Rescuing someone fallen overboard from a boat

Step 8 Rescue at Night

If performing a rescue at night, use a floating light to mark the victim's position. It is almost impossible to see someone in the water in the dark. If you cannot see the victim, you should stop engines and try to listen for them.

We did not try a live exercise at night (too risky, not so much fun) but I cast a marker pole adrift.
The photo shows the pole about 100 metres away, illuminated by a plug-in spotlight. The reflective band around the float may be clearly seen, also a slight reflection from a small band on top of the pole.
There is also a lifebuoy, with reflective tape on the upper side, which was completely invisible - as would have been a person in the water. The floating light attached to the pole was easily visible when it flashed. The light attached to the lifebuoy was only visible when it was not obscured by the buoy itself.
This was in totally calm conditions; the lights were right at the water's surface and would have been easily obscured by waves.
When a small pocket flashlight was used, the reflector was visible to the eye but much dimmer - it would have been hard to see against any lighted background.