What the CTS line means
The water-track vector is the course to steer in true degrees before leeway and compass corrections.
Learn and practice course to steer
Start with a tide-only, one-hour example that explains every line. Then construct the vector yourself with immediate feedback before exploring leeway, variation and deviation.
| Level | Practice | Watch for |
|---|---|---|
| Day Skipper | Single CTS vectors with tidal set, drift, boat speed, and ground track | Plotting tide in the wrong direction or from the wrong point. |
| Coastal Skipper | Longer legs, changing streams, leeway, and passage constraints | Solving the maths but missing the practical decision. |
| Yachtmaster | Integrated CTS, EP/DR, fixes, electronics, and weather/tide judgement | Failing to explain assumptions and cross-checks. |
Course to steer vector tool
Learn the tide triangle, then build one yourself
Start with one tide-only example. See why a direct heading misses, construct the answer one vector at a time, then add leeway and compass corrections only when you are ready.
Live vector plot
One-hour CTS construction
True bearings
- Ground track
- 090 TGiven from A
- Tidal vector
- 180 T · 1.2 nmSet and drift · A to B
- Boat-speed arc
- 5.0 nmRadius centred on B
- Water track · CTS
- Solve from the plotRevealed after plotting
- 1
Plot tide
Set and drift from the start.
- 2
Swing arc
Boat speed from tide end.
- 3
Read CTS
Direction B to C, applied at A.
- 4
Correct
Leeway, variation, deviation.
Why tide is first
Boat movement and tidal movement happen during the same hour. Placing their vectors head to tail is a construction method, not the order the boat moves.
When to correct
Keep the plot in True first. Only after the CTS is solved should you adjust for leeway, variation, and deviation.
Learn the physical problem before calculating
See where steering directly along the desired ground track would put the boat after the tide acts. This makes the need for a correcting water track visible before bearings are introduced.
Keep true, magnetic, and compass separate
Solve the navigation problem first, then apply variation and deviation carefully. Mixing these too early makes the answer hard to audit.
Use advanced revision for multi-hour work
Coastal Skipper and Yachtmaster chartwork add changing tidal streams, leeway, fixes, and practical judgement around the plotted answer.
Common questions
What is a CTS vector triangle?
It is a plotted triangle that combines tidal stream, boat speed through the water, and intended ground track to find the course to steer.
When should I move from Day Skipper CTS to advanced CTS?
Move on when single-hour CTS feels reliable and you can explain tide, leeway, and compass correction without guessing.
Choose the revision route that matches what you are studying now.
Access is course-specific unless a bundle clearly says otherwise. Each brand stays on its own domain inside the Compass Revision Network.