1) I am operating astern propulsion. 2) Sound signal; I am operating astern propulsion. 3) S flag + two numerals Speed in Knots.

Related Terms


A term pertaining to sound, or the science of sound.


The normal sound in a room or other location.


Sound which reaches the point of interest by radiation through the air.


A current in a channel caused by a difference in the surface level at the two ends. Such a current may be expected in a strait connecting two bodies of water in which the tides differ in time or range. The current in the East River, N.Y., connecting Long Island Sound and New York Harbor, is an example.


A type of precipitation consisting of transparent or translucent pellets of ice, 5 millimeters or less in diameter. The pellets may be spherical, irregular, or (rarely) conical in shape. They usually bounce when hitting hard ground, and make a sound upon impact. Ice pellets includes two basically different types of precipitation, those which are known in the United States as SLEET and SMALL HAIL. Sleet is generally transparent, globular, solid grains of ice which have formed from the freezing of raindrops or the refreezing o


A depth finder that uses sound waves to determine the depth of water.


Said of a sound signal or radionavigation aid out of service due to a malfunction


The type of buoy with a large bell and hanging hammers that sound by wave action.


A sound signal which uses electricity or compressed air to vibrate a disc diaphragm.


Any undesired sounds, usually of different frequencies, resulting in an objectionable or irritating sensation.

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