Viking Sky, the cruise ship which lost power and radioed a Mayday signal at the weekend, was today at the port of Molde in Norway – its 800 remaining passengers and crew safe and sound.

An investigation is now underway with maritime investigators in Norway, Britain and the United States looking into why all four engines on board the Viking Sky cruise ship failed while crossing a stormy stretch of Norway’s western coast.

Investigators also want to know why the captain decided to venture into a storm that had been forecast for days.

Some 430 passengers had to be taken off the ship one-by-one on rescue helicopters as the vessel, which lost power in its engines and was said to have been dangerously close to rocks, rode at anchor in huge seas and high winds.

Australians, British and American passengers were on board.  There were injuries, though Viking Cruises said in a statement none were life threatening. Local reports said 20 were taken to hospital.

Viking Cruises founder Torstein Hagen was on shore to meet some passengers from the rescue helicopter.

Mr Hagen said: “They have had a shocking experience.  Most of the passengers are senior citizens…imagine what it’s like to hang there on that wire. It must have been terrible – but they seem to have handled it well.”

Viking Sky lost power en route from Tromso to Stavanger  in a storm.

The crew managed to get one engine started to stabilise the ship.  On Sunday, as tug board stood by, they restarted two more, allowing the ship to slowly make its way to Molde, two kilometres away.

Through Saturday, five helicopters braved high winds to pluck sometimes elderly passengers from the deck of the Viking Sky.  Rescue vessels found the seas too high to risk docking with the ship, and were turned back.

See footage of the rescue here.

Footage from inside the ship showed the passengers in life jackets waiting to leave the ship, as furniture was thrown from one side of the vessel to the other.

Fisherman Jan Erik Fiskerstrand, whose boat was one of the first to come to help Viking Sky, told Aftenposten newspaper, “it was just minutes before this could have gone really wrong”.

The ship could have hit the rocks “if they had not started the engine and fastened the anchor” he added.

The authorities decided to launch airlifts rather than leave people on board and hundreds were hoisted to safety.

The BBC quoted Derek Browne from Manchester, who waited 10 hours for rescue, saying saying: “It was a very scary event.”

There was praise for the crew, who could be seen in video footage helping passengers to safety.

Lara from Birmingham in the UK, said “the crew were magnificent and have kept the remaining passengers safe, warm and fed”.

The company said “throughout all of this, our first priority was for the safety and wellbeing of our passengers and our crew”.

Engine failures are rare, and considering the huge increase in cruise ship journeys in the past decade, the industry has an enviable safety record.

The BBC quoted Trevor English, a technical author based in Texas who has written about the workings of cruise ships, who said: “It’s important we understand that the engineering of these ships are held to high standards.”

He said the Viking Sky had four engines – but it was possible for a component to stop all four, causing a complete power failure.

“What makes this event unique is the storms. In many cases, if engines are lost, they can be restored quickly with no issue.

“While one engine on the Viking Sky was soon restored, the storms made the lack of propulsion especially dire,” he said.

The maritime authorities and cruise line will be investigating the cause.