Last updated: 2026-04-14Contact: developer@captaincalc.com.tr
Reference basis: IMO/COLREG/STCW concepts, nautical practice, approved ship documents, and CaptainCalc calculation notes. Always verify operational decisions with official sources.
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Distance to Horizon & Radar Range
Calculate visual horizon distance and radar horizon range based on Height of Eye above sea level.
Formula reference & notes
Visual horizon (Bowditch): D = 2.07 × √HE (NM, HE in metres)
Radar horizon: D = 2.21 × √HE (NM, HE in metres)
⚠ Radar horizon shown is for own antenna height only. The actual detectable range of a target also depends on the target's own height above sea level. To find the combined radar range, calculate separately for own antenna and target height, then add the two results (Dipping Distance method).
Radar horizon: D = 2.21 × √HE (NM, HE in metres)
⚠ Radar horizon shown is for own antenna height only. The actual detectable range of a target also depends on the target's own height above sea level. To find the combined radar range, calculate separately for own antenna and target height, then add the two results (Dipping Distance method).
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