Quote:
Originally Posted by Aquaria
where does the moment of uprightening end? 35°?
Sy AquariaÂ*
|
Uwe,
I would have got back to you sooner on this issue but I have just spent a bit more than a week in the UK going through yet another Safety at Sea and fire-fighting course. I have to renew my certificates every five years (SCTW requirement).
To your question, assuming a vessel, initially in a stable condition, is heeled by an external influence (waves) she will, just like a yacht, generate a righting lever. This is known as GZ. From the GZ curves for differing angles of heel and displacement,you will see that the ESTONIA would not reach the point of vanishing stability before she was heeled 55 - 65 degrees. Lack if initial stability was not a problem for the ESTONIA. In fact, from the curves, one can see that ESTONIA's maximum GZ was in the region of 1.1m. The righting force would then be 1.1 X Δ where delta = displacement. As her displacement was 11,000 tonnes in this instance the righting lever is an enrmous 12,100 tonne-metres.
The IMO Panel of Experts accepted the findings of the Estonia Commission, i.e. the ESTONIA sinking was a result of the visor locks failing and that the subsequent water ingress caused a loss of stability resulting in the ship becoming unstable and sinking. Why does water ingress cause a lack of stability? Well, it is the free-surface effect of water. This you can easily test yourself. Take a round tray with a high edge (the type used in pubs) and place a tumbler of water on the tray. You can now support the tray from underneath with only one hand. Balancing it is not difficult. Now, lift the glass off and pour the water onto the tray and see what is does for the balancing act!
Certainly, the loss of the ESTONIA and her 852 passengers and crew in 1994 resulted in a host of new and amended rules and regulations regarding passenger ship safety but the fundamental fact remains that ferries have one or more continuous car decks. This space, if flooded, will result in a loss of buoyancy but will, in all probability, before sufficient buoyancy is lost to sink the vessel cause such a loss of stability that the vessel will capsize.
Judging from the reaction to the loss of the ESTONIA one would imagine that this was the first time a ferry sank as a result of water ingress on the car deck. This is not so. On the 6th March 1987 the Roll on/Roll off passenger and freight ferry HERALD OF FREE ENTERPRISE sailed from the inner harbour at Zeebrugge. The ship was manned by a crew of 80. Approximately 459 passengers had embarked for the voyage to Dover, which was expected to be completed without incident in the prevailing good weather. There was a light easterly breeze and very little sea or swell. The ship passed the outer mole at 18.24 and capsized about four minutes later. During the final moments the HERALD OF FREE ENTERPRISE turned rapidly to starboard and was prevented from sinking totally due to her port side taking the ground in shallow water. The HERALD OF FREE ENTERPRISE came to rest with her starboard side above the surface. Water rapidly filled the ship below the surface level resulting in the loss of not less than 150 passengers and 38 members of the crew.
The sinking of the HERALD OF FREE ENTERPRISE did not have the same impact as the sinking of the ESTONIA, probably because it was attributed to human error. The ship left the quay with her bow door open and took water on the car deck before the door could be closed. However, even this incident was not the first time a vessel had been lost due to water ingress on a car deck.
In 1968 the New Zealand ship WAHINE struck a rock when entering Wellington harbour. At 06:40 on Good Friday she struck Barrett's Reef. The WAHINE was the second ship to bear the name and had a gross tonnage of 8,948 tons. She was 488 feet (149m) long and, as such, one of the largest ferries in the world.
The WAHINE did not sink immediately but remained afloat for several hours until 14:30 when water ingress on the two-tier car deck caused the ship to capsize in 38 feet of water resulting in 51 people losing their lives; 44 passengers, six crew members and one stowaway.
I wonder why, more than 40 years after the loss of the WAHINE, ferries are still being built with continuous car decks? Of course, the answer is that loading and discharging such a vessel is simple and quick but should bean-counters be dictating how ships should be built or should that be left to professional seamen and naval architects?
Of course, much has been done to improve safety at sea; not least regarding the prevention of fires but these still happen. As an example, the Bahamas registered cruise ship STAR PRINCESS caught fire. The official report on the fire, published by the British Marine Accident Investigation Branch (MAI
, placed the blame on an unknown smoker whose cigarette ignited plastic partitions and furniture on one of the stateroom balconies surrounding the exterior of the ship. In fact, the balconies themselves, being constructed of aluminium, also caught fire. While room sprinklers kept the blaze from spreading to the interior, choking black smoke from the burning plastic blocked inboard escape routes. One person died in the incident and a further 11 were injured.
