New life for lifeboats

IN AN environment where ships and passenger numbers are growing in size, the idea of the ship as its own best lifeboat has been growing in importance.
That said, the fact that passengers and crew might need to evacuate a ship at sea cannot be ignored.
While the commitment to having lifeboats on ships remains strong, so does the willingness to look at new concepts.
Last week, the International Maritime Organization (IMO) was presented with just that – an innovative new approach to the safe abandonment of ships at sea.
The Safecrafts project is the fruit of six years’ work spearheaded by the Netherlands Research Organisation (TNO) with participation from a wide range of industry bodies.
TNO undertook the Safecrafts project with a commitment to the European Commission that it would develop an assessment methodology for ship evacuation systems.
In addition, TNO committed to coming up with two novel concepts on evacuation.
With recent changes to Safety of Life at Sea Convention that encourage the alternative design of lifesaving appliances, the European Union was prepared to provide funding through Framework Project 6 for the Safecrafts project.
The project has brought together a group of 18 partners, which include academics, research institutions, shipowners, yards and classification societies.
The mix of disciplines ensured that there were operational people present, who would have to live with the results of the project, as well as lifeboat designers and builders to ensure that the project was possible to achieve. TNO acted in a moderating role.
One key feature of the current research is that Solas already provides for alternative, innovative solutions to the issue of ship evacuation provided those solutions demonstrate equivalence with regulatory standards.
There were two main issues to be considered when approaching a new assessment of ship evacuation systems, according to Alex Vredeveldt, a senior scientist at TNO’s Centre for Mechanical and Maritime Structures.
Firstly, for owners there was the issue of paying the cost of life-saving equipment that they hoped would never have to be used, Mr Vredeveldt said.
Secondly, as the number of passengers and crew on ships has increased dramatically over the years, space was at a premium, particularly as far as stowing lifeboats was concerned.
With ship sizes increasing, alternatives needed to be considered and unlike 10 years ago regulators are prepared to consider these provided equivalence is demonstrated.
This is outlined in Chapter 1, Part A, Regulation 5 and Chapter III, Part C, regulation 38 of Solas.
Guidelines for alternative design and arrangements were also outlined in the International Maritime Organization circular MSC.1/Circ. 1212. Concepts such as Goal Based Standards and Formal Safety Assessment are encouraged within the IMO, Mr Vredeveldt said.
Evacuation
Designers and scientists are encouraged to identify novel concepts and provide technical evidence demonstrating their safety-level equivalence, he said.
One of the most challenging aspects of the Safecrafts project was to come up with a way of assessing ship evacuation systems and how to “give marks for getting it right”, Mr Vredeveldt said.
As he pointed out, the only factor the systems have in common is the human factor.
“The whole idea of evacuation is to make sure people are taken off the ship and taken to a place of safety,” he said.
“It is important that they are in good health, although some will not be initially and may get worse.”
A parameter called the human health status was created to measure the wellbeing of passengers, Mr Vredeveldt said.
This comprised of four elements: those in good health, who were able to help themselves and others; those with moderate injuries, who could help themselves but not others; those with severe injuries, who needed help from others; and those who were dead and whose bodies needed to be recovered.
One key element was to consider human behaviour and how people perform in casualty situations, taking into account human vulnerability and mobility.
Even those in good health might not be able to, for example, climb a rope if necessary.
The evacuation process meant that passengers and crew would have to negotiate a series of obstacles, for example, boarding the lifeboat or sliding down an escape chute, launching the craft, survival in a craft at sea and boarding the rescue ship.
People might be at risk of toppling off a seat in the lifeboat or prone to seasickness, which might lead to a deterioration in their condition as they became dehydrated.
On arriving at the rescue ship, passengers might be required to climb a rope ladder, for example. As they negotiated successive obstacles, their health status might change, Mr Vredeveldt said.
The methodology aims to “predict how many will move from one health status to another as they negotiate the next obstacle”, he added. This could be calculated mathematically.
Conditions of the evacuation have also been considered including sea state, the degree of list and trim of the ship and the heading angle, Mr Vredeveldt said.
The assessment parameter assumes that the passengers would be at sea for 24 hours and five scenarios are included that cater for sea states going up to Force 6.
List calculations go up to 20% and trim calculations to 10%, he said.
This was deemed sufficient as 10% of trim by the stern would mean the casualty’s poop deck would be under water.
List and trim values are taken from the IMO’s lifesaving appliances code, Mr Vredeveldt said.
The other parameter that influences the assessment method is the probability of failure of subsystems, like davits or breaking mechanisms. Usually, such probabilities are established from a failure mode and effect analysis.
“Fortunately there are insufficient accidents to produce any meaningful statistics, therefore the FMEA is the only way to establish probabilities,” he said.
In most cases, hardware behaviour during evacuation can be predicted through simulation.
As far as human performance from the mechanical point of view is concerned, there is a wide range of knowledge available on the impact of vertical accelerations or impact during launching to assess the effects on the human body.
Although tests on real people present ethical problems, theoretical analysis can be used to calculate the motions of a lifeboat, although liferafts present more difficulties because they are not flexible structures, Mr Vredeveldt said.
The other part of the TNO project was to come up with two novel concepts for life-saving appliances.
One concept for a self-propelled survival craft came out of the Safedor project, which was presented at IMO last month following four years of work. The modules, designed by Fassmer, would be stored inside the ship, and launched from the stern of the ship down a ramp.
Clearly, if the ship had reached the critical 10% trim by the stern, the launch would not work as the stern would be submerged.
The other novel concept under development is a hard-sided liferaft, which is bigger than the conventional ones and uses the liferaft’s outer casing to reinforce the raft’s sides.
This means it would be possible to attach outboard engines to the liferaft, making it less dependent on being towed by a tender. A prototype, the Haslir, has been designed by Viking.
Development of new concepts obviously puts pressure on engineers and designers but “designers should be responsible for safety, not regulators”, he said.