NauticTools2Coastal navigation
Current triangle – where does the stream set me?
A boat steering a course through the water is also carried along by the current. Its track over the ground is the sum of “speed through the water” and “current” – drawn as the current triangle. NauticTools2 solves all three classic problems, draws the triangle and shows the working.
- Course & speed through water
- Course & speed over ground
- Set & drift
- Current correction
- Plot
The three problems
Six values describe the triangle: course and speed through the water, set and drift of the current, and course and speed over ground. If four are known, NauticTools2 calculates the other two.
- Where will I end up? Known: course and speed through the water, set and drift – wanted: course and speed over ground.
- What do I need to steer? Known: course over ground, speed through the water, set and drift – wanted: the course to steer and the speed over ground.
- What is the current? Known: course and speed through the water, course and speed over ground (e.g. from GPS) – wanted: set and drift.
All three also give the current correction, the angle between course over ground and course through the water.
Example: what do I need to steer?
You want to make good a course of 068° over the ground. The log shows 4.5 kn, and the current sets 125° at 2 kn. Which course do you steer?
Course to steer 046° Speed over ground 5.3 kn Current correction 21.9°
Related tools
- Course Conversion – from compass course to course over ground
- Dead Reckoning – DR position from course and distance
- Distance, Speed and Time
NauticTools2 is free and runs on Windows 10 and 11. An Android version is in preparation.
Get it from the Microsoft Store