seems like the problem could be solved fairly cheaply with machine learning. Just have cameras covering common areas for falls and have a model that identifies human like objects and then shoot off a signal to a human to verify, then if it's actually a person who fell over board send someone in a jetski or something to retrieve them

Also remind's me of patrice O'neal's rock coat joke 13 minutes in(NSFW)

https://www.youtube.com/watch?v=V-4k2SOD1P8