Szybowski From: dbartsch2236@hotmail.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] DSV 3 Turtle, Styrofoam Shot Glass Date: Wed, 8 Jul 2009 01:39:00 -0400 Brent, The reason for my quest for finding or using foam is this: I need a substance that has a drastic difference in medium than that of water (salt or otherwise) the reason being I need this barrier to reflect sound rather than absorb it. The piezo elements we use are actually omni-dirrectional and I need this barrier to channel the sound from a set direction into this element. If this barrier is not seen by sound, (as cork was suggested) but is simply passed thru it, this will be of little use to me. sound will be heard by hydrophones on the opposite side of a circular array farthest from the sound source. From the earlier discussion, I have chosen plastic juice cups at least for initial array testing. (Other channeling devices made from differing materials could be used in later sessions.) This I will further explain as this testing array becomes presentable and should should also generate great discussions. I should point out again that I am not all knowing about this field of passive sonar or hydrophones and welcome any suggestions or things discovered thru testing and experimentation. By combining the sum of all of our know how, we can derive at better sound reception for our use aboard these submarines. This is a road to learning that is best when shared with all. David Bartsch From: brenthartwig@hotmail.com To: personal_submersibles@psubs.org Subject: [PSUBS-MAILIST] DSV 3 Turtle, Styrofoam Shot Glass Date: Tue, 7 Jul 2009 01:07:55 -0700 Hi David and Vance, It's interesting that just before you guys started to talk about the styrofoam going deep, I was sizing and uploading pictures I very recently took when I got to spend a fun day with a friend of mine by the name of Joe Hurst. The pictures I took were of a signed styrofoam cup for Joe that went down 10,000 fsw with the DSV 3 Turtle in 1987. Joe is a composites expert, and worked extensively on the Turtle and Sea Cliff DSV's. I've got a pile of interesting data from Joe for you guys. http://cid-5085d10eb6afe47c.skydrive.live.com/browse.aspx/Turtle%20DSV%203%20%20Pictures Regards, Szybowski To: personal_submersibles@psubs.org Subject: [PSUBS-MAILIST] Re: [PSUBS-MAILIST Date: Sat, 4 Jul 2009 10:34:45 -0400 From: vbra676539@aol.com One other thing to do is have everyone involved sign a cup, write info on the dive (location, depth, dive number, etc). The cup will squash, and the writing will squash at exactly the same rate. It will still be neat and legible after the dive and your passengers will have a neat little souvenier of their dive. It only works partially in shallow water, but after a couple of hundred feet, you get a shot glass for the bookshelf that will not reexpand or change. I've still got a few from memorable dives. The ABS certification dive on PC-8 in Norway for instance, plus my first time over a thousand feet, over two thousand and then at nearly five thousand (Pisces VI in Canada). Vance -----Original Message----- From: Juergen Guerrero Kommritz <groplias2@yahoo.com> To: personal_submersibles@psubs.org Sent: Sat, Jul 4, 2009 8:11 am Subject: Re: [PSUBS-MAILIST]
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