RedactedNarrative: The vessel was trolling on Bighorn Lake within the Bighorn Canyon National Recreation Area near Dayboard 16. The vessel had 3 persons onboard including the primary operator. While trolling the operator stated he heard a pop followed by a boom/explosion come from the inboard engine which then caught fire. All three persons immediately jumped into the water and swam to the shoreline. once on  shore they waited approximately 30 minutes until waiving down another vessel which was able to rescue the 3 individuals. the vessel was found sunk in 58 feet of water on the day of the accident by US Park Service Rangers.