Abstract: A low voltage power system for a towed active array sonar is provided. The ow voltage power system includes a shipside power supply driving a step-up transformer which is connected to the tow cable transmission line. The transmission line is connected to a second step-up transformer which provides the signal voltage to the active transducer. The transducer signal voltage is also used to drive a rectifier and DC power supply which provides DC bias voltage to the transducer. The DC voltage is isolated from the tow cable by a blocking capacitor.

Abstract: The space between the inner wall of a petroleum or hydrocarbon tank or similar storage tank and a floating roof therein is sealed by both a primary seal and a secondary seal. The secondary seal, which has no elastomeric parts subject to rapid deterioration, includes a flexible vapor barrier fabric having a first edge coupled to the floating roof and an opposite second edge. The secondary seal further includes a plurality of plates disposed above the vapor barrier fabric and having lower ends coupled to the floating roof and opposite upper ends coupled to a metal shoe disposed against the inner tank wall and having the second edge of the vapor barrier fabric coupled thereto. The length of each metal plate between upper and lower edges thereof is adjustable by virtue of the plate being comprised of overlapping upper and lower plates joined by bolts in elongated apertures therein.