The Stanley Gray Lecture: 11 June 2002 The Derbyshire and its Message _________________________________ In the history of British Shipping there have been many tragedies and many mysteries but few have captured the public’s concern as much as that of the Derbyshire. How could the biggest British ship ever lost at sea simply have disappeared almost without trace? Here was a vessel so large that, if stood on end, it would be substantially taller than Canary Wharf. It was only 4 years old, British-built and entirely compliant with LRS class rules and requirements. Yet, having been overtaken by a SW Pacific typhoon, of not unusual intensity, it was lost with all on board without so much as a distress signal. Not surprisingly there was a very strong public feeling that this disaster had to be explained. And not surprisingly there was a feeling that if such a vessel could be lost there must be something wrong with its design. If it happened once, it could happen again. It is perhaps no exaggeration to say that when in September 1980 the terrible truth of the loss emerged, nobody could have believed that one event would over the next twenty-two years be making a major contribution to the techniques of underwater investigation of losses, to our knowledge of how such vessels respond to violent sea conditions and to how experimental investigation can be utilised to test the adequacy of design assumptions by ascertaining the magnitude of risk of loss. We have also learned a little bit about the way in which enquiries can be conducted so as to produce meaningful results within a reasonable time and at reasonable expense and, perhaps most importantly of all, so as to engender an on-going remedial process aimed at achieving a solution to the problem represented by the loss. Let me start with the whole question of ship design. It is hardly surprising that for many years it was believed that by for the most likely explanation for the loss of the Derbyshire was that its hull had split open at frame 65 which was regarded as a highly stress-vulnerable location just forward of the superstructure and aft of the ninth and aftermost hold. The assumption was that there was insufficient structural strength in way of frame 65 because of the design features or because the builders had not worked sufficiently accurately to the design or both. The first public investigation into the loss, conducted by Gerald Darling QC as Wreak Commissioner, specifically addressed the question whether the design in way of frame 65 was satisfactory. The issue was whether, having regard to the design drawings and evidence of construction, there was such discontinuity between the topside tank vertical side which stopped at the forward side of the transverse bulkhead at frame 65 and the longitudinal engine room bulkhead which started on the aft side of that bulkhead as to give rise to such an interruption in loading as to create significant risk of areas of high stress concentration which might cause the hull to split open. On the basis of the expert evidence of the relationship of design to relative stress loading the Wreck Commissioner concluded that there had been no causative design defect. The main reason was that the point of maximum location of bending moments would be well forward of Frame 65 so the hull was more likely to fail amidships than aft of No. 9 hold. In other words, it was likely to fail first at the point of highest stress concentration.
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On the other hand, he was quite unable to put forward any specific causative mechanism for the loss. This result was a matter of profound dissatisfaction to many – both to the families of those who had perished and to many who were concerned with the details of ship design. After all, had not the sister ship “Tyne Bridge” developed cracks in her deck in way of frame 65 in the course of a voyage across the North Sea in severe conditions in March 1982? And then there was the “Kowloon Bridge”, another sister ship, which in November 1986 developed a crack between No. 9 hatch and the pump room, in the course of a laden voyage from Canada to the UK. So serious was her condition – with the crack expanding – that she was obliged to put into Bantry Bay for temporary repairs – only to founder when her steering gear was crippled and she drifted on to rocks and sank, having broken her back in way of Frame 65. Indeed the Formal Investigation under Gerald Darling was appointed in December 1986 – already more than six years after the loss of the Derbyshire - largely because, following the experience of these sister ships, the Frame 65 junction was seen as presenting a highly suspicious design feature. It is worth remembering that at this stage flooding of the forepeak and bow compartments forward of No. 1 hold followed by loss of forward freeboard and consequential failure of the forward hatch covers due to hydrostatic loading was not then seen as a major contender to explain the loss. Indeed, the report concluded that although this was a possible cause of the loss, it was an improbable one. Although the Wreck Commissioner’s report, eventually completed in January 1989, excluded all the main suggested loss mechanisms as improbable or unlikely, it failed to reach any other conclusion as to the cause of the loss than that the vessel was overwhelmed by the typhoon, possibly after getting beam on to the wind and sea. Thus, the beam-on capsize scenario was implicitly put forward as the only real possibility. This conclusion was not entirely surprising, given the lack of factual evidence then available. Looking back, it is important not to lose sight of the fact that absolutely nothing was known of the damaged condition of the vessel or of the vessel’s attitude in the process of sinking or of the wreckage field on the seabed. Indeed, it was not then even known where on the sea bed the wreckage was located. Nothing was known because there was in the 1980s no sufficiently reliable technology for locating the wreckage and for exploring the sea bed wreckage field. That capability was not available until the early 1990s. However, it was an extremely expensive capability, heavily dependent on United States ROV technology. Unless highly accurate and well-defined photographic material could be obtained it would not be possible to conduct a meaningful investigation. At this point I have to pay tribute to two major contributors to the whole Derbyshire achievement – a word I use deliberately and to which I shall return later in this lecture. I refer first to the ITF. Without their financial support for the exploratory survey which in March 1994 first located the wreck 4200 metres below the surface of the Pacific, I am extremely doubtful whether investigation of this disaster would have been taken any further forward. Second, I refer to Lord Donaldson whom the Minister of Transport appointed the following year to assess what further steps could be taken to obtain evidence as to the cause of the loss, the cost of such steps, what benefit to ship safety could be secured if the cause of the loss were established and whether this would justify the likely costs.
