RedactedNarrative: On Oct 20, 2017 at approximately 2030 hours, operator and passenger were fishing approximately 150 yards northwest of Strawkis boat launch at Lake Sangchris. According to a written statement from Passenger (attached), they were at anchor and noticed the boat was taking on water.  They pulled up the anchor and headed towards the shore. The boat continued to swamp with water causing the bow to nosedive into the water. Operator and Passenger were then ejected from the boat into the water.  
  
  Passenger and Operator swam towards the dock when Passenger heard Operator yelling for help. Passenger swam back towards Operator and witnessed Operator bob up and down in the water. Passenger yelled to Operator to swim and hold onto the buoy but Operator was unable to, this was the last time Passenger saw Operator.
  
  Passenger held onto the buoy for approximately 20 minutes but could not locate Operator. Passenger removed his clothing and swam back to the boat dock. Passenger walked down the road and got help from a random driver. Passenger called 911 and was transported to the hospital and admitted for hypothermia. 
  
  On 10/21/17, Operator'' body was found at approximately 4:45 PM by the Sangamon County Search and Rescue team.  The Christian County Coroner''s office took possession of the body and a toxicology report was completed on10/30/17.  The coroner''s report indicated the death was due to drowning. 
  
  On Nov 30, 2017 at approximately 12:30 PM, I towed the boat and trailer involved in the accident to the east boat launch at Sangchris State Park. I ensured the plug was installed correctly and tied the boat to the trailer. I launched it approximately 20 feet from the dock. I got onboard and after approximately three minutes, the bottom of the boat showed water flowing in. I checked the plug and noticed some water near the plug, but no movement of water coming in from the plug. The water seemed to be coming from under the carpeted area near the stern. After approximately 20 minutes from initial launch; the boat had approximately 4 inches of water inside. 
  
  I recovered the boat moved it and the trailer onto a level surface. I began to look underneath the boat and found an X-shaped crack where the hull of the boat rides on a caster when it is trailered. The trailer had four casters installed upside down on the trailer in order to make recovery of the boat easier. The hull had dull colored spots where the boat rested on the casters. 
  
  The investigation revealed that the polymer casters used in construction of the homebuilt trailer contributed to the boat swamping with water. The hull of the boat is aluminum and the casters used were polymer, a much harder material than aluminum. Anytime the boat was transported on the homebuilt trailer, the hull bounced onto the caster repetitively. These small impacts caused a weakening of the hull and a crack developed. Water entered the vessel through the crack and eventually swamped the boat.
  
  There was no capacity plate inside the boat. I calculated the capacity of the boat using the formula determined by the National Marine Manufacturers Association; (Number of people = vessel length (ft.) x vessel width (ft.) ÷ 15). The capacity of the Polarcraft boat was 600 lbs. Factoring in the weight of the occupants (Operator = 213 lbs, Passenger = 175 lbs) and the weight of the equipment (approximately 100 lbs), the boat was not overloaded.
  