RedactedNarrative: V1 put in using the boat ramp on the Iowa River at Greencastle Avenue to go fishing the evening of 06/26/2022.  V1 had a surf drive motor. At approximately 12:30am on 06/27/2022, V1 traveled back to the boat ramp at Greencastle Avenue. As they approached the boat ramp, they had to travel underneath the Greencastle Bridge and as they were under the bridge, the current caused the boat to turn parallel to the bridge and the motor hit the bottom of the bridge. The motor hitting the bottom of the bridge caused the side of the boat to dip under the water. Water entered the boat and caused the boat to capsize and sink. Operator and Passenger were able the use the lattice structure of the bridge and make their way back to shore. After the incident, the boat sank and floated .7 miles downstream and was not found again until approximately 15 days later.  On 7/11/2022 during routine patrol, seasonal employees located the boat and arrangements were made to recover the boat on 7/15/2022. Between 7/11-7/15 someone came upon the sunken boat and removed/stole the surf drive motor off the boat. Upon recovery of the boat on 7/15/2022, it was discovered that the motor had been stolen and footprints in the mud indicated such activity. The Iowa River Marengo river stage water monitoring system at 12am on 06/27/2022 was 9.75 feet with a flow of 2,929 cubic feet per second. Flood stage at Marengo is 15 feet.