How long Skagway will be without ferry service remains unknown a day after the ferry dock sunk Thursday morning for reasons which also remain unclear.

Skagway Mayor Mark Schaefer explained in an interview late this morning officials suspect the failure of a waterline running through the floating concrete structure may have caused the catastrophic failure.

The dock is owned by the state and the Skagway Borough.

Engineers from the Alaska Department of Transportation flew in from Juneau Thursday to assess the situation.

They are still considering their options, Transportation spokesman Jeremy Woodrow said this morning.

The Alaska Marine Highway announced late Thursday that all scheduled ferry traffic to the community has been cancelled for the next two weeks.

Woodrow said the department is working as quickly as it can to put together a request for proposals to see if the dock can be re-floated, repaired or towed away.

There's no timeline when the RFP will go out the door to salvage companies and contractors but the matter is being treated with urgency, he said.

Ferry service to Skagway is said to be a life line for the community and the local economy, and without it, it's expected the impact will be substantial.

"It is going to hurt,” Jeff Brady, the longtime publisher of The Skagway News and owner of the Skaguay News Depot and Books, told the Star this morning.

Brady said his shop does good business with passengers of the large cruise ships which will begin arriving next week and are unaffected by the sinking of the ferry dock.

He does better business, however, with clients of the smaller cruise ships, the 100- and 200-passenger vessels which do tie up at the ferry dock, he pointed out.

The biggest customers for his book store, Brady noted, are the independent travellers arriving or leaving on the state ferry.

Traffic by independent travellers – who may or may not be staying for the night while they wait for their boats, who are in town spending money in restaurants and local businesses like his while they wait – are important to Skagway's economy, he said.

Brady said the ferry dock also provided moorage for larger yachts and other private vessels which pay fees to the Skagway Borough.

Alaska Marine Highway statistics show that in 2013, 24,000 ferry passengers got off in Skagway and 22,800 boarded. There were 7,600 vehicles – passenger cars to transport trucks – which arrived in Skagway by ferry last year, and 6,700 departed.

Ferry service to Skagway averages three to four times a week and everyday during the summer schedule, which will begin next week.

The concrete dock was partially submerged when Cory Bricker of the Alaska Highway Marine Lines arrived at work at 6 a.m. Thursday.

By 7:30 a.m., the dock had sunk.

The dock measures 49 metres (160 feet) by 37 metres (120 feet) and is 3.6 metres (12 feet) high.

It was kept afloat by 24 individual concrete chambers which are airtight and watertight, all of which had been inspected within the last two years.

The Skagway mayor said today they suspect a 7.6-centimetre (three-inch) line carrying potable water through the structure may have caused the problem.

The line was turned on Wednesday and municipal water records show there are 500,000 gallons of water unaccounted for – and it's not bubbling up through the streets, Schaefer said.

He said anytime would have been a bad time to lose the dock, but at this time of year, when the port city is gearing up for the arrival of the tourist season, it's particularly bad.

There are seasonal workers making their way to Skagway, and the loss of the dock represents a significant gap in the regular movement of freight, Schaefer said.

The mayor said nobody knows for sure how long ferry service will be suspended.

"I do have high expectations we are going to solve it as soon as possible and the Alaska Marine Highway System is treating this very seriously,” he said. "They are working feverishly to look at all the options.”

The mayor said while they suspect the waterline may have had something to do with the failure, the engineers who were on the scene Thursday did not have the blueprints of the dock with them so were unable to say how everything fit together.

"It was pretty sensational to watch it,” Schaefer said, explaining he went to the ferry terminal after having been notified of the problem. "We actually watched it go under.”

The mayor said the deck of the dock was visible yesterday evening at low tide, though it will probably be under another three of four metres of water during high tide.

A private tugboat was tied to the ferry dock but was able to depart before the dock sank.

A local barge crane was brought in Thursday to retrieve a forklift that went down with the dock.

Oil booms have also been placed around the area to capture any potential contaminants, says a release from the Department of Transportation.

The department said ferry traffic to Haines will not be affected.

Highway travellers using the marine highway who are bound for Skagway will have to drive the additional 565 kilometres from Haines to Skagway.

With assistance from Skagway News reporter Katie Emmets.