Navi 3
Understanding Tides and Tidal Measurements
Test your knowledge about tides and tidal measurements with this comprehensive quiz! Perfect for mariners, students, and anyone interested in understanding the complex world of tides.
Key Features:
- 25 Multiple Choice Questions
- Covers various types of tides and their measurements
- Score as you go and learn along the way!
96. What does the tidal current do?
It flows horizontally.
It rises and falls vertically.
It remains stationary.
None of above
97. What does the tide do?
It flows horizontally.
It rises and falls vertically.
It remains stationary.
None of above
98. What is high tide?
The minimum level of the tide
The period during which there is no apparent change of level
The maximum height of the tide
The difference in height between consecutive high and low waters
99. What is low tide?
The maximum height of the tide
The period during which there is no apparent change of level
The difference in height between consecutive high and low waters
The minimum level of the tide
100. What does the high water datum mean to the mariner?
It gives a margin of error when passing under obstructions.
It tells the mariner the exact height of the obstruction.
It indicates the height of low tide.
It indicates the height of the highest tide of the day.
101. What are the three types of tides?
High, low, and mixed
Semidiurnal, diurnal, and mixed
Spring, neap, and mixed
North, South, and mixed
102. In which type of tide are there two high and two low waters each day?
Diurnal
Mixed
Semidiurnal
None of the above
103. How many high and low waters occur each tidal day in a diurnal tide?
Two high and two low
Only one high
Only one low
One high and one low
104. Which type of tide is characterized by a large inequality in high water heights, low water heights, or both?
Mixed
Diurnal
Semidiurnal
None of the above
105. Can the tide become diurnal in a mixed tide?
No
Yes
Only in semidiurnal tide
Only in diurnal tide
106. What causes spring tides?
First and third quarters
Solar tractive forces only
New and full moon
Lunar tractive forces only
107. When do neap tides occur?
New and full moon
Solar tractive forces only
Lunar tractive forces only
First and third quarters
108. What is the range of tide during spring tides?
Greater than average
Less than average
Equal to average
No change in tide range
109. Why is the range of tide less during neap tides?
Solar tractive forces only
Solar and lunar tractive forces act at right angles
Lunar tractive forces only
No change in tide range
110. What is a tidal datum?
The average height of high tides
The average height of low tides
A level from which tides are measured
The depth of water available at any time
111. What is the most important level of reference to the mariner?
Mean sea level
Sounding datum
Low water springs
Tropic lower low water
112. What is the purpose of recording the tide during a hydrographic survey?
To determine the average height of low waters
To predict the heights above and below mean sea level
To reduce soundings taken at all stages of the tide to a common sounding datum
To determine the depth of water available at any time
113. What do soundings on charts show?
Heights above a selected low water datum
Depths below mean sea level
Heights above mean sea level
Depths below a selected low water datum
114. By international agreement, what should the level used as chart datum be?
Low enough so that low waters do not fall very far below it
High enough so that high waters do not rise very far above it
The average height of all low waters at a given place
The average level of the low waters that occur at the times of spring tides
115. What is mean low water (MLW)?
The average level of the low waters that occur at the times of spring tides
The average height of all low waters at a given place
The average height of the lower low waters of each tidal day
The average height of the lower of the two low waters on the days of spring tides
116. What is tropic lower low water (TcLLW)?
The average height of all low waters at a given place
The average level of the low waters that occur at the times of spring tides
The average height of the lower low waters (or of the single daily low waters if the tide becomes diurnal) that occur when the moon is near maximum declination and the diurnal effect is most pronounced
A low water datum that includes the spring effect of the semi-diurnal portion of the tide and the tropic effect of the diurnal portion
117. What is Indian spring low water (ISLW)?
A low water datum that includes the spring effect of the semi-diurnal portion of the tide and the tropic effect of the diurnal portion
The average height of the lower low waters (or of the single daily low waters if the tide becomes diurnal) that occur when the moon is near maximum declination and the diurnal effect is most pronounced
The average height of all low waters at a given place
The average level of the lower of the two low waters on the days of spring tides
118. What is lowest normal low water?
An extremely low datum that conforms generally to the lowest tide observed, or even somewhat lower
A datum that approximates the average height of monthly lowest low waters, discarding any tides disturbed by storms
The average height of the lower low waters of each tidal day
The average level of the low waters that occur at the times of spring tides
119. What are datums used in a limited area and primarily for river and harbor engineering purposes called?
Boston Harbor Low Water Datum
Columbia River Lower Low Water Datum
Low water datum, lower low water datum, etc.
Lowest normal low water
120. What is the high water datum widely used?
Mean high water springs (MHWS)
Mean higher high water (MHHW)
Tropic higher high water (TcHHW)
Mean high water (MHW)
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