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Lord Donaldson who had recently retired from the bench as Master of the Rolls and whom I have known for nearly 40 years has that instinctive commonsensical perception which, together with his formidable analytical expertise, made him the ideal choice to answer the question. His understanding of the capabilities of available technology and his appreciation of the implications that the additional evidence might have for future ship safety left him in no doubt that a full-scale underwater investigation should be conducted. Although some people in central government were distinctly sceptical of his conclusions, it was eventually decided to accept the and with partial financial assistance from the EU to proceed to the investigation. Once again it needs to be appreciated that, but for Lord Donaldson’s assessment, the whole Derbyshire exercise would have stopped in 1995. The technology used for the underwater survey, which took place in 1997 and 1998, was one of the most remarkable evidence retrieval operations ever conducted. It relied essentially on two key techniques: first the creation by the Argo III system, accurately positioned by means of acoustic navigation, of over 130,000 black and white still photographs of the wreckage, which made it possible to identify about 2500 separate items of wreckage by joining up the separate stills into a mosaic and so providing three-dimensional images; second the use of the Jason system to take video film of the wreckage, the camera being manoeuvred by communication from the towing vessel by way of a fibre optic steel umbilical. The US Government made a major contribution to the whole operation by making the equipment and personnel to operate it available. Following the survey there came the report of two out of the three technical assessors who had been on board the survey vessel: Robin Williams and Dr Remo Torchio, the third Prof Faulkner having resigned. That report had a dramatic effect and for two reasons. First it identified bow flooding as the most likely effective cause of the loss, that is to say bow-flooding followed by sequential failure of the forward hatch covers and consequential loss of forward freeboard. In other words, design and construction in way of frame 65 was not seen as a likely cause of the loss. Second, the finger of blame for bow flooding was pointed directly at the crew. It was said that the forepeak inspection hatchcover had been left unsecured or open. Although my report eventually rejected this suggestion, it is probably true to say that it is somewhat unlikely that, but for this allegation, there would ever have been a re-opening of the formal investigation. The intense political pressure for the re-investigation of the whole of the available evidence by the Derbyshire Families Association coupled with the personal commitment of the Deputy Prime Minister, John Prescott presents a remarkable example of how in a modern democracy public opinion can take forward scientific and technological achievement. Indeed, the whole history of the Derbyshire has been a story of pushing forward the limits of technological research and development. If we start from the underwater photography and video creation and travel through the events of the Re-opened Formal Investigation itself we find what I suggest is a remarkable development of technological and risk analysis expertise which I hope this lecture will serve to
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recognise. Although it is not possible to say of any of the many components which were assembled to produce the conclusions on cause of the loss and the dependent recommendations of the final report that, without each of them, the whole exercise would have been either impossible or very much less vulnerable, it is really the combination of all the components which gave those conclusions and recommendations their credibility and acceptability. Let me start with the series of model tank tests conducted by the Marin Research Institute at Wageningen in the Netherlands. The technique of tanking-testing to ascertain wave impact and loading is of course long established in this country. Years ago the Teddington navel research laboratory was at one stage internationally predominant in this field. But that remarkable establishment has long since fallen victim to the government accountants and research of this kind is now effectively confined in this country to the Ship Stability and Research Centre at Strathclyde University. It was upon that establishment that reliance was first placed to obtain an analysis of possible hydrostatic loading on the forward areas of the vessel in the sea conditions likely to have been experienced. However, those sea conditions had in turn been calculated without any assumptions as to multi-directional wave motions, which might have been experienced in the relevant West Pacific typhoon. Dr V J Cardone of Oceanweather Inc, an American specialist organisation in the field of oceanography and the hindcasting of weather and sea conditions, had recently developed computer methods of hindcasting the key factor of significant wave height which took into account the effects of multi-directional seas. It was obviously essential that his results should be incorporated into any modeltesting regime. This involved the replication in the testing tank of