Course Made Good

What is Course Made Good?

In nautical navigation, Course Made Good (CMG) is the actual path a vessel travels over ground, factoring in wind, current, and steering adjustments. It’s the true track—not what you planned on the chart, but what you really sailed.

It reflects the reality of life on the water:
⛵ Adapting to changing conditions.
🧭 Adjusting when the wind shifts.
⚓ Learning from every leg of the journey.

CMG is about progress, not perfection—a record of how you got there, not just where you aimed to go.

⚓ Nautical Definition of Course Made Good

The actual course you travel over the ground from your starting point to your current position.

🧭 Broken down:

• It’s the resultant direction over ground, taking into account:

  • Current

  • Wind

  • Leeway

  • Steering errors

  • Anything else that affects your path

It’s not necessarily the course you steered (compass heading) — it’s what actually happened.

📐 Example:

• You steer a course of 090° (due east) for 10 miles.

• There’s a 2-knot northerly current.

• Your actual track over the seabed ends up being closer to 080° — that’s your Course Made Good (CMG).

⚠️ Commonly confused with:

TermMeaningHeadingWhere the bow is pointingCourseIntended path over groundTrackPath actually followedCourse Made GoodActual course over ground from start point to end pointSpeed Made Good (SMG)Net speed over ground between two points

In navigation, CMG is crucial because:
✅ It tells you how effective your steering was.
✅ It’s used to calculate position fixes and ETA.
✅ You’ll find it on your GPS/plotter as part of Course Over Ground (COG) — although some sailors distinguish CMG (start to current point) from instantaneous COG.

If you’d like, I can also explain how to calculate CMG & Speed Made Good from DR plots, or show how to read it from GPS in a race or passage context. Want that?