Visibility Distance at Sea: The Science of Horizon and Object Detection

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We're currently updating this guide with detailed diagrams and illustrations to enhance your understanding of visibility at sea.

In the meantime, please enjoy our interactive calculator below and reference the quick formulas in the sidebar.

Quick Visibility Calculator

Use this calculator to quickly determine horizon distance and object visibility based on heights. Adjust the sliders to see real-time changes in visibility distances.

Height Units:

Distance Units:

Preset Object Heights:

Observer Height: 6 meters

0 25 50 75 100 m

Object Height: 50 meters

0 125 250 375 500 m

Horizon Distance

8.7 kilometers

Maximum distance you can see to the horizon

Object Visibility

34.0 kilometers

Maximum distance you can see the object

Using formulas: d = 3.57 × √h (km) or d = 2.08 × √h (NM) for horizon distance

Coming Soon: Comprehensive guide with illustrated examples of horizon visibility, object detection, and atmospheric effects.

Please check back soon for the full content!

Common Heights	Horizon Distance
Eye level (2m)	5.0 km / 2.9 NM
Ship bridge (15m)	13.8 km / 8.1 NM
Lighthouse (45m)	23.9 km / 13.9 NM
Mountain (300m)	61.8 km / 36.0 NM

Visibility Distance at Sea: The Science of Horizon and Object Detection

Content Under Construction

Quick Visibility Calculator

About Landmark Heights

Horizon Distance

Object Visibility