multi-directional seas – a facility not available at the Strathclyde laboratory. It was therefore decided to engage the services of Marin in whose model tank such conditions could be replicated. There then began a most remarkable research exercise. Not only did Marin make a vital contribution to the final report, but it has, since that report, been engaged in a research programme paid for by the UK Department of Transport and agreed with IACS (the International Association of Classification Societies) which has added enormously to what we know of both hydrostatic and hydrodynamic loading in violent seas. So the latest technological developments in the field of oceanography and hindcasting demanded, and were met by, new developments in model testing techniques. And eventually with remarkable results. It was reasonably clear from the outset that there were two keys to our understanding of the extent to which, if at all, the flooding of the bow spaces of the vessel had triggered the loss of the vessel. First, it was essential to know the rate of ingress of sea water into the bow spaces through possible points of ingress on the foredeck, such as ventilators which might have been damaged or destroyed prior to bow flooding, and it was important to have that information in the assumed sea conditions at different possible speeds of the vessel, namely zero, 2 and 4 knots. It is worth recognising at this point that the likely speed of the vessel through the water became an issue of great importance in the course of the Inquiry. The second key was the hydrostatic loading on the No.1 hatchcover. The vessel’s hatch cover strength requirement in force at the time when the vessel was designed and built, namely that derived from the International Load Line Convention 1966.
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Under that Convention bulk carriers were permitted to maintain the minimum freeboard of a dry cargo vessel reduced by 60% of the difference between the lower permissible tanker freeboard and the higher permissible dry cargo vessel freeboard, but subject to adequate internal flooding protection. The minimum strength of mild steel forward hatch covers was capable of loads of not less than 1.75 tonnes per sq metre. In terms of the Derbyshire’s hatchcovers this was equivalent to a collapse strength of 42 Kpa (kilo paschals). The vessel’s forward hatches were slightly, but only slightly above that strength. It is, however, important to appreciate that the Convention minimum hatchcover strength requirement necessarily involved certain assumptions about the likelihood of hydrostatic loading, in particular the assumption that the incidence of loading in excess of that level was likely never to occur or at worst to be exceptionally rare. Second, it involved the assumption that the prescribed freeboard would be maintained in the course of green water loading so that the minimum strength of the forward hatches need be calculated by reference to the incidence of loading likely to be experienced by the vessel only in an intact condition. That is to say with the watertight integrity of the bow and forward cargo spaces maintained. The Convention did not therefore specifically address the minimum strength of foredeck aperture fittings nor did it specifically deal with the problem of the loss of freeboard due to bow flooding. The work on the Derbyshire has taught us that these were very serious omissions. Dr Cardone had calculated that the significant wave height at the time and location of the vessel’s loss was 10.85 metres. His range of accuracy was 10 per cent (i.e. up to 11.94 metres). It was considered appropriate to look at the loading up to 12.5 m to take into account an extreme sea condition scenario. This represented a 15% increase of Dr Cardone’s significant wave height. The results eventually obtained in the Marin tests were, it has to be said, of fundamental importance to the whole conclusion of the Investigation. When the bow was not flooded, the loading on No.1 hatch cover was well below design collapse strength (42 Kpa) at zero speed and at 2 knots and only slightly above collapse strength at 4 knots with a significant wave height of 12.5 metres. However, it was when the bow was flooded and the forward freeboard had been reduced that the problems arose. The maximum measured impacts were all at or in excess of 42 Kpa, even at zero speed for a significant wave height of 10.85m. Indeed, at a significant wave height of 12.5 metres, 55.5 Kpa was recorded. That was well in excess of the collapse strength of the No.1 hatch covers on the Derbyshire. The Marin tests by their very nature could not be conclusive as to the likelihood of the forward hatch covers having been subjected to excessive loading. There were two main problems. Firstly, they had been conducted over periods far shorter than the period of exposure of the vessel to violent conditions. The vessel had been exposed to a period of significant wave heights of about 10 metres from 0800 on 9 September to 0500 on 10 September, some 21 hours, whereas the Marin tests had all been conducted over periods of 90 or 120 minutes. Secondly, they assumed that the whole of the bow space had been flooded and there was therefore no data on the likelihood of the occurrence of a wave of hatch-breaking force, if only part of the bow was flooded, such as the bosun’s store or the forward deep tank or both.
