Abstract: A system of three or more hydrophone arrays are utilized to measure underwater areal sound intensity. The hydrophone arrays bound at least one plane through which an areal sound intensity measurement is desired. Each hydrophone array comprises three orthogonal pairs of hydrophones with coincident acoustic centers. The output of each hydrophone in the system is simultaneously sampled and the outputs processed to obtain a vectorial sound intensity representation at each of the hydrophone arrays from which a representation of the areal sound intensity across the noted plane may be derived.

Abstract: A positionable transducer array on a stationary platform proximate a layered site on the seabed coherently insonifies locations at the site with a signal having a selected power, resultant center frequency, beamwidth, bandwidth, shape and incident angle. A positionable receiver array on the platform captures the return signals. Sub-surface acoustical properties of the location are then predicted from the return signals and a calculation of the speed of sound in water at the site. Subsequent locations at the site are then interrogated and an interpolation is made of acoustical properties between locations to develop a model of the acoustical properties at the site.

Abstract: A gang of adjacent hooks of a longline are located in a side-by-side spaced relationship. The gang of hooks are retained in a fixed position with respect to one another while bait is impaled on the hooks. The bait is cut into individual bait portions for each of the hooks.

Abstract: A fish hook storage magazine for storing the hooks of a longline during baiting and longline shooting is formed with a slipway for slidably supporting the hooks. The hooks are formed with a spacer which is mounted on the shank of the hook. The slipway and spacer have complementary interlocking profiles which permit lengthwise movement of the spacer with respect to the slipway while preventing removal of the hooks in a direction perpendicular to the slipway and rotation of the hooks about their shank. A bait applying mechanism is also provided which includes a bait support for supporting bait during hooking and a guide for guiding the bait support relative to the hook support to permit relative movement therebetween along a baiting path whereby the bait supported on the bait support is supplied to each hook of a gang of hooks mounted in the magazine. A bait cutting mechanism is also provided for cutting the bait after it is applied to the hooks.

Abstract: The submersible drydock system of the present invention is one in which the buoyancy of the docking platform is altered to effect raising and lowering thereof. The submersible dock comprises a submersible platform having a buoyancy chamber formed therein. Foundations are located below the platform and a parallelogram linkage system interconnects the platform and the foundation. The parallelogram linkage system is operable to retain the platform in the generally horizontal plane in all positions during raising and lowering of the platform. A buoyancy control system is provided which communicates with the buoyancy chamber to vary the amount of air within the chamber to effect raising and lowering of the platform relative to the foundation.