RedactedNarrative: An 18' center console livery vessel capsized near the Seven Mile Bridge, Marathon, Monroe County, Florida. The renters were drift fishing along the bridge when the vessel became swamped from the stern. When the operator put the vessel in forward gear, the vessel capsized placing the three POB in the water. I then made contact and interviewed Operator at Tranquility Bay Resort. He advised they were drift fishing near the 7 Mile Bridge. They would head off shore from the bridge about 3/4 of a mile, turn the engine off and fish while drifting back towards the bridge. They had done this 2 or 3 times prior to V1 taking on water and capsizing. Immediately prior to V1 capsizing, Occupant1 noticed the stern of the vessel was filling up with water. He informed his dad, Operator, who instructed Occupant1 and Occupant2, to move forward on V1. He then started the engine, placed the vessel in forward gear, but when he did the vessel rolled to starboard and all three persons on board fell into the water. All three then swam to the nearest piling under the bridge without PFDs on and were picked up on V2. Operator stated all three of them were in the water for a few minutes before being picked up; he estimated between 5 -15 minutes. USCG small boat from Marathon arrived shortly after, and then we arrived on scene. 
  
  Officer asked Operator about the rental process and his previous vessel operation experience. Operator stated most of the business was conducted between himself and subject. Operator took delivery of the vessel from a private residence and was given approximately an hour of vessel, safety gear, and area orientation from KCB Boat Rentals. Operator said all the safety gear was aboard V1 and Rental staff showed them where it was all located. Operator said he had rented and used similar vessels multiple times while visiting the Keys and estimated his vessel usage time to be approximately 40 hours on similar vessels. He also stated he previously owned a 28' vessel and used it approximately 15-20 times per year during the time he owned it. Operator also indicated they had problems with the rented V1 the day before. He said the livery had to tow the vessel back to shore because a seal had broken around the propeller and V1 would no longer make way in the water. 
  
  Based upon observations of the vessel and conditions, causes may have been multiple variables. The wind and tidal current were opposing causing a standing chop on the surface of the water. The vessel has a low transom where the engine is mounted. Chop plus low transom may have accounted for the stern becoming swamped. It is unknown if the bilge pumps were operational at the time of the capsizing of V1.