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Because of the prolonged exposure to severe sea conditions there was a possibility that, even if hatch-breaking impacts had not been recorded in the Marin tests, they might nonetheless have affected the vessel during the actual prolonged period of exposure. Further, the gradual filling of bow spaces and the consequent progressive loss of freeboard would obviously lead to a progressively increasing risk of exposure to a hatch-breaking wave over the relevant period of time. So there was a possibility of a changing exposure to risk over an extended period of time. Therefore in order to test the likelihood of the incidence of a hatch breaking impact it was necessary to extrapolate from the Marin results. In the course of the hearing an acute controversy arose between the experts as to the appropriate statistical methodology to be employed for this purpose. Since the results derived from the competing methodologies varied considerably I came to the conclusion that the only way of solving this problem was for me to appoint a sole expert in extreme value statistical extrapolation. And so at a very late stage Prof Jonathan Tawn of Lancaster University came on to the scene. He and Dr Heffernan of his department worked with amazing rapidity to produce the extrapolations, which became the vital link between the Marin data and the analytical exercise which I had to do to arrive at the conclusion. Naturally statistical extrapolation depends for its significance on the accuracy of the data introduced into the statistical analysis and the data in this case could not by its very nature be absolutely accurate, in particular the calculation of significant wave height and the measurements of water ingress rates and impacts by Marin. However, there can, in my view, be no real doubt that the combined exercise of hindcasting, model testing and the application by Prof Tawn of the Generalised Pareto statistical model to the basic date produced an entirely reliable analysis of the probabilities of hatch cover collapse. This is not the place for a detailed exposition of the results of that exercise. However, the following points are worth emphasising. Without prior bow flooding at a significant wave height of 10.85m and a speed of 1.5 or 2 knots there would be no risk of a hatch-breaking wave. It was only when the speed was increased to 4 knots that such a risk arose. Since the most likely speed of this vessel and similar vessels in such hearing seas would to have been safe unless the significant wave height were increased. And here begins the danger area. With an increase of only 10 per cent in the significant wave height, the risk of a hatch breaking wave was 1 per cent at 1.5 knots and 4 per cent at 2 knots. 4 per cent is by no means negligible in the context of risk of loss of life. However, if the wave height were increased by 15%, the 1.5 knot speed gave a risk of 2 per cent whereas at 2 knots the risk was in the range of 26% to 34%, a truly major risk. The overall effect of these results was to show that the risk of a hatch-breaking impact was highly sensitive to very small variations in forward freeboard and therefore to relatively limited water ingress. Thus at 1.5 knots, if the freeboard were reduced by 40 cm (equivalent to flooding the bosun’s store) there would be no chance of No.1 hatch collapse, whereas if it were reduced by 110 cm (equivalent to flooding the ballast tank through one larger orifice, the risk of hatch collapse would not only arise but would lie in the range 20% to 70%. If the vessel encountered a significant wave height at the top end of the accuracy range of Dr Cardone 11.94m) it was certain that there would be a hatch breaking wave
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when the bosun’s stores and ballast tank were flooded and a 1% to 10% risk of such a wave if the stores alone were flooded. At this point I would like to emphasise two considerations. First, this typhoon was not of exceptional strength in the Western Pacific. It could therefore be assumed that if a vessel of similar design to the Derbyshire was unlucky enough to encounter such a typhoon it would similarly be exposed to risks of a hatch breaking wave once its bow section was wholly or partly flooded. Secondly, once the No.1 hatch cover had collapsed the loss of freeboard would be so great that the No.2 hatch would be subjected to a much higher risk of hatch-breaking impact than the No.1 hatch had been and the sinking of the vessel would thus become inevitable. Indeed, it was calculated that No.1 hold would fill with water within 5 to 16.5 minutes after its hatch covers gave way and it is obviously extremely probable that by the time such