Why didn't MV Holiday Island sail in 2016, and could that have been avoided?

Transport Canada Marine Safety and Security documents that CBC News waited more than five years to receive, after filing a federal access to information request, say the corrosion that led to the suspension of MV Holiday Island in 2016 should have been found earlier. 

Repairs to extensive corrosion in the ballast tanks in 2016 meant the ship wasn't available until October of that season.

Instead, the Wood Islands, P.E.I., to Caribou, Nova Scotia, route was covered by one ferry, leading to a 15 per cent drop in traffic according to the ferry company, Northumberland Ferries. MV Confederation was making only six runs a day versus the company's usual nine when both ships were operational. 

And on days when MV Confederation suffered mechanical issues that season, there was no ferry service at all.

The water in ballast tanks helps keep a vessel level — something that's particularly important when loading a passenger ferry, said John Dalziel. The adjunct professor at Dalhousie University worked more than 50 years in the marine industry in ship construction and repair supervision, and as a safety inspector for Transport Canada Marine Safety and Security.

"You may have a big truck on one side and a motorcycle on the other, so it's going to lean over," he explained. "So you want to keep this under control." 

MV Holiday Island has been under Transport Canada's delegated inspection program since 2007. The vessel is owned by the federal government, in the person of whoever holds the job of transport minister. Northumberland Ferries is contracted to lease and operate the ship, and Lloyd's Register is contracted to do inspections on behalf of Transport Canada.

Corrosion of the ballast tanks was raised as a concern by Lloyd's Register inspectors in 2007 because the coating on the tanks was poor and these tanks are filled with saltwater, which is corrosive. Transport Canada officials say inspectors from Lloyd's, an engineering and technical services company based in the United Kingdom, said there would be annual inspections of the tanks to keep an eye on their condition. 

Given the age of MV Holiday Island, Dalziel said this corrosion needed to be tracked closely. 

"That was a very old ship. Most ships last 30 years," said Dalziel. 'It was 45 years — way past its normal life. And so you should look at that very carefully." 

The documents CBC News received through a federal access to Information request point to a Lloyd's inspection report from May 2015 that says all the tanks were inspected and their structural condition was good.

However, Transport Canada officials say, "it would appear reasonable to expect that some of the deficiencies noted where perforation and excessive corrosion is present and requires immediate repair ought to have been observable previous to May 2016 based on previous inspection."

Ultrasonic thickness measurements of the steel tanks revealed extensive corrosion during an inspection in Les Méchins, Quebec in June 2016. Officials said that kind of measurement exercise would have been warranted in 2012, but wasn't done. 

Dalziel said excessive corrosion like that seen on MV Holiday Island in 2016 doesn't happen overnight.