RedactedNarrative: On July 4, 2014 at 0915hrs, I was dispatched to the Stateline launch ramp, Wahweap District, Glen Canyon National Recreation Area, Page, Arizona, to investigate a boat fire.  On arrival I contacted the boat owner/operator who told me that he launched his boat at Stateline ramp just prior to 0800hrs, this date.  He set an easterly heading for Castle Rock cut.  After he was underway about 10 minutes he observed smoke coming from under his engine cowling.  He cut power and stopped the engine.  His son and wife were following in another boat.  He offloaded his spare fuel container to the other boat along with a kayak that was blocking access to the engine.  He removed the engine cowling and observed flames and heavy smoke.  He applied the entire contents of a single B1 dry chemical fire extinguisher and the fire rekindled.  He applied the contents of a second B1 dry chemical fire extinguisher on the fire then applied several buckets full of lake water to cool the engine block and exhaust manifolds.  
  He had his son tow the disabled boat back to Stateline launch ramp.  
  I inspected the boat and examined the engine compartment and cowling.  It appeared that the source of the fire was on the port side of the engine at the location of the port side exhaust manifold.  Ignition wiring, other engine wiring, hoses, and engine cowling insulation on the port side appeared to have sustained the most fire damage.  I photographed the boat and engine compartment to document the post fire conditions.  Other than the fire damage to the engine compartment, the boat appeared to be in a well maintained condition.