The boat fire took place around 4:30 pm, near Kershaw Park, at the north end of the lake.
Ontario County Sheriff's deputies said the department's marine unit was on scene in less than one minute.
Firefighters escorted to the boat were able to use fire extinguishers to put the flames out, according to deputies.
The four people on board, along with their three dogs, all managed to escape.
The cause of the fire appears to be an accident, due to a mechanical issue.
According to deputies, Eugene Allaire, 56, said when he started the boat, the engine compartment and rear floor area caught fire.