Marine Atlantic spokesman Darrell Mercer said the fire started in the emergency generator compartment.
Crew quickly extinguished the fire. There were no passengers aboard at the time.
Two crewmembers were taken to hospital as a precaution with possible signs of smoke inhalation. They were seen by a doctor and released later that day.
Mr. Mercer said it is believed some residual oil in the compartment caught fire during the drydocking process.
“The fire had no impact on the refit schedule, which is estimated at four weeks,” said Mr. Mercer.