Abstract: A channel-shape sweep line retainer extends along the leading front edge of an elevating fin, with the open side of the retainer facing the trailing rear edge of the fin. Extending across the fin at the open side of the retainer is a bar mounted on the fin for movement toward and away from the retainer, but normally locked in its forward position by a pair of laterally spaced arms extending rearwardly away from the bar with their front ends engaging it. The rear ends of the arms are pivotally connected to the fin so that when arm-positioning spring means between the arms and connected to them are pulled rearwardly, the front ends of the arms will be swung inwardly toward each other out of engagement with the bar, whereupon the bar can be retracted to open the retainer for admission or release of a sweep line.

Abstract: A cable cutting member is adapted to be driven forward in a cable holder to cut a cable therein. For driving the cutting member, an explosive charge is detonated by a spring pressed firing pin slidably mounted in the holder behind the charge. A firing pin retractor slidably mounted in the cable holder behind the firing pin is detachably connected with the pin for retracting it a predetermined distance to compress the firing pin spring, the connection being such that when the pin has been retracted a given distance, it will be released automatically. A considerable distance behind the retractor there is a cylinder having a front end and a closed rear end and containing a piston spaced from both ends and mechanically connected with the firing pin retractor. The cylinder has an opening for water between its front end and the piston so that an increase in water pressure in the cylinder will move the piston rearwardly therein to pull the retractor far enough to release the firing pin.