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54 Cards in this Set
- Front
- Back
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what is the most important tasks of a QM whenever your ship enters or leaves port.
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calculating how much water will be available along your route of transit.
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how are depth soundings referenced in all navigational charts
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in mean low water
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tidal day
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the rise and fall twice daily of tides.
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tidal cycle
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the period of one high and one low tide
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maximum height of the water resulting from the rising tide
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high tide or high water (HW)
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minimum height of water resulting from the outgoing tide
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low tide or low water (LW)
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duration of rise and fall of a tide
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period of time measured in hours and minutes that it takes the tide to go from low water to high water
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distance between HW and LW
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range of tide
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stand of a tide
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a brief period where no rise or fall occurs. when tide reaches out maximum or minimum level
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mean high water (MHW)
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the average height of all high-tide water levels, measured over a 19 year period
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mean low tide (MLW)
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the average height of all low-tide levels, observed over a 19 year period
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what is mean lower low water (MLW)
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the average of the lower of the low water levels, observed over 19 years
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what is the reference plane currently used on almost all charts covering U.S. waters as the basis of measurement of chart depths and height of tide
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mean lower low water (MLW)
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spring tide
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when solar and lunar influences are in line with the earth with higher and lower tides than average
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when do spring tides occur
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when influences of the sun and moon act together
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when do neap tides occur
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when the direction of the sun and moon are 90 deg apart, and the gravitational effect of the sun Conner acts that of the moon enough that both high and low tides are less than normal
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semidiurnal tides
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where two high and two low tides occur each tidal day and they occur at fairly regular intervals
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where do semidiurnal tides occur
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on the Atlantic coast
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diurnal tides
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where there is only one high and one low tide each day
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in the United States, where are diurnal tides found
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along the northern shore of the gold of Mexico
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what is the characteristic of the tidal pattern in mixed tides
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wide variations in hights of successive high and low waters
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where are mixed tides found in the United States
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along the Pacific coast, Alaska, and Hawaii
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what is charted depth
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vertical distance from the low - water reference plane to the ocean bottom
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what is charted height
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vertical distance above the water measured from the high - water reference plane
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mean range of tide
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vertical distance between the high water and low water reference plane used. represents the average range of tides at a given area.
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who publishes tide tables annually
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National Oceanic and Atmospheric Administration (NOAA)
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how many volumes are used for the NOAA tide tables
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4
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what is contained in table 1 of the NOAA tide tables
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the predicted times and heights of high and low waters for each day odd the year at a number of places called reference stations
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what is contained in table 2 of the NOAA tide tables
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tidal difference information for heights and times at a number of places called subordinate stations
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what is contained in table 3 of the NOAA tide tables
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information used for finding the approximate height of the tide at any time between high and low water
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what is contained in table 4 of the NOAA tide tables
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a sunrise - sunset tablet listing LMT of the sun's upper limb for every 5th day odd the year
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what is contained in table 5 of the NOAA tide tables
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an adjustment to convert the LMT found in table 4 to zone or standard time
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what is contained in table 6 of the NOAA tide tables
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the zone time for moonrise and moonset for each day odd the year at certain places
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what is contained in table 7 of the NOAA tide tables
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a conversion of feet ton meters table
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when can the graphical method odd determining tides be very useful
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when the height of tide is required for a number of tides on a certain day
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the advantage of having tides displayed on a graph for the entire day if you are servicing navigational aids in one particular area
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do to the tide, in fact, many mariners speak of "the tide" when they actually have the flow of the tidal current in mind.
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what are currents
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the horizontal movement of water, may be classified as either tidal or nontidal.
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what is flood current
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when the horizontal movement of water is toward shoe or up a tidal river or estuary
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what is ebb current
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when the horizontal movement is away from shore or down a tidal river or estuary
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what is slack water
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the period is time where there is little or no current is called the minimum before flood or ebb.
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what is the term for the direction odd current and Is expressed in the direction TOWARD which the current flows
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set
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what is the term for the velocity of the current and Is sometimes referred to as drift
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speed of current
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what is rotary current
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one that flows continually with the direction of flow changing through all points of the compass during tidal period.
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what is the effect on the ship by tide rips caused by swift tidal current flowering over an irregular bottom
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they often set up rips and eddies that are nearly always deceptive in appearance and will sometimes change a ships direction by as much as 30 deg.
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where's are tidal current most pronounced
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in the entrances to large tidal basins have restricted openings to the sea.
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what is a major characteristic of a tide rip
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the coloring of the water
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how often are Tidal Current Tables issued in 2 volumes
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annually
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what is Table 1 odd the Tidal Current Tables
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Daily Current Predictions
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what is Table 2 of the Tidal Current Tables
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Current Differences and Other Constants and Rotary Current
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what is Table 3 of the Tidal Current Tables
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Speed of Current at Any Time
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what Ida Table 4 of the Tidal Current Tables
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Duration of Slack
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What is Table 5 of the Tidal Current Tables
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it lists data for a number odd offshore stations for the direction and average speed of rotary tidal current for each hour of the tidal cycle
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the graphing of current velocity information is generally the same as what data.
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graphing tide data
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what time is used to graph tidal currents
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the time between slack water and maximum current
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