Abstract: A method and apparatus for conducting a survey to determine the location and elevation of a buried pipeline located in a shallow water environment. The method includes determining whether submerged obstacles are located between the ends of that portion of the line being measured and measuring the depth of the line by taking magnetic sounding of the buried line at spaced intervals by crossing the line at longitudinally spaced points with the magnetic survey apparatus. The apparatus includes a towed sled for carrying the magnetic sensing device.

Abstract: A plunger tool is provided having a nose assembly to slow the descent of the tool into the well, a valve assembly, and a piston cylinder assembly. When the tool is dropped into the well, the gas and liquids in the well flow through restrictions in the nose assembly, thereby braking the fall. The fluid flows along a fingered collet which retains an angled valve. The fluid flows around the opened valve and out of the upper end of the plunger lift tool. The valve is connected to the piston which is exposed to ambient pressure on one side and a predetermined pressure on the other. Thus, the piston is set to close the valve at a predetermined pressure. As the pressure builds up, the piston moves the valve so that a lower portion of the valve is gripped by a detent mechanism, in this case collet fingers. When adequate pressure is built up to unsnap the valve, the piston forces the valve out of the detenting collet fingers and into its seat. Formation pressure from below the seal increases the sealing force.

Abstract: A cage to retain an undersea vehicle therein and tether reel-in and play-out mechanism is provided. The cage includes a latch for retaining the vehicle in a "garage" portion. A tether drive assembly reels in and out the tether line through a bale which cooperates with a narrow, annular drum to retain the tether line in an annular, cylindrical coil having a width of a single strand of line. The bail, with or without cooperation from additional means, winds and unwinds the tether in the drum.

Abstract: The data selection circuit includes a multiplexer circuit which receives a plurality of inputs and individually connects each of the inputs to an output line. The multiplexer is sequenced by signals from a timing circuit which causes inputs having a higher signal level to be connected to the multiplexer output for a greater length of time. The data selection circuit is particularly suitable for enhancing the image on a CRT of a continuous tone frequency modulated sonar system.