When subjected to the vagaries of nature, technical miscalculation and bad luck mixed with human frailty, it’s a truism that no ship is unsinkable.

Ever bigger ships are being built. Some gigantic liners are now of more than 220,000 gross tons and carry 6400 souls and every conceivable safety device.

The improvements in technology built into today’s ships and advances in navigation and communication, ensure that everything humanly possible is done to prevent disaster, and if calamity strikes, to effect a speedy rescue.

But it is this human factor that consistently has been found wanting. 

The tale of the so-called ‘unsinkable’ RMS Titanic, which struck an iceberg and sunk on April 15, 1912 with the loss of 1,517 lives, is a case in point. Although the technology that went into the Titanic is some 100 years old, there are still lessons to be learned about the human factor.

Unsinkable Titanic, directed by Patrick Reams, not only takes us through the well-known litany of miscalculations and blunders, including unexpected flooding over five bulkheads and the owner’s reduction of 48 lifeboats to 16, but it also explores another, newer reason for the liner sinking so rapidly.

Scientist and author, Jennifer Hooper McCarty, discovered flaws with some of the rivets used in fixing the plates of the Titanic. The shipbuilders used both steel and wrought iron rivets. Under an electron-microscope, McCarty found large slag impurities embedded in the structure of the wrought iron rivets.

"It created a weakness in the heads of the rivets. During the collision that night those weak rivets couldn’t withstand the force and their heads popped. As a result of them those rivets next to them had to carry more load and those heads popped and so you get an unzipping of the seam along the starboard side."

Human nature played a major part, the production insists. The builders of the Titanic allegedly didn’t order the purest grade of wrought iron, but settled for a lower grade with impurities.

"If you have good wrought iron," says McCarty, "you don’t have that weakness... the rivet will fail, but it’s going to last a little longer and 1,500 people – their lives would have been saved. And then a boat could have gotten there and rescued people before the ship was doomed."

The Titanic’s builders, Harland and Wolff, deny McCarty’s rivets theory.

Disbelieving Australian tourists were among the 1,195 passengers of the MV Sea Diamond which hit a reef in calm waters inside the caldera of the fabled Greek island of Santorini on April 5, 2007.

Some were huddled in lifeboats that had to be chopped free from davits only to crash many decks to the water below. That evening the passenger ship rolled over and sank. A Frenchman and his daughter were lost.

An investigation appears to have cleared the shipowner and master, according to shipping experts writing in Lloyd’s List. Court appointed experts reportedly agree that the Sea Diamond hit a reef 130 metres from shore when it is marked on charts as being only 57 metres from shore.

Could another passenger ship sink after hitting an iceberg in view of the lessons from the Titanic? Surely not?

Well, in fact, one passenger ship did go down only seven months after the 2007 sinking off Santorini. The small cruise ship MS Explorer with 154 passengers and crew aboard struck submerged ice in Antarctica near the South Shetland Islands.

A nearby Norwegian cruise ship plucked the survivors from their lifeboats.

Lawyers will continue to debate responsibility for sinkings at sea, but so often the human factor is there in disasters and - as every mariner knows - there still is no room whatsoever for complacency.