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2. The Instrument Fuselage and Arms 



The fuselage section of the instrument is ten inches in 

 diameter and forty inches in length, (Figure III-3) . It secures a 

 circular plate with five pressure-sensing "isolation" diaphragms and 

 a water-tight cylinder that contains the pressure transducers. Both 

 ends of the fuselage are covered by plexiglass plates to prevent 

 large marine animals from entering the inside of the instrument. The 

 top plate contains a number of 5/8 inch holes to allow the fuselage 

 to flood and ensure that the pressure-sensing diaphragms therein are 

 communicating with the outside. The bottom plate has a one inch wide 

 slit cut across its radius to allow the cable entry to the fuselage 

 and water-tight cylinder. Both plates are secured to the cylinder by 

 titanium bolts attached to PVC blocks on the inside of the fuselage. 

 The blocks are made fast to the fuselage by adhesives and nylon 

 screws. 



Each of the four arms penetrate the fuselage and are held 

 therein by a PVC "spider." A spider is a common plumbing junction 

 which connects four pieces of tubing at ninety degree angles to one 

 another. Four bolts are tapped through the spider to secure the 

 arms. In this way, any or all of the arms can be disconnected for 

 greater ease in transportation, or potentially, a change in arm 

 orientation. 