filling was complete, the No.2 hatch would have collapsed. One is thus looking at an extremely rapid sequential flooding process and one which is not affected by the existence of a water-tight bulkhead between No.1 and 2 holds. If this were to happen in the likely circumstances that the loss of freeboard could not be detected from the bridge either because of darkness or because of the view of the forepeak from the bridge being obscured by waves and spray, there would be little or no chance to get the crew off the vessel before it sank. It follows that there are to be derived from this disaster two highly important areas for remedial action. First there is the need to require by international convention that bulk carriers have significantly increased strength in their forward hatch covers and in their bow aperture protection. Second there is the complementary need to provide for the effective monitoring of the water-tight integrity of the hatch covers and of the bow apertures. Let us first look at hatchcover strength. According to the unchallenged evidence of Dr Cardone, during the period 1971 to 1986 there were 77 tropical typhoons and in terms of wind speed Typhoon Orchid – that which hit the Derbyshire – ranked 34th. Of the 24 most severe typhoons in the North West Pacific the peak significant wave height ranged from 7.2m to 17.6m. In terms of significant wave height Orchid ranked 8th on the basis of a peak wave height of 12.6 m. Given that there can be up to a 10% accuracy variance, a wave height factor of 15m is probably the minimum sensible wave height reference for the development of a new minimum hatch strength regime. If one assumes that the peak significant wave height is 12.6m. The recurrence interval in the SW Pacific would be about once in a minimum of 5 years. For a 300m capesize bulk carrier, applying the Buckley Survivability Envelope, it would therefore seem safe to assume a sea condition of 15m significant wave height and a wave period of 14 seconds. My report concluded that the 1966 Convention was seriously defective in as much as it very substantially under-estimated the minimum forward hatchcover strength and in as much as the methodology of calculation was conceptually defective. Let me
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explain the latter. The Convention provides for the factoring into the calculation of minimum hatchcover strength of a safety factor in terms of a ratio of 4.25 ultimate tensile to maximum working stress which is roughly equivalent to a ratio of 2.5 between maximum design stress and yield stress for mild steel. And yet on the Derbyshire there was no material reserve strength – the collapse load being almost the same as the nominal pressure load to cause first yield. The 1966 Convention methodology may therefore omit any significant reserve strength and the so-called safety factor is therefore potentially illusory. One of my recommendations was therefore that not only should the minimum strength requirement of the forward hatch covers be calculated by reference to ultimate collapse strength but that it should be very substantially increased. The report does not contain a precise replacement formula nor does it identify precisely how deficient the Convention’s minimum requirement is. However, in the context of one of the most important recommendations which I shall come to in a moment, it seemed appropriate to introduce a suggested reference methodology which is that set out in Appendix 46 of the Report. What did become abundantly clear from the application of this methodology to the extant Marin test results was that the 1966 Convention requirements for minimum forward hatch strength were of the order of magnitude of 50 per cent of the appropriate level. This represents a very serious deficiency. It is no exaggeration to say that the maintenance of this minimum requirement in an international convention poses what, by modern standards, is an unacceptably high risk of loss of life in extreme sea conditions. Although at least one of the leading classification societies was unwilling to concede the inadequacy of the Convention, it is an inescapable fact that IACS had by 1997 agreed on the unified requirement known as UR S21. This, as many of you know, laid down a formula for the calculation of minimum forward hatchcover strength. In broad terms its application to bulk carriers of the size of the Derbyshire produced almost a doubling of the 1966 Convention requirement. In the course of the hearing of the Formal Investigation there developed a sharp divergence of view between some of the experts and LRS as to whether this formula produced adequate minimum strength requirements. Reliance was placed on model testing work that had