What the CTS line means
The water-track vector is the course to steer in true degrees before leeway and compass corrections.
Course to steer practice
Course to steer questions test whether you can allow for tidal stream, boat speed, intended ground track, leeway, and compass correction. The process is visual, so repeated vector practice matters.
| 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
Build the CTS triangle in the right order
Plot tide first, swing the boat-speed arc from the end of the tide vector, read the water track as CTS true, then apply leeway and compass corrections.
Live vector plot
One-hour CTS construction
True bearings
- Ground track
- 090 T · 4.9 nmA to C
- Tidal vector
- 180 T · 1.2 nmSet and drift · A to B
- Boat-speed arc
- 5.0 nmRadius centred on B
- Water track · CTS
- 076 TSteer B to C
- 1
Plot tide
Set and drift from the start.
- 2
Swing arc
Boat speed from tide end.
- 3
Read CTS
Tide end to ground-track crossing.
- 4
Correct
Leeway, variation, deviation.
Why tide is first
The boat will be carried by the stream for the hour, so the water-track vector starts at the end of the tide vector.
When to correct
Keep the plot in True first. Only after the CTS is solved should you adjust for leeway, variation, and deviation.
Draw the vector triangle before calculating
CTS is easier when you draw tide, water track, and ground track as a triangle. Rushing straight to arithmetic causes direction errors.
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.