The phrase "red right returning" is used to remind vessels of what in the US aids to navigation?

The phrase "red right returning" serves as a mnemonic device to help boaters remember the proper navigation rules regarding the positioning of red buoys in relation to their course. When a vessel is returning to port or heading upstream, red buoys, which mark the right side of the channel, should be kept on the right (starboard) side of the vessel. This is particularly relevant in areas where the channel is marked by a system of buoys, as it ensures safe passage and prevents collisions or grounding. Properly following this guideline indicates a clear understanding of navigational aids, thereby ensuring safe boating practices.