RedactedNarrative: Vessel 01 (V01) was docked at the Saint John's River Marina dock #95. The owner stated that at approximately 4:30AM he woke up and noticed that the vessel was taking on a large amount of water and that the port side engine compartment was flooded. The owner notified the Marina and they responded with a barge and several pumps. They began to pump the water out of the vessel and stabilized it where it remained until this Investigator's arrival to the scene. 
  
  A witness stated that he had seen V01 sitting low in the water for the last two weeks.
  
  V01 was salvaged and towed by Boat U.S. to the Midway Marina in Astor
  
  03/31/2018, 0930 AM: A follow up inspection of V01 was completed at Midway Marina in Astor. The Marina mechanic stated that upon arrival at the Marina V01's two holding tanks were full and had to be emptied. After the holding tanks were emptied and the remaining water was pumped out V01 stabilized and stopped flooding.
  
  No damage to the pontoons of V01 was apparent.
  
  Upon inspection of the port side engine compartment it was noted that the engine exhaust vent was sitting one inch above the water line. The exhaust vent was not outfitted with any one-way valve type device. 
  
  It is this Investigator's conclusion that the concentration of weight on the port side of V01 (four adult occupants, two full holding tanks, fuel, and personal belongings) caused the engine exhaust vent to submerge below the water line resulting in a sudden flooding.
  