RedactedNarrative: Operator of vessel 1 (V1) stated he was traveling north in the St. Johns River in Brevard County when he realized his vessel was taking water. As operator saw water filling the vessel he throttled the motor up which resulted in the vessel flooding/swamping. Water moved to rear of vessel lifting the bow in a vertical direction, the motor quit, then V1 capsized to the bottom. 
  
  Operator advised that he was traveling north on the St. Johns's River when he looked down and saw water filling the vessel from the deck area. Operator made way to the nearest shoreline to see where the water was coming from. Operator stated that when he throttled up on the motor, water went to the back of the vessel causing the vessel to swamp and then capsize. Operator stated the motor quit on his vessel when the water went to the stern. Operator advised that he was the operator of the vessel and that the only passenger on board was his friend. Both men swam to the shoreline approximately ten yards away from the initial capsizing. Neither man was injured and both refused medical attention. I spoke with occupant who was able to confirm story. Both men denied consuming any alcohol and I observed no evidence of any impairment. 
  
  Once the vessel was able to be removed from the river bottom it was observed that a rivet had come loose on the vessel's hull. The missing rivet was just forward of center on the starboard side and approximately two inches from the bottom of the vessel, well under the water line. This hole caused the vessel to take water (see attached photos). Operator's throttling up on the motor moved the water to the back of the vessel causing more weight in the transom area simultaneously causing the vessel to swamp then capsize. Operator estimated the total loss of his vessel to be $2500.00. 
  
  Conclusion: In my investigation I found that hull failure (due to a 1/4 inch hole from the missing rivet) was the primary cause for this vessel swamping accident.