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Nighttime navigation relies heavily on lights as they are the only way we have to verify the electronics (GPS, radar, depth sounder). The keys to navigation by lights is to be able to identify the light, which requires specific chart reading skills, and then to predict the visible range of the light in the prevailing atmospheric conditions and eye heights.
Chart Trainer covers these subjects. Do you know that there is no number or value that you can read from the chart alone that will tell you how far you can see a specific light? We must always do a simple computation and then comparison to make this evaluation.
This resource of Chart Trainer explains the various light characteristics and provides animated demonstrations of their flashing patterns. The actual lights are simulated on the horizon insert while the developing pattern is plotted out on the screen. In this picture, the animation is just finishing. Note there is an option to increase the presentation speed for the slower lights. There is a set of Notes for each light type, and this extensive resource covers all light types in common usage.
The light shown in this example is one that is particularly difficult to predict without some guidance or direct reference to the USCG Light List — always a good idea in any event.
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