Over-reliance on electronic navigation systems and a failure of judgment by the captain are seen as possible reasons for one of the worst cruise liner disasters of all time, maritime specialists say.

Industry experts say modern passenger ships such as the Costa Concordia, that ran aground off Italy's west coast at the weekend, are equipped with state of the art global positioning systems and collision avoidance radar tracking facilities. Nevertheless, the human dimension is still vital.

All these gizmos are aids to navigation and it does not absolve you, as master, from taking responsibility for exercising good seamanship which is constant monitoring of your position accurately and making reference to all available material including printed charts and the local knowledge of the area, said John Dalby, chief executive with specialists Marine Risk Management.

At all times the master is responsible for the safe navigation of a ship, and he ultimately bears the risk responsibility here.

The operator of 114,500-tonne Costa Concordia said the captain's actions had caused the tragedy in which at least six people died.

Dalby said there were also questions about whether there were enough qualified crew with maritime experience on board, rather than staff whose role was in passenger hospitality.

In a situation where you are in confined waters, things can happen very, very quickly; faster than a GPS can refresh or be referred to, he said.

Pier Luigi Foschi, chairman and chief executive of Costa Crociere, which operates the Costa Concordia said on Monday the crew responded adequately given the circumstances in line with the training and instruction they have received.

Foschi said the ship had deviated from the correct route when it hit rocks near the coast, tearing a large hole in the hull, and that the captain had contravened company safety procedures.

The only thing I can repeat is that was not the ordinary route that the ship was taking at the time, he said.

The captain denies being too close to the coast and says the rock he hit was not marked on charts.

SAFETY AT SEA

Other maritime experts said a combination of human and technical errors were likely to have contributed.

An error chain is where several things have gone wrong, said Len Holder, former master of the Honourable Company of Master Mariners industry association.

Looking at the Herald of Free Enterprise, several things went wrong, none of which should have caused the accident but when they all came up together that is where the problems occurred, he said referring to a British car ferry disaster in which 193 people were killed.

U.N. shipping agency the International Maritime Organization (IMO) said if necessary it would re-examine safety regulations for large cruise liners pending the outcome of investigations.

Cruise ship safety measures are regulated by IMO conventions.

It is important to recognise that the last century has seen an astonishing growth in legislation on the safety of shipping, a senior ship industry source said.

Marine accidents are now rare events when the thousands of voyages undertaken annually in often appalling weather are taken into account. Certainly no more regulation is required but a focus on application and compliance may be something that the IMO will consider.

IMO Secretary-General Koji Sekimizu said the outcome of the investigations should not be pre-judged, adding that the agency should not take the accident lightly, adding that the causes of the incident were still not established.

We should seriously consider the lessons to be learnt and, if necessary, re-examine the regulations on the safety of large passenger ships in the light of the findings of the casualty investigation, he said on Monday.

Others said the disaster could encourage more rigorous training of crews.

In the immediate future aftermath if there is a higher emphasis on the inspection of cruise ships, that maybe focused towards the training and qualifications of the navigating crew and the crew that is assisting with emergency responses in terms of helping passengers, said Ted Thompson, with the industry Cruise Lines International Association (CLIA).

Some maritime specialists say the growing size of cruise liners has posed risks in the event of a sinking.

The problem with the big ones tends to be getting people off safely if there is an incident, said Holder, who is also chairman of maritime training company Videotel.

Industry officials say size was not an issue.

Different ships are built for different markets, different routes but every cruise ship is built to operate or is certified to operate around the globe, said Robert Ashdown, technical, environment and operations director for the European Cruise Council, the umbrella group for cruise companies.

These ships routinely face the worst that nature can throw at them, whether it's the Bay of Biscay in December or whether it's a Caribbean tropical storm or the high seas of the Antarctic ocean. These ships are stable in those conditions and they are safe.

CLIA's Thompson said new cruise liners were fitted with propeller systems that enabled more manoeuvrability.

To actually turn a ship .. is much more quickly done than in the past, he said. This is such a one-off event, passengers can and should feel safe cruising on modern cruise ships.

(Additional reporting by Paul Sandle and Drazen Jorgic)