ATSC 113 Sail Module A Exam Questions
with Correct Answers
Gravity waves - Answer-Larger winds create gravity waves, gravity acts as restoring
force, can be metres to km long
swell - Answer-- Waves that arrive from distant storms
- gravity waves originating from heavy winds capable of traveling long distances across
the ocean with little loss of energy
Great circle routes/paths - Answer-Shortest distance across earth's surface taken by
swell to travel
Rogue waves - Answer-Very large waves that form due to wave constructive
interference
destructive inference - Answer-If the crest of one wave passes through the trough of
another, they cancel out
- resulting wave is smaller and carries less energy
constructive interference - Answer-if the crest of one wave passes through with the
crest of another wave, they add up
- resulting wave is bigger, carries higher energy, but is temporary
Tsunamis - Answer-very long wavelength waves resulting from seismic events
Types of breaking waves - Answer-spilling, plunging, surging
Spilling breakers - Answer-- Waves traveling across a gently sloping bottom
- The wave breaks long and slow
Plunging breakers - Answer-- waves approach moderate to steep bottoms
- wave becomes steeper than a spilling breakers and the crest falls as a well-defined
curl
Surging breakers - Answer-- occur when long wave period, low amplitude waves
approach moderately steep shores
- wave doesn't spill or curl, it builds up and then slides rapidly up the beach with less
foam or spray than the other two breakers
tide - Answer-movement of the ocean surface up and down due to the gravitational pull
of the moon and sun
, New moon - Answer-sun and moon aligned
full moon - Answer-moon is on opposite side of the earth from the sun
quarter moon - Answer-sun and moon at right angles to each other
Spring tides - Answer-during full moon and new moon, the sun and moon's forces add
to each other, creating higher high tides and lower low tides than usual
Neap tides - Answer-during quarter moons, the sun and moon exert opposing forces on
the oceans and diminish each other's strength, creating weaker tides
- low tidal range
tidal range - Answer-The difference in levels of ocean water at high tide and low tide
flood currents - Answer-currents for incoming tide
ebb currents - Answer-currents for outgoing tide
currents - Answer-- horizontal movement of water
- knowing the timing and strength of the current tells you about how fast you can travel
to your destination and maybe what route you should take to get there
slack tide/current - Answer-moment of no current when the tide turns and changes
direction
- can expect to see two high slacks and two low slacks in a 24h period
high slack - Answer-when tide reaches its maximum height
low slack - Answer-when tide reaches its minimum height
peak current - Answer-at the midpoint between high and low tide
How to tell which way the current is going? - Answer-Look at buoy and see where the
wake forms behind it or look at boats at anchor (if they are not pointing into the wind,
there is likely a strong current controlling their position)
Tidal rapids - Answer-When fast-flowing tidal currents are forced to pass through narrow
channels, they can create dangerous tidal rapids with standing waves, large back
eddies and intimidating whirl pools
Environment & Climate Change Canada (ECCC) - Answer-marine forecast provided for
recreational cruising on Canadian coastlines
with Correct Answers
Gravity waves - Answer-Larger winds create gravity waves, gravity acts as restoring
force, can be metres to km long
swell - Answer-- Waves that arrive from distant storms
- gravity waves originating from heavy winds capable of traveling long distances across
the ocean with little loss of energy
Great circle routes/paths - Answer-Shortest distance across earth's surface taken by
swell to travel
Rogue waves - Answer-Very large waves that form due to wave constructive
interference
destructive inference - Answer-If the crest of one wave passes through the trough of
another, they cancel out
- resulting wave is smaller and carries less energy
constructive interference - Answer-if the crest of one wave passes through with the
crest of another wave, they add up
- resulting wave is bigger, carries higher energy, but is temporary
Tsunamis - Answer-very long wavelength waves resulting from seismic events
Types of breaking waves - Answer-spilling, plunging, surging
Spilling breakers - Answer-- Waves traveling across a gently sloping bottom
- The wave breaks long and slow
Plunging breakers - Answer-- waves approach moderate to steep bottoms
- wave becomes steeper than a spilling breakers and the crest falls as a well-defined
curl
Surging breakers - Answer-- occur when long wave period, low amplitude waves
approach moderately steep shores
- wave doesn't spill or curl, it builds up and then slides rapidly up the beach with less
foam or spray than the other two breakers
tide - Answer-movement of the ocean surface up and down due to the gravitational pull
of the moon and sun
, New moon - Answer-sun and moon aligned
full moon - Answer-moon is on opposite side of the earth from the sun
quarter moon - Answer-sun and moon at right angles to each other
Spring tides - Answer-during full moon and new moon, the sun and moon's forces add
to each other, creating higher high tides and lower low tides than usual
Neap tides - Answer-during quarter moons, the sun and moon exert opposing forces on
the oceans and diminish each other's strength, creating weaker tides
- low tidal range
tidal range - Answer-The difference in levels of ocean water at high tide and low tide
flood currents - Answer-currents for incoming tide
ebb currents - Answer-currents for outgoing tide
currents - Answer-- horizontal movement of water
- knowing the timing and strength of the current tells you about how fast you can travel
to your destination and maybe what route you should take to get there
slack tide/current - Answer-moment of no current when the tide turns and changes
direction
- can expect to see two high slacks and two low slacks in a 24h period
high slack - Answer-when tide reaches its maximum height
low slack - Answer-when tide reaches its minimum height
peak current - Answer-at the midpoint between high and low tide
How to tell which way the current is going? - Answer-Look at buoy and see where the
wake forms behind it or look at boats at anchor (if they are not pointing into the wind,
there is likely a strong current controlling their position)
Tidal rapids - Answer-When fast-flowing tidal currents are forced to pass through narrow
channels, they can create dangerous tidal rapids with standing waves, large back
eddies and intimidating whirl pools
Environment & Climate Change Canada (ECCC) - Answer-marine forecast provided for
recreational cruising on Canadian coastlines
