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Safe abandoning of ships, Improvement of current Life Saving Appliances Systems (SAFECRAFTS)

Final Report Summary - SAFECRAFTS (Safe abandoning of ships, Improvement of current Life Saving Appliances Systems)

SAFECRAFTS was an EU sponsored research and development project, concerned with evacuation systems on passenger ships. The two main reasons to reconsider ship evacuation systems are:
1. costs associated with ship evacuation systems;
2. the increasing size of cruiser passenger ships.

Costs of life saving equipment are frustrating, because it is always a pity to spend money on something you hope never to use. Ships increase in size over the years. Over the last century the length of passenger ships has increased by about 100 metres. The number of passengers has increased from 3 000 to 5 600. Together with the crew, ships may have a complement of up to 8 000 people. Although the ships obviously become bigger, their length does not increase to same ratio as the number of complement. As a consequence there is a lack of ship length to stow enough conventional life boats.

The SAFECRAFTS project was initiated with two objectives:
1. develop an assessment method for evaluating the performance of life saving appliances, which can cope with systems of very different concept;
2. generate two viable novel concepts.
Because of the requirement that systems bases on very different concepts should be assessed and compared with each other, the only viable approach was to take the humans to be evacuated as a basis for the assessment method.

One of the main challenges -and objective of this project- is to find a way to asses ship evacuation systems. This way is paved by identifying a parameter which quantifies the performance of ship evacuation systems. In order to be able to compare systems, the parameter should be system non specific. This can be achieved by understanding that the only factor the systems have in common is the human factor. Whatever an evacuation system looks like, it always has to deal with humans which have to be evacuated (evacuees). So in the end the only thing that matters is the well being of these humans. Well being can be quantified with a parameter which we have called the Human health status (HHS). This parameter is a four element vector specifying the human health. Each element gives the fraction of humans in each particular health status; the sum of the fractions in each of the 4 elements is always 1.0.

The health status elements are:
- good health, which means that people in this element are able to help themselves and assist others;
- moderate injury, implying that that people can still help themselves, but are not able anymore to assist others;
- severe injury which means people need help from others; and finally
- deceased where one does not require help anymore, but still there is the requirement to be taken ashore for final honours.

The fraction of humans in a particular status changes during the evacuation. An evacuation is considered as a number of obstacles which need to be negotiated by the evacuees. A sub-script can used to each HHS element which then denotes the number of obstacles negotiated. While passing an obstacle a part of the evacuees may get injured this 'degrades' them into a lower health status.

The vulnerability of humans -from a mechanical point of view- is an area where knowledge is reasonably well developed. In most cases, hardware behaviour during evacuation can be predicted through simulation. For validation purposes, tests in model basins are executed.

In spite of valuable information in literature, still many things are uncertain, therefore, tests are required with human subjects. For ethical reasons, these tests need to be done with volunteers, which is a disadvantage, since there is a self selecting mechanism. Yet, it is already better to have members of general public rather than people from nautical academies or the military. The mobility of evacuees has also been tested with a temporary facility. Volunteers were asked to slide down a chute into a life raft, to board a life boat, and to climb a rope ladder from a life boat or a raft to a 'rescue deck'. Tests were done without 'ship motions' and with 'ship motions'. Ship motions were emulated up to 10 degrees roll at a period of 16 seconds. During the tests, about 350 persons of varying age categories up to the age of 67 were 'processed for evacuation'. During chute evacuation there was only one refusal. It was interesting to note that the mobility of the evacuees was not so much influenced by the roll motion. From literature and tests with volunteers, it has proven possible to determine more or less a relation between motion levels and both human vulnerability and human mobility.

The other goal of the project was to generate two novel concepts for ship evacuation. Out of many ideas, two most promising concepts were selected. These concepts have been further developed.

One concept, called the Self propelled survival craft (SPSC), consists of multiple modules. These modules are stored at or near the centre line, in the aft of the mother ship. The modules are ejected over the stern, and slide along a ramp towards the water. The SPSC concept requires an amount of space similar to conventional boats, however, the space is now located inside the ship, which is less valuable from an operational commercial point of view. Deck space, required for conventional life boats, is the most valuable space in the ship. A slide ramp, as a launching mechanism, is considered less vulnerable, compared to a davit based launching system, especially in terms of control, complexity of the mechanics and maintenance.

The other concept is a life raft with partially rigid sides. This concept is called Hard sided life raft (HASLIR). The rigid sides contain propulsion, by means of small diesel engines or electric motors propelling thrusters. Effectively, thus a self propelled life raft is created. The HASLIR is still located at the 'boat' deck; however, the space required for storage is substantially smaller than the space required for life boats. Moreover, unlike lifeboats, only one deck level is affected for storage. Also the launching mechanism is very simple because of the HASLIRS low weight, a simple stores crane will be sufficient.

Both concepts would typically carry about 400 persons per module. In order to assess the feasibility of both novel concepts, prototypes were built. The size of the prototypes was reduced. For the SPSC, the prototype was scaled 1:2 and for the HASLIR the scale was 1:3.

The basic findings of the project are that the concept of equivalent safety actually works. In case of the HASLIR, the modules take substantially less space than conventional boats. This implies that the mother ship can increase in size because the storage space problem for evacuation systems is resolved. This is very important benefit for passenger ships, since deck space is the most valuable space there is on board. Money is also saved in this case since the HASLIR is relatively cheap. In case of the SPSC, the modules as well as the launching system are in a range of expenses similar to boats. Nevertheless, the SPSC doesn't require expensive deck space. This is a very valuable advantage. Also, the evacuation and launching system is very 'customer friendly'. Moreover the system is not normally exposed to the weather which reduced maintenance costs considerably.

The SAFECRAFTS project has managed to produce an assessment method which can be used to compare the performance of novel concepts with existing ship evacuation systems.

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