been done at Strathclyde on a capsize model and which appeared to show loading of 81.56 KPa experienced at zero speed and with a significant wave height of 14.74m. It became absolutely clear in the course of the hearing that, although the Convention minimum strength requirements were demonstrably inadequate, there necessarily remained a serious question mark over the adequacy of the UR S21 formula. What also became clear was that, where in the course of 1992-7 IACS had come to accept this formula, which appears to have originated in its main features from work done in the US, nobody had more than the most sketchy understanding of its conceptual foundations. In particular the court received no satisfactory explanation from anybody as to the need for introducing a square root into the formula. The better view seemed to be that it might give a useful result for vessels of some dimensions but not for others. Clearly, if any serious attempt was to be made to replace the Convention’s requirements it would be necessary to identify a replacement formula, but if one could
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not be confident in the conceptual purity of UR S21, how could it be sold to the international community, even if it appeared more or less to do its job for some bulk carriers? The only sensible way out of this difficulty was to embark on a further series of model tests at Marin based on a specification directed to resolving the basic issue as to the appropriate formula. It will be well known and, if it is not, it ought to be, that on Day 49 of the hearing the UK Government by the Department of the Environment, Transport and the Regions made it known that it would, in principle, be prepared to finance the conduct of a further agreed model-testing programme if that course were recommended by the court. When I indicated that I proposed to make such a recommendation, Lloyd’s Register without delay canvassed the other numbers of IACS as to whether there could be developed a jointly agreed test specification for such further tests so that arrangements could be made for such tests without delay. I was able to discuss with representatives of the Department and Lloyd’s Register and with the help of my adviser, Prof Van Grugthausen a great deal of the detail which went into that specification. The remarkable feature of this was that it was also signed and sealed before ever my Report came to be written. That is significant. It represented a recognition of the urgency of the need for dealing with the 1996 convention and it built on the excellent working relationship which we had been able to create between the different experts during the course of the hearing. The intervention of the Department in support of the further research programme was a highly commendable contribution to the quest for international ship safety. IACS is also to be congratulated on the rapidity of its response. Without that programme no further effective international progress would be possible. It was against this background that I also recommended that there should also be agreed between Lloyd’s Register, IACS and the Department a specification for the statistical extrapolation of values of extreme seas loading from the date to be derived from the tests, and that this statistical work should be done by Professor Tawn who had already made such a major contribution to the work of the investigation. The Report went on to recommend that, when this further research had been done, IACS should, as a matter of priority, proceed to review the data and the statistical extrapolations in conjunction with the DETR and that they should endeavour to agree whether the URS21 level of protection accorded with the objectives of such minimum strength formula identified by the Report. In the course of preparing this evening’s lecture I have noticed that the recommendation in para 11.42 (i) of the Report contains an obscure cross-reference which has been printed as (1-7). In fact I am able to issue here and now a supplement to my Report by way of corrigendum. The reference is of course to para. 11.39 sub. paras (1) to (7). I am totally confident that both the Department and IACS have already spotted this, but if they have not, they now know the full thrust of the recommendation. Indeed, it is perhaps worth recalling what those objectives were. At the risk of an irrebuttable accusation of lack of modesty, I quote them now because it seems to me that they go to the very heart of the required decision – taking directed to a new formula: “(1) The overriding objective of any such formula must be to provide to survivability of the vessel in question in any realistic extreme condition that it may encounter during its service.