For further examples of fires on passenger ships we need look no further than Carnival Cruise Lines.
One of the most publicised incidents involved their ship ECSTACY which,in 1998, caught fire shortly after leaving her berth in Miami. As the ship had not left the port area there were capable of fire-fighting resources nearby. Had the fire had occurred a little later the outcome could have been very different.
The next year, another Carnival cruise ship, the TROPICALE, caught fire and the ship was adrift in the Gulf of Mexico with 1,700 passengers and crew members for almost two days after the fire disabled the engines.
In fact, the TROPICALE’s problems can be traced back to 1982 when a fire broke out during her inaugural cruise. The ECSTACY had also caught on fire earlier, in 1996.
Carnival has had more than its share of fires, with the Carnival celebration also burning in 1995.
The fire incident which I know best, having been called to the scene, was that of the SCANDINAVIAN STAR, also Bahamas registered.
The SCANDINAVIAN STAR was built in France in 1971 as a combined passenger ship and ferry for cars and trailers. Not being a requirement at the time, the ship generally was not fitted with either an automatic fire detection system or an automatic fire fighting system, although some spaces, such as the engine room, were fitted with this.
The ship had previously been operating out of Miami on short cruises but was purchased in March 1990 by the V R Dano Group to replace the HOLGER DANSKE on the run between Frederikshaven in Denmark and Oslo, Norway. The ship was quickly brought into service by the new owners, making its first run on the new service on 1 April. Only nine original members of the crew remained with the ship and they comprised mainly engineering crew including the chief engineer. The rest of the crew were either previous members of the crew of HOLGER DANSKE, consisting of deck officers and catering officers, or they were recruited new to the ship. This latter group were mainly "hotel staff' of Portuguese nationality.
The SCANDINAVIAN STAR came, as previously mentioned, into service on the new run on 1 April. It appears to have operated without incident until the tragic voyage on 6 April. The ship left Oslo at 21.45 that day under the command of Captain Hugo Larsen and with a crew of 99 and 383 passengers.
Between 01.45 and 02.00 on 7 April, a small fire was discovered in a pile of bed clothes on the port side of Deck 4. This fire was quickly extinguished. However, a little after 02.00, a second fire started in the aft section of the starboard corridor of Deck 3. The fire was not extinguished quickly and at 02.24 hours the ship sent a Mayday message giving an incorrect position, placing the vessel in Norwegian MRCCs sphere of responsibility. The maritime rescue co-ordinating centre in Norway therefore commenced to lead the rescue work. The correct position turned out to be in Swedish waters, 11 nautical miles west of Väderöarna.
From the Norwegian MRCC, Tjøme radio, an immediate alarm was sent out that assistance was needed. During the first half-hour three helicopters and 12 Swedish coastguard vessels, pilot-boats and search and rescue units, and three Norwegian helicopters, coastguard vessels and motor torpedo boats were sent out. From Denmark, several helicopters were sent.
At 03.20, the master of the SCANDINAVIAN STAR decided that it was not possible to extinguish the fire and the decision was taken to abandon ship. The master and his crew proceeded to evacuate the ship but did not ensure that all passengers had left before doing so themselves. Many passengers were still onboard the burning ship after it was towed to harbour.
At 11.55 the ship was taken under tow to the port of Lysekil in Sweden where she arrived at 21.17. At this time there was a small amount of smoke coming from the ship and externally there appeared little evidence of a major fire. However, during the night, whilst the fire brigade was trying to extinguish the fire, the fire developed and spread significantly causing extensive damage to most decks.
The fire was eventually extinguished on Sunday 8 April. During the following week, the emergency services were employed in removing the bodies from the ship. It was eventually found that 158 people had died in the tragedy; 156 passengers and two crew.
One would immagine that the consequences for the ship owner and master of the SCANDINAVIAN STAR would have been very severe. Not so. Three men were sentenced by a Danish court to brief jail terms in connection with the fire. The Copenhagen maritime court sentenced Norwegian Capt. Hugo Larsen to 60 days in jail; Danish shipowner Henrik Johansen and former shipping line director Ole Hansen received 40-day sentences. All three were found guilty of charges of being responsible for inadequate security arrangements aboard the SCANDINAVIAN STAR.
Anyone having read this far will by now, I am sure, be of the opinion that ships are not as safe as they should be - in fact, far from it and will check the positions of their lifebelts, muster stations and emergency exits before sailing on a ferry in the future.
Aye // Stephen
Linear Mode
