The second-alarm fire started aboard the small passenger vessel docked at Commonwealth Pier in the Seaport District around 11:30 p.m., according to Boston Fire on Twitter.
Heavy smoke was seen coming from the lower levels of the boat, which was unoccupied at the time of the fire. While no injuries were reported, the fire did cause extensive damage to the ship, the Coast Guard reports.
"The investigation will allow for a full understanding of the events that led up to the fire and provide a way forward to prevent future events," the Coast Guard said in a statement.
Anyone with information is asked to email investigators at SpiritOfBoston@uscg.mil starting Saturday, April 1.
Click here to follow Daily Voice Lynn and receive free news updates.