Ocean Current Systems

Learning Outcome:

Interpret the Ocean Current(s) and its

effect(s) on a predetermined route using
various Nautical Charts and Publications
Ocean currents are continuous movements
of water in the ocean that follow set paths.
They can be at the water's surface or go to
the deep sea.
 VIDEO:
Ocean Current
 Types of Ocean Currents:

Surface currents: Driven by wind, Coriolis

effect.

Deep currents: Driven by density

differences (temperature, salinity).

Tidal currents: Caused by gravitational pull

of the moon and sun.
SURFACE CURRENT

 Surface water circulation refers to the

movement of the upper layers of the ocean,
typically driven by wind, and the Earth's
rotation (Coriolis effect).

 This circulation plays a vital role in shaping

the global climate, marine ecosystems, and
navigation routes.
Deep Ocean Currents

 Deep ocean currents, also known as

thermohaline circulation, are driven by
differences in water density caused by
variations in temperature (thermo) and salinity
(haline).

 These currents form a global "conveyor belt"

that transports water and heat between the
surface and deep ocean layers, playing a critical
role in regulating Earth's climate.
 VIDEO:
Surface and Deep Ocean
Current
 Factors Influencing Ocean Currents

Wind: Primary driver of surface currents.

Coriolis Effect: Deflection of moving objects due

to Earth's rotation.

Temperature and Salinity: Influence water

density, driving deep currents.

Landmasses and Coastlines: Shape and direct

current flow.
 Primary Driver of Surface Currents:

Wind: The primary driver of surface currents,

wind exerts force on the ocean's surface,
transferring energy to generate currents.
Trade winds and westerlies play significant roles
in driving major current systems across the globe.
 Role of Coriolis Effect:

The Earth's rotation deflects currents, causing

clockwise circulation in the Northern
Hemisphere and counterclockwise circulation in
the Southern Hemisphere.
Temperature:
Cold water is denser than warm water.
As surface water cools, it becomes denser and sinks.
This sinking water initiates the movement of deep
ocean currents.
Salinity:
Saltier water is denser than less salty water.
When water evaporates, salt is left behind, increasing
the salinity and density of the remaining water.
In some regions, such as the Arctic and Antarctic, the
formation of sea ice also increases the salinity of the
surrounding water, making it denser.
 Landmasses and Coastlines:
Upwelling and Downwelling:

Coastlines can cause upwelling, where deep, cold

water is brought to the surface.
In areas where winds blow parallel to the coast,
surface water is pushed offshore, allowing deeper,
colder water to rise.
Conversely, downwelling occurs when surface
water is pushed towards the coast and sinks.
WIND IS COMING FROM NORTH
WIND IS COMING FROM SOUTH
 Identify Ocean Currents Along the Route

Major Ocean Currents: Identify large-scale

currents (e.g., Gulf Stream, Kuroshio Current) that
may affect the route.

Tidal Currents: In coastal areas, tidal currents can

significantly impact navigation. Check tidal stream
atlases for timing and strength.

Local Currents: Near harbors, straits, or narrow

passages, local currents may be strong and variable.
Major Ocean Currents and Their Effects
on Navigation

Ocean currents are large-scale water movements

driven by wind, temperature, salinity, and Earth's
rotation. They significantly impact maritime
navigation by influencing vessel speed, fuel
consumption, and safety. Below are the major
ocean currents categorized by ocean basin:
Atlantic Ocean Currents
Gulf Stream (Warm, Northward)
Location: Western North Atlantic, from Florida
to the North Atlantic
Effect: Speeds up vessels heading north but slows
southbound traffic
Canary Current (Cold, Southward)
Location: Eastern North Atlantic, off the coast of
Spain and Northwest Africa
North Atlantic Drift (Warm, Eastward)
Location: Extension of the Gulf Stream toward
Europe
Atlantic Ocean Currents

Labrador Current (Cold, Southward)

Location: Western North Atlantic, along
Canada’s east coast
Brazil Current (Warm, Southward)
Location: Off the east coast of South America
Benguela Current (Cold, Northward)
Location: Southwest Africa
Effect: Slows southbound vessels; creates strong
upwelling zones
Pacific Ocean Currents

Kuroshio Current (Warm, Northward)

Location: Western Pacific, off Japan’s east coast

North Pacific Current (Warm, Eastward)

Location: Central North Pacific

California Current (Cold, Southward)

Location: Off the U.S. West Coast

Peru (Humboldt) Current (Cold, Northward)

Location: West coast of South America
Pacific Ocean Currents

East Australian Current (Warm, Southward)

Location: Off Australia’s east coast

South Equatorial Current (Warm, Westward)

Location: Near the equator, both Atlantic and
Pacific
Indian Ocean Currents

Agulhas Current (Warm, Southward)

Location: Off Southeast Africa

Somali Current (Seasonal, North/South)

Location: Off the coast of Somalia

West Australian Current (Cold, Northward)

Location: Off Australia’s west coast
Southern Ocean & Arctic Currents

Antarctic Circumpolar Current (Cold,

Eastward)
Location: Circling Antarctica

East Greenland Current (Cold, Southward)

Location: Off Greenland’s east coast
 VIDEO:
Ocean Current 1 and 2
 Effects of Ocean Currents on Navigation

Ocean currents have a significant impact on

maritime navigation, influencing vessel speed, fuel
consumption, route efficiency, and safety.

Understanding these effects is crucial for route

planning and operational efficiency.
1. Impact on Speed and Fuel Efficiency

Favorable Currents

 Increase a vessel’s Speed Over Ground

(SOG), reducing travel time.
 Decrease fuel consumption, improving
cost efficiency.
1. Impact on Speed and Fuel Efficiency

Adverse Currents (Opposing Currents)

 Decrease SOG, causing delays and higher

fuel consumption.
 Can force vessels to adjust routes or
increase power usage.
2. Drift and Set (Course Deviation)

Drift: The sideways movement of a vessel due to

currents.
Set: The direction in which a current pushes a
vessel.

Compensation Required:
Mariners must adjust course headings to
counteract drift.
3. Effects on Routing and Passage Planning
Optimal Route Selection: Ships plan routes to
take advantage of favorable currents while
avoiding adverse ones.
3. Effects on Routing and Passage Planning

Seasonal Considerations: Some currents change

due to monsoons, El Niño, or seasonal wind
patterns.

Example: Indian Ocean - During the summer

monsoon, strong winds blow from the
southwest, driving surface currents in that
direction. In the winter, the winds reverse,
blowing from the northeast, and the surface
currents follow suit
4. Safety and Hazard Considerations

 Strong Currents and Heavy Seas

Can create rough conditions and increase the
risk of capsizing.
Example: The Agulhas Current off South
Africa is notorious for extreme wave conditions.

 Iceberg Transport
Cold currents like the Labrador Current
transport icebergs into shipping lanes, posing
collision risks (e.g., Titanic disaster).
5. Port Entry and Coastal Navigation

 Tidal Currents Impact Maneuvering

Ships must align port arrivals with slack tide to
avoid strong tidal currents.
Example: The English Channel has strong tidal
flows that affect vessel speed and maneuvering.

 Anchoring Challenges
Strong currents make anchoring difficult,
requiring additional precautions.