The fire broke out on a 19-foot Sea Ray shortly before noon on Wequaquet Lake and quickly spread to the second boat causing both to become fully engulfed.
The owner saw the flames spark in the motor and said he was unable to extinguish them on his own.
Firefighters battled the intense flames as they worked to tow the burning boats toward a ramp on Shoot Flying Hill Road.
The road was closed for almost two hours as crews worked to extinguish the blaze.
No one was hurt.
The cause of the fire remains under investigation