Seiwa Starfish 2nd Edition - Manual (Page 73)

75 User Manual
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RTCM = Radio Technical Commission for Maritime Services
Data format created by the Radio Technical Commission Maritime to transmit
Differential GPS corrections.
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SCALE
Allows the display of Map Scale (magnitude of the reference scale expressed
in the actual unit of measure) and the current Map Datum.
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SNR = Signal to Noise Ratio
Ratio between the magnitude of a radio signal and the magnitude of the noise
(that is, the interferences). The SRN is expressed in decibels and it is associ-
ated to the GPS satellites signal quality.
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SOG = Speed Over Ground
Current velocity at which the vessel is travelling, relative to a ground location.
The SOG is normally provided by the GPS sensor.
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SPD = Speed Through Water
Speed of the vessel relative to the water.
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Spot Sounding
Depth of the water in a specific and charted position. It is represented on the
map by its own value expressed in the current depth unit.
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STR = Steering
Difference between COG and CTS. If COG is 25° and CTS is 30°, then STR is
5° Right.
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TD = Time Difference
Loran positions are determined by precise timing of the intervals between
reception of pulses transmitted by pairs of stations in the selected chain. Be-
tween any two stations a ship must be located somewhere along a line of
possible positions where the measured Time Difference, TD, between arrival
of pulses from those stations would be observed. The TD is measured from
the time of reception of the master station signal to the time of reception of
the slave station signal (see also Pair).
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Tide
Periodic rise and fall of the surface of oceans, bays, etc., due principally to the
gravitational interactions between the Moon and Earth.
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Tide Info
Calculates the tide heights for any past or future date and as a by-product of
this calculation will also display the Maximum and Minimum Tide height and
time for the day selected plus the times of Sunrise and Sunset. At some chart
levels, the chart plotter will display a new Tide Diamond Symbol for every Port
or tide point in the database covered by that particular DATA MEDIA.
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Tracks + Routes
Recommended and established routes for ships at sea, including traffic sepa-
ration schemes, deep water routes.
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TRN = Turning
Difference between COG and BRG. If COG is 80° and BRG is 75°, TRN is 5° Left.
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TTG = Time To Go
Estimated time needed to reach your destination, based on your current speed
and the distance to destination.
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TWD = True Wind Direction
Direction of the Wind relative to a fixed point on the earth.
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TWS = True Wind Speed
Velocity of the Wind relative to a fixed point on the earth.
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Underwater Objects
Objects like obstruction, wreck, cable…
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User Point
Object you place on the chart identified by its coordinates and displayed on