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(2) It is essential that there should be developed a self-contained composite formula which, subject to a minimum freeboard, provides for variable hatch cover strength relative to levels of freeboard additional to the minimum level. (3) For the purpose of developing this formula the logical starting point is to identify the relevant realistic extreme conditions in terms of significant wave height, modal period and expected type and from this to calculate the significant wave amplitude. (4) It is then necessary to calculate the significant relative vertical motion of the vessel, that is to say the overall degree of magnification of relative motion with reference to wave elevation, at the relevant position on the vessel. The data necessary for this exercise is ideally to be derived from model testing. (5) The next step is to calculate the extreme relative vertical motion at the relevant positions on board the vessel for a defined risk level. That risk level would sensibly be set at a low value, perhaps as low as 1 per cent for a storm duration of 3 to 24 hours. There must be a factor to account for negative nonlinearity. (6) It is next necessary to calculate extreme freeboard exceedance from the still waterline to the relevant places on the vessel, such as the top of the hatch cover for the defined risk level. (7) Finally it is necessary to calculate the extreme impact pressure head on the hatch covers for the defined risk level. Here again further model tests are necessary to establish the relationship between varying values of freeboard exceedance at any given location on the vessel and the impact pressurehead. The Report further recommended that IACS and the Department should endeavour to agree the details and values of a formula to replace URS21 so as to provide a clear and logically structured calculation of the appropriate level of protection (based on limit state design) whether the same as or different from USR21 and that such minimum strength formula should be introduced as soon as possible by the members of IACS as part of their classification rules. I now come to what is probably the most controversial part of the recommendations. Although the level of protection specified by USR21 was for many vessels far in excess of that specified by the 1966 Convention, that requirement only took effect for vessels built under contracts entered into on or after 1st July 1998. Although 96% of the world’s bulk carrier fleet are classified by members of IACS, the vast majority of the vessels now afloat were contracted to be built before 1st July 1998. These either comply with the minimum hatch strength requirements of the 1996 Convention or with the new requirements which certain members of IACS, not including CRS, had introduced to increase minimum hatch cover strengths to take effect during the 1990’s and before July 1998, but to levels lower than URS21. It is likely, therefore, that there are several hundred bulk carriers now afloat which were constructed with no
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greater protection that that provided for by the 1996 Convention. Of those several hundred about 60 are cap-size and comparable in dimensions to the Derbyshire. So when if and when a new formula can be arrived at, should it be applicable to this existing fleet? If it were to apply retrospectively a good deal of conversion work would be involved. Estimates of the cost of fitting strengthened forward hatch covers vary quite widely. It is not necessarily simply a matter of replacing the No.1 and No.2 hatches: it may also be necessary for some vessels to have additional strengthening in way of the hatch coverings. On the basis of the evidence before the Investigation I concluded that the additional cost without strengthening of adjacent parts was not likely to exceed £100,000, i.e. $145,000 and, inclusive of strengthening, was not likely to exceed £150,000 ($218,000). However, I am told that since then widely divergent estimates have been obtained for existing vessels, ranging from £97,400 to £436,000. I suppose it all depends whether you go for this work to Skaramanga or Singapore. However, in principle, the prospect of leaving existing bulk carriers in their present condition with forward hatch covers compliant with the Convention so far below what are likely to be minimum requirements, I would suggest, is quite unthinkable, even if the cost is in the upper half of that range. It may be objected that the incidence of bulk carrier losses is too small to justify requiring ship owners to incur expenditure of this order, particularly when profit margins are slender. However, if the new requirement were to be expressed as a formula which left it to each shipowner in agreement with his classification society either to increase the minimum permissible freeboard of the vessel as an alternative to strengthening the hatches, this would provide some of means of avoiding immediate expenditure on hatch strengthening. It would of course have the effect of reducing available cargo capacity, but that might be preferable, particularly for a vessel near the end of its trading life. By this device classification societies may find it easier to sell a new hatch cover regime to their owners. I have referred already to the second major problem about the safety of existing bulk carriers, namely the difficulties of monitoring the incidence of bow flooding. Amongst the specific recommendations made by the report are:(1) that there should be advice to all masters about the dangers of bow flooding; (2) electronic indication on the bridge of open or damaged ventilators and air pipes; (3) electronic indication on the bridge of displacement of foredeck hatch lids and of their becoming unsecured in the course of the voyage; (4) installation of lighting and video cameras on the foredeck of capesize bulk carriers; (5) electronic indication on the bridge of bilge levels in forward spaces. There are also other important recommendations which go to the watertight integrity of the bow. Notably:
