RedactedNarrative: V1 owner/operator was underway traveling eastbound through the entrance into bishops harbor located within manatee county florida. Operator estimated his speed at less than 10 mph. Operator advised he turned around and noticed his vessel's transom being over taken with sea water. Operator attempted to get onto a plane to prevent further water intrusion, but stated he was not able to due to the amount of water already inside his vessel. Operator stated his bilge pump was working and activated. Operator motored toward a small island within the harbor for safety. He was not able to reach the island and stated within minutes, the vessel was overtaken with sea water up to amidships and immediately rolled over and capsized. 
  
  Subjects held onto the capsized vessel while occupant swam to the nearby island approximately 30 yards away. No one donned their life jackets. A good samaritan in a vessel observed the capsizing and placed all parties within his boat. There were no injuries reported. 
  
  Manatee county sheriff's office received a 911 call and responded by water and arrived within 10 minutes of the call. The manatee county sheriff's office patrol vessel then placed all parties onto their boat awaiting my arrival to investigate the accident. 
  
  I was unable to inspect the vessel as it was underwater. Operator stated a failure of a thru-hull fitting is the suspected cause of the accident. The vessel was not able to be recovered until the following day due to the owner's arrangements with sea tow.