HALIFAX - A massive cruise ship carrying 2,770 people narrowly missed a smaller tour boat in thick fog last summer in Halifax Harbour, a new report says.

The Transportation Safety Board report, released Thursday, says the Summer Bay, with 39 people on board, crossed the bow of the cruise ship Grandeur of the Seas with just 25 metres to spare.

It says the smaller boat's captain made a number of mistakes — he thought there was other traffic in the harbour when he misinterpreted radar data, but didn't slow down or take other steps to verify the information. It also says he was incorrect about his location in the harbour at a time when visibility was restricted to between 100 and 200 metres.

"The Grandeur of the Seas bridge team was unaware that the Summer Bay was crossing their bow until the pilot saw the Summer Bay's mast as it appeared from underneath the bow on the starboard side, after it had already crossed," said the report.

The two crossed paths on June 29, 2016, at 9:42 a.m. in the outer harbour between McNab's Island and Purcell's Cove.

The 238-metre Grandeur of the Seas, owned by Royal Caribbean and based in Baltimore, is a regular visitor to the harbour; the 15-metre Summer Bay is a day-tour boat run by Murphy's the Cable Wharf, Halifax's largest tour boat company.

The captain of the Summer Bay, going 7.5 knots, told the pilot of the cruise ship, going 10 knots, that it "would keep well clear by staying to the west of the Grandeur of the Seas." But the captain changed course and the big ship's bridge team lost the target on their radar screen due to proximity.

"The TSB's investigation into the close-quarters crossing between the Summer Bay and the Grandeur of the Seas determined that the master of the Summer Bay misinterpreted radar data and made a decision to cross the bow of the Grandeur of the Seas with insufficient information," the report said.

"The Grandeur of the Seas bridge team was unaware of the Summer Bay's sudden course alteration, but, even if they had been aware of it, the size and manoeuvrability of their vessel meant that they would not have had time to react effectively."

There was no collision and no one was hurt, the report says. The cruise ship reported the incident to authorities after docking at Pier 20 as planned.

The report says Murphy's has added automatic identification units to most of its boats, developed standard operating procedures for its vessel captains in reduced visibility conditions, and commissioned an external audit of its safety management system.

News from © The Canadian Press, 2017