NAVIGATION TOOLS
Navigation Calculators
Professional navigation calculators for ETA, collision avoidance, sailing calculations, tide heights and compass corrections.
All Navigation Calculators
← Back to CalculatorsETA Calculator
Calculate estimated time of arrival based on distance, speed, and departure time
ETA = Departure Time + (Distance ÷ Speed)
CPA / TCPA Calculator
Closest Point of Approach and time to CPA using relative velocity vectors
CPA = |Own Pos - Target Pos| × sin(θ_rel)
Great Circle Distance
Shortest distance between two geographic positions on the earth's surface
D = 2R · arcsin(√(sin²(Δφ/2) + cos φ₁·cos φ₂·sin²(Δλ/2)))
Speed–Time–Distance
Solve the STD triangle for voyage planning and passage calculations
Speed = Distance ÷ Time | Time = Distance ÷ Speed | Distance = Speed × Time
Mercator Sailing
Calculate course and distance using D.Long, departure, and meridional parts
Course = arctan(D.Long ÷ DMP) | Distance = D.Lat ÷ cos(Course)
Tide Height – Rule of Twelfths
Calculate intermediate tide height at any given time using rule of twelfths
Rise per hr: 1/12, 2/12, 3/12, 3/12, 2/12, 1/12 of tidal range
Compass Error by Celestial Bodies
Determine compass error by comparing true and compass bearings of celestial bodies
Compass Error = True Bearing − Compass Bearing
Course to Steer – Current / Leeway
Calculate the course to steer allowing for tidal stream, current, and leeway
CTS = Course Made Good ± Current Correction ± Leeway
About Navigation Calculators
These navigation calculators are designed for STCW-certified officers and navigators. They cover the most common calculations performed on the bridge — from simple ETA computations to complex collision avoidance geometry. All calculations follow standard maritime practices as outlined in Bowditch, Reeds, and IMO guidelines.