RedactedNarrative: V1 rented pontoon recreational cruising with seven persons onboard. Less than an hour of operation, outboard engine caught fire. Extinguished with portable extinguishers and assistance from good samaritan commercial crab vessel. Livery returned V1 to shore and provided renter with replacement vessel. 
  
  operator heard a "prop noise" while in gear and underway. The crew looked at the motor and it was on fire. Attempts were made to turn the engine off at the ignition key, but the engine continued to run. There was no unusual smell of gasoline fuel/vapors, but there was a sheen on the water. 
  
  A good samaritan commercial crabbing vessel (FL2975PL) was operating nearby and saw the emergency. Subject pulled alongside and assisted with putting the fire out.  Subject also communicated the emergency via VHF CH 16 to USCG Mobile. Upon arrival, the commercial vessel had taken six persons onboard for safekeeping. Subject explained that he cut the battery cables.