Here is more info to fit into a timeline:
"Boaters whose vessels were docked nearby described the experience. The boat, which had a Grateful Dead sticker affixed, was, according to eyewitness, named 'The Ripple.' According to the group, who were sitting on the dock Wednesday morning, the man and Nolan-O'Slattara had been seen having a good time and 'partying' earlier on Monday.
They headed out on the water on another boat docked in the next slip, then returned and boarded 'The Ripple' Monday night.
Around midnight, two men said, they heard screaming and banging on the doors of the boats in the area as the man reportedly tried to get help.
'He woke us up,' one man said."
So
TENTATIVE timeline:
Daytime: Having good time on boat. Nolan and boyfriend leave on another boat.
Night: Nolan and boyfriend return to The Ripple.
Late night: Business meeting. Told boyfriend she'd uber home at 1am.
Before midnight?: People heard noise and screaming, boyfriend woke them up
Midnight: Someone called 911. Local police officers arrive.
4am: County police called.
"We dreamed big together, laughed harder than anyone else could understand, and built so much from nothing."
patch.com