Seaport To Port Distance Calculator

Great Circle Distance Formula:

\[ Distance = R \times \arccos(\sin(\phi_1) \times \sin(\phi_2) + \cos(\phi_1) \times \cos(\phi_2) \times \cos(\Delta\lambda)) \]

Port 1 Latitude:

Port 1 Longitude:

Port 2 Latitude:

Port 2 Longitude:

Distance (nm):

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1. What is Great Circle Distance?

The Great Circle Distance is the shortest distance between two points on the surface of a sphere, measured along the surface of the sphere. For maritime navigation, this represents the most efficient route between two seaports.

2. How Does the Calculator Work?

The calculator uses the Great Circle Distance formula:

\[ Distance = R \times \arccos(\sin(\phi_1) \times \sin(\phi_2) + \cos(\phi_1) \times \cos(\phi_2) \times \cos(\Delta\lambda)) \]

Where:

\( R \) — Earth's radius (3440.065 nautical miles)
\( \phi_1, \phi_2 \) — Latitudes of the two ports in radians
\( \Delta\lambda \) — Difference in longitudes in radians
\( \arccos \) — Inverse cosine function

Explanation: The formula calculates the central angle between the two points and multiplies by the Earth's radius to get the distance.

3. Importance of Nautical Distance Calculation

Details: Accurate distance calculation is crucial for voyage planning, fuel estimation, arrival time prediction, and optimizing shipping routes to minimize costs and travel time.

4. Using the Calculator

Tips: Enter latitude and longitude coordinates in decimal degrees. Latitude ranges from -90° to 90°, longitude from -180° to 180°. Positive values for North/East, negative for South/West.

5. Frequently Asked Questions (FAQ)

Q1: Why use nautical miles instead of kilometers?
A: Nautical miles are the standard unit of measurement in maritime and aviation navigation, based on the Earth's circumference.

Q2: How accurate is the great circle distance?
A: The calculation provides the theoretical shortest distance. Actual sailing routes may vary due to currents, winds, and navigational constraints.

Q3: What coordinate format should I use?
A: Use decimal degrees format (e.g., 40.7128° instead of 40°42'46"N). Most GPS systems and charts provide coordinates in this format.

Q4: Can I use this for air travel distance?
A: Yes, the same formula applies to air navigation, though flight paths may be affected by air traffic control and weather routing.

Q5: What is the maximum error in this calculation?
A: The formula assumes a perfect sphere. The Earth is actually an oblate spheroid, but the error is typically less than 0.5% for most practical purposes.