Honestly, they should be reflective, and designated not only by red/black but also by shape.
If you are boating at night, I highly recommend the SiOnyx Aurora sport. Most nights it works pretty well. I’ll post a video from the 4th somewhere around 10:30-11pm. On a moonless night it doesn’t work as well, but still enough light from houses etc to ID stuff in the water.
(Apologies for the video, people were just using the camera to look around- so- it’s akin to a 1990’s camcorder video pointed at the ground etc. )
https://youtu.be/vaZtxqQ2y8s