Four Fire Service appliances were called to the Fryatt St wharf in Dunedin about 8.20pm, after reports of fire on MV Tiakina.
Owner Lindon Colloty said it was lucky he and others were on board the ship at the time to raise the alarm.
"It’s a good thing I was. If I wasn’t, it could have been a whole different story," he said.
A fixed firefighting system on the ship had helped suppress the fire and minimise damage.
"We are still operational," he said.
"After this Easter break, we should be right.
"It will be all shipshape very soon."
It appeared the fire started inside a battery charger in the engine room.
It had caused minor electrical damage and was limited to the engine room.
Everyone on board the ship at the time was fine and there would be no effect on the charter business.
A Fire Service spokesman said firefighters from Dunedin Central, St Kilda and Willowbank attended the incident.
"The fire was out when we arrived," he said.
"We did a search just to make sure everything was fine and then blew the smoke out with a fan."
The luxury launch has been operating as a charter since 2009.
Tiakina was built at a shipyard at Bideford in England in 1953.
It arrived in Wellington the following year.
