Tides Flashcards
What are tides caused by?
Gravitational effects of the Earth, moon and the sun
Which has a greater effect on tides? The moon or the sun?
The moon
How many high tides and how many low tides do most places have per day?
Most places have two high tides and two low tides per day
When do Spring Tides form?
When the sun and the moon are aligned
When do Neap tides form?
When the sun and the moon are not aligned
How long does it take for the moon to circle the Earth?
27.5 days
True or False?
Charts are drawn showing tide level at Chart Datum (CD)
True
What are depths measured from?
Chart Datum (CD)
What are clearance heights measured from?
Highest Astronomical Tides (HAT)
What does MHWS stand for?
Mean High Water Springs
What does MHWN stand for?
Mean High Water Neaps
What does MLWN stand for?
Mean Low Water Neaps
What does MLWS stand for?
Mean Low Water Springs
What are secondary ports?
Ports that don’t have very much commercial traffic
How often do Spring Tides occur?
Every two weeks
