COLREGs Lights Shapes is an Android app developed by madeof.blue that provides a complete guide to the Colreg rules 20 to 31. The app offers a light and shape visual search engine, thematic rule reference, revision tests, and 3D rendering for each rule. With a touch and drag action, you can change the observation point on the 3D rendering view for each rule. The visual search engine allows you to find any Colreg rule in seconds.

The app is free to download with premium content, ad-free, and can be used offline. It is an excellent tool for maritime professionals and enthusiasts who want to learn and revise the Colreg rules without the need for an internet connection. With its comprehensive features, COLREGs Lights Shapes is a must-have app for anyone interested in maritime rules.