RedactedNarrative: Operator was operating Vessel 1 (24ft CC Bay Boat with 250 O/B) in Lake Borgne. The outboard motor on Vessel 1 was experiencing some mechanical trouble. Operator knew what had to be done to correct the mechanical issue. The passenger Occupant maintained control at the helm while Operator went to the stern of the vessel to fix the mechanical issue. Operator had to remove the motor cover in order to make adjustments to the throttle cable. Meanwhile Vessel 1 was taking on water. Operator suspected it was from the self bailing hull back filling in addition to waves coming in from the stern of the vessel. The waves were estimated at 2 to 3ft in height. Once Operator was able to correct the mechanical issue, he regained control at the helm. Operator attempted to drive Vessel 1 in forward but it was too full of water. At this point Operator was only able to plow forward a little before Vessel 1 was full of water. Operator and Occupant grabbed several PFD's and put them on as well as joining the remaining PFDs together to help assist them. Operator and Occupant exited Vessel 1 as it sunk within seconds and then capsized. There were no injuries. Neither alcohol nor drugs are believed to be a contributing factor.