Aluminum Sea Marker Mk V (Sevice)

Description: The sea-marker body has an inner case of sheet metal, the lower end of which is pressed on to a heavy, apertured head. The aperture in the head is sealed by a paper disc and is traversed by a pin. A circular retaining piece is secured to the upper end of the inner case. Inside the inner case is a fabric bag containing aluminum powder, each end of the bag being tied with thread to close it. The thread at the lower end of the fabric bag is passed around a pin, to hold the bag in contact with the head. An outer case slides over the inner case. At its upper end the outer case is closed by two mill-board discs, and inside its lower end a circular retaining piece is secured to provide a stop to prevent its being withdrawn completely from the inner case. A cutter is provided immediately below the millborad discs. The cutter is a ring secured inside the outer case and cut across in four places at about 45 degrees. The cut ends are bent up at right angles to form four sharp projections within the outer case.

Functioning: The head is the heaviest part of the marker and consequently will strike the water first when dropped. Impact with the surface of the water breaks the paper disc sealing the aperture in the head. Water enters this aperture and carries the fabric bag rearwards from the head, breaking the thread which anchors it to the pin and also ejecting the millboard discs sealing the aperture at the tail end of the outer case. As the bag passes through this aperture, it strikes the sharp projecting parts of the cutter, which slit it, releasing its contents. As a result a slick of aluminum powder is formed on the surface of the sea.

Remarks: This marker contains no explosive.

Figure 101 - Aluminum Sea Marker Mk V