🧭 Parallel Sailing Calculator
Calculate course, distance, D'long, and departure for parallel sailing — when sailing due East or West along a parallel of latitude. Includes two modes, interactive map, and step-by-step solutions.
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Calculation Mode
Coordinate Format
⏳ Results
🧭
Calculation results will appear here.
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⚙️ How to Use
Mode 1 – Find Course & Distance
- Enter the Initial Position (lat & lon)
- Latitude auto-populates for the final position
- Enter the Final Longitude
- Click Calculate to get course and distance
Mode 2 – Find Final Position
- Enter the Initial Position (lat & lon)
- Select Course: 090° (East) or 270° (West)
- Enter the Distance in nautical miles
- Click Calculate to find the final longitude
✅ When to Use
- Sailing directly East or West
- Both positions on the same latitude
- Quick calculations for short passages
❌ When NOT to Use
- Different latitudes → use Plane Sailing
- Long ocean passages → use Great Circle
- Curved/rhumb-line courses → use Mercator Sailing
💡 Example
Given:
- • Initial: 35° 42.7' N, 120° 32.7' E
- • Final: 35° 42.7' N, 150° 35.4' E
Result:
- • Course: 090° T (East)
- • Distance: 1,463.73 NM