Reflective flag.

I put a few on each side for night paddling along with solas tape

That’s great as long as you are planning to be seen by boats that have someone on board shining lights out over the water, and it’s definitely a good thing if your are reported missing and someone goes searching for you. No normal boaters that travel without forward-shining lights will see it.

They can see the flags in the daylight. Works like any Solas tape.

My all around white nav light on the center console lights up reflectors pretty good. Of course, I’m looking for them and have the cockpit lights turned down.

I have reflective tape all over my stuff, partly because it will reflect some sunlight during the day thus improving my visibility. But the main reason is, as @Guideboatguy mentioned, to be extremely visible in a nighttime search. When I’m walking around camp at night with a headlamp, even a few hundred metres away from the boat it picks up the light from my headlamp and glows much more than the surroundings.

I add reflective tape and sometime LED battery tent-lights to my boats not for the powerboats, they are either too fast or running without lights anyway, but because when I am night paddling, it is comforting to sweep the water with my flashlight to find the other kayaks and know how far we have drifted apart so we can join up.

I have Solas tape on all my boats in multiple locations and on my paddle faces and shaft.