As we approach the 100th anniversary of the sinking of the Titanic this coming April, passengership safety remains an important issue.

Between 1990 and 2000, the cruise market increased by 60% and ship size grew to vessels capable of carrying well over 3,600 passengers.

Naval architects have devoted attention to methods of achieving rapid and safe evacuation, particularly access to lifeboats located at various parts of the passengership's superstructure.

Chutes or slides are now available for passengers to enter lifeboats already in the water, either directly into the lifeboat, or by means of a transfer platform.

These systems are designed to be effective in unfavourable weather conditions, or when the ship has heeled over. It is, or should be, understood that passengers on board a cruiseship may not be nimble, and perhaps may be partly handicapped. This affects the design and stowage of the lifeboats.

The loss of Titanic in April 1912 began a revolution in passengership safety that has continued to the present time.

Although an international conference was held in 1914, it was not until 1932 that an international convention for the safety of life at sea was agreed upon by major maritime nations. This convention has been reviewed repeatedly over the years, in the light of sometimes painful experience.

One of the biggest problems is philosophical: the great cruiseships of today are perceived by the public as large floating hotels or casinos. Significantly, modern cruiseship passengers are generally referred by liner companies as "guests".

Nevertheless, a ship at sea, even one close to shore, is exposed to an array of hazards that cannot always be avoided. How a ship, including a large passengership, can survive such risk depends on a number of factors.

Most worrying about modern passenger vessels is the very large number of human beings on board, a factor that presents previously unprecedented logistical problems if anything goes wrong. Many observers have asked whether numbers of elderly or partly handicapped passengers can endure the stresses of a speedy emergency evacuation from a vessel that may be more than five storeys high.

In recent years, as passenger vessels have grown larger and larger, these issues have become more obvious.

Although a passengership casualty, when one occurs, is often referred to as "unprecedented", the question of how to safely evacuate a ship carrying thousands of people is not new.

Naval architects have raised concerns regarding the designs of passengerships repeatedly in recent years, even as computer simulations, modern materials and technology have improved the design process. To begin with, there is no such thing as an unsinkable ship, a lesson learned repeatedly over the centuries.

A continuing cause for concern is the effect of fire, or more likely loss of oxygen, within an enclosed environment. This problem of course applies in a sealed building as much as a ship.

However, because of the common presence of "atriums" within many modern passenger vessels, the impact of fire or heat, and loss of oxygen, within a limited area could be dangerously enhanced, and with it, the risk of asphyxiation.

Giant cruiseships may have as many as 12 decks, and a large number of stairs, elevators and other exits, all of which, however well indicated, may be bewildering or at least unfamiliar to passengers.

The design of the giant supership does not permit old-fashioned muster lifeboat drills, familiar to film-goers of a certain age, in which passengers were sent to boat stations shortly after a voyage began. Today, such drills are often merely simulations, in which passengers are shown a video, or other form of demonstration.

The logistical problems of evacuating a giant cruiseship, carrying thousands of passengers and crew, are in urgent need of reassessment.

Among the unresolved or unpredictable variables is what happens if a significant number of lifeboats are submerged when a passengership develops a rapid and extreme list. Pictures of Costa Concordia with all of its starboard lifeboats under water illustrate that this could be a problem.

Just as in the case of Titanic , the question is not simply whether there are enough lifeboats or rafts, but whether passengers will have a reasonable amount of time to gain safe access to them.

If a list develops quickly, or if weather is bad, the ship's design must permit every possible means to safely evacuate passengers and crew.

A well-trained crew, specially trained to handle the evacuation of a large number of passengers and staff, is indispensable.

Clay Maitland is a Fouding Chairman of NAMEPA and Managing Partner of International Registries

Above article is an edited version of Clay's interview regarding the Costa Concordia accident.