The main North Atlantic currents
1The lesson in plain words
The North Atlantic gyre combines fast western currents with slower eastern currents. Use pilot charts for typical rates and recent analyses for changes.
The loop
Follow the clockwise subtropical loop: North Equatorial Current west towards the Caribbean; Florida Current and Gulf Stream north and north-east; an eastward return through the Azores Current, south of the Azores; then Canary Current south-west towards the tropics. The North Atlantic Current branches north-east from the Gulf Stream system towards northern Europe.
Gulf Stream
According to NOAA, the Gulf Stream averages about 3.5 knots, reaching about 5 knots at the surface in its core. It is about 100 km wide. Further north it widens, meanders and slows to under 1 knot. It also sheds warm and cold eddies—rotating patches of water that can change current direction and speed.
The eastern side
The North Atlantic Current carries water north-east towards Europe in several branches; speed varies by branch and location. The Azores Current, south of the Azores, averages only about 0.2 knots, with faster jets. The Canary Current flows south-west along Africa and the Canaries at about 0.2–0.6 knots. The North Equatorial Current, between about 10° and 20° N, sets west at only about 0.2–0.3 knots on average, helped by the trade winds.
Using currents on passage
The classic trade-wind route from the Canaries to the Caribbean uses the Canary and North Equatorial Currents and the trade winds together. Returning, yachts sail north towards Bermuda and the Azores to use the westerlies. Pilot charts and routeing guides give average set (flow direction) and rate (speed) by month. Recent current analyses estimate the Gulf Stream’s path and eddies; check their valid time.
Currents and your position
Set is the direction a current flows towards; drift, or rate, is its speed in knots. A 0.5-knot current carries you 12 nautical miles in 24 hours. Dead reckoning estimates your position from a known position using course, speed and elapsed time. Apply the current to your dead-reckoned position to obtain an estimated position. Compare this with your observed position: the actual current may differ from the monthly average.
2Key data
- Gulf Stream (NOAA)
- Average about 3.5 kn; core up to about 5 kn
- Gulf Stream width
- About 100 km
- North Atlantic Current
- North-east towards Europe; speed varies by branch and location
- Azores Current
- About 0.2 kn on average, with faster jets
- Canary Current
- About 0.2–0.6 kn, setting south-west
- Drift example
- 0.5 kn for 24 h = 12 nm
3Key points
- 1
Subtropical loop: North Equatorial → Florida/Gulf Stream → Azores → Canary. North Atlantic Current branches north-east.
- 2
The Gulf Stream averages about 3.5 knots and reaches about 5 knots in its core.
- 3
Eastern currents are slow: the Canary Current runs at about 0.2–0.6 knots.
- 4
Use pilot charts for monthly averages and recent current analyses for changes; check each product’s valid time.
- 5
Half a knot for a day is 12 nautical miles: allow for it.
4Frequent mistakes
Wrong: The Gulf Stream is a steady river in a fixed place.
Right: It meanders and sheds eddies. Check a recent current analysis before you cross it.
Wrong: A current of half a knot is too small to matter offshore.
Right: Half a knot for 24 hours is 12 nautical miles. Apply the current to your dead-reckoned position to obtain an estimated position.
5Practice case & exam keys
Your south-west passage is 850 nm at 6 knots through the water. A pilot chart shows an average 0.4-knot following current. Your crew promises arrival nine hours earlier. Is that a sound promise?
Show the answer
It is a useful estimate, not a promise. A constant following current would give 6.4 knots over the ground: about 133 hours instead of 142. But the chart gives a monthly average. Check observed progress with satellite navigation (GNSS) and recent current information before relying on that arrival time.
Exam keys
- Clockwise subtropical loop: North Equatorial west → Florida/Gulf Stream north and north-east → Azores east → Canary south-west. North Atlantic Current branches north-east towards Europe.
- Gulf Stream: average about 3.5 kn, core about 5 kn (NOAA), meanders and eddies.
- Eastern currents slow: Canary about 0.2–0.6 kn; current displacement = rate × time.
Finish this unit
When you've read it, answer three questions. Get all three right to finish the unit; opening the page alone doesn't count.
My notes for this unit
No notes