RedactedNarrative: The owner/operator of vessel A reportedly let the engine run for approximately twenty minutes prior to departing the Rock Creek Marina; it appeared to be running fine at that time. This was reportedly the first time vessel A had been used this season (2017) and it had recently been serviced by marina staff. After departing the marina and idling through the "no wake" area, the operator throttled up (gunned it). Then, after traveling approximately one hundred yards and getting up on plane, vessel A lost power. Smoke was then observed billowing near the stern/engine area. The operator then lifted the hatch covering the engine and observed a rolling flame. He then dropped the hatch, ordered the occupants to the forward section of vessel A, then waved down a passing vessel (unknown). After they boarded the unknown vessel, the operator observed the Halon system activate, which appeared to extinguish the fire. Vessel A was towed to the marina''s sailboat ramp thereafter.
  
  While NRO was inspecting vessel A, he observed a plastic bag stuffed in the fuel inlet and noticed that the gas cap was missing. The operator stated that someone had lost the cap when it was fueled. NRO also observed what appeared to be oil in the bilge, below the engine. Burnt fiberglass and wiring was also visible. 
  
  After consulting with four boat mechanics, NRO has reason to believe that the engine may have shut down due to a loss in pressure (hydraulic fluid leak) of the trim in the lower unit, possibly due to cracked or worn hoses. The fire may have started when the hydraulic fluid dripped or sprayed onto the engine block or exhaust manifold, thereafter.
  