ETA Current/Wind Compensation Calculator

Input Pattern

Enter values in the left panel, keep units explicit, run the calculation, then copy or share the result. Invalid fields are highlighted immediately.

How to use this tool

1. Enter route distance and calm-water speed.
2. Input current component (head current positive) and wind speed penalty percentage.
3. Run the calculator and compare compensated ETA against calm-water ETA.

Worked example

Updating ETA in adverse conditions

• Distance: 80 nm
• Calm-water speed: 10 kn
• Head current: 1 kn
• Wind penalty: 10%

Result: The compensated ETA increases because effective speed is reduced by both current and wind penalty.

Compare the result with observed speed over ground and update it as conditions change along the route.

How to interpret the result

• Effective speed is a simplified planning value, not a full performance model.
• Head current and wind penalty reduce speed made good; favorable current can improve ETA if entered accordingly.
• Weather, sea state, RPM limits, course changes, and current variation can change the real arrival time.
• Use observed speed over ground and updated forecasts to refine the result during planning.

Common mistakes

• Treating one current value as constant over a long route.
• Applying a wind penalty without checking whether course changes alter the apparent effect.
• Forgetting schedule margin for traffic, pilot windows, tide gates, or speed restrictions.
• Using calm-water speed when fouling, load, or sea state has changed vessel performance.

FAQ

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