RedactedNarrative: Vessel 1 operating at slow no wake speed and Operator noticed water coming in boat and sinking fast.  Operator then went to back and checked to see that plug was still in and it was.  Operator then went back to the controls where the passenger was not seated and when he did the boat capsized.  They then ended up drifting to about 4 feet of water where boat came to rest on bottom, they could see no damage to the hull and thought the hoses to the live well possibly came apart and was pumping water into the boat.