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(1) a research programme to investigate minimum strength requirements for ventilators and air pipes (2) research into improved securing devices for store hatch lids (3) improvements to the methods of sealing sparking pipes (4) research into the minimum strength requirements for securing fittings, such as winches, to the foredeck (5) research into independent pumping systems for dealing with bow flooding At this point I would like to emphasise one very important lesson to be derived from the Derbyshire Enquiry. That is the way in which expert evidence was deployed so as to minimise hearing time and reduce costs. A system of joint expert meetings was established so as to enable the experts in particular disciplines to explore the prospects of arriving at agreement as to the maximum area of expert evidence possible. This led to a whole series of joint expert reports on all aspects of the evidence which was an extremely effective way of isolating the true issues. Nowhere was this more helpful than in relation to the interpretation of the wreckage video stills and the mosaic black and white photographs. But it was also of invaluable assistance in relation to recommendations as to future safety measures. It is impossible to say with any accuracy how much hearing time was saved by this joint expert meeting regime, but it must have been many days. But for that, there would have been very detailed cross-examination which could have lasted so long as to extend the overall hearing time by as much as 40 per cent. I strongly commend to all public enquiries which are in future concerned with the exploration of expert evidence that a similar system should be adopted. It is better to have days off from the hearing to let the experts maximise their common ground rather than to go floundering on through days of cross-examination. One of the disturbing matters to emerge from the Investigation was the cumbersome nature of international decision-taking in the field of ship safety. Once it is demonstrated that an international safety standard is completely inadequate, as was the case with the 1966 Convention requirements for minimum hatch cover strength, it is to say the least depressing to be told that the processes of international investigation and consultation in the IMO are so slow that nothing can be brought into effect for 4.5 years. Now I wonder whether there is a structural defect here. Although events of the last years have shown that the Maritime Safety Committee can act with an impressive sense of urgency (for it has taken a number of steps to implement the Report’s recommendations) there appears to be an inordinately long consultation period between the time when it takes its decisions as to amendment of the Convention. Another peculiarity of international maritime safety regulation is the dislocation between the IMO on the one hand and IACS on the other hand. IACS is of course a non-governmental association consisting of classification societies from only a handful of the members of IMO. Its members are the classification societies for 96% of the world’s bulk carrier fleet. It is therefore in practice in a stronger position than
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IMO to affect the state of safety of those vessels. It was for this reason that the Report recommended that IACS should go it alone on the bringing into effect of a new safety formula. So what has been done to implement the recommendations? There is no doubt that a very far-reaching and comprehensive international research programme has got under way. This has been strongly encouraged by the UK Court and has received support and co-operation from LRS and other classification societies. This is not the occasion to anticipate what decisions will ultimately be taken either by IACS or by IMO. However, in the field of minimum hatch cover strength, we have now moved well forward from the state of knowledge at the time of the close of the hearing of the Formal Investigation. The further work at Marin and the further statistical analyses by Professor Tawn both of which are now complete lead to the following indications. A remarkable total of 235 model tests have been carried out on three types of model: old design Capesize (similar to Derbyshire) new design Capesize and Panamax. The tests were extended to cover No. 2 hatch as well as No.1 and measured horizontal loading as well as vertical for the first time. The results as regards vertical loads confirm that the 1966 Convention minimum strength requirements are even more seriously inadequate than the Report concluded. They further suggest that vertical loading exceeds URS21 nominal design load requirements in both the intact condition and the damaged condition. The tests on the old capesize design model demonstrated that when the vessel was loaded down to its masks the maximum load on the No.1 hatch cover when there was no bow flooding was well in excess of the nominal design load under URS21. For the No.2 hatch both the 1966 Convention and URS21 requirements were at or about the level of the maximum load in the model tests. For the old design bulk carrier when there was flooding of No.1 hatch the loading on No2 hatch was far above the 1966 Convention and the URS21 minima. For the new design bulk cover in the non-flooded condition the maximum loading on No.1 hatch was also far in excess of the nominal design load under the Convention and URS21. This was also true when the forepeak was flooded. When the No.1 hold was flooded the maximum loading on the No.2 hatch was also seriously above URS21 nominal design load. There is thus the firm basis for an argument that URS21 does not deliver adequate minimum strata when the forepeak is flooded or when the No.1 hold is flooded. A very substantial increase in strength would seem to be required to cater for these flooded conditions. There is also some argument for concluding that even for the intact (in flooded) conditions URS21 needs to be beefed up. The results for the horizontal loading show much greater loading on the forward coaming of No.1 hatch than the vertical loading on the No.1 hatch cover. Also the horizontal longitudinal loading does not reduce as you go aft towards midships by anything like the same extent as does vertical loading. However, the transverse loading at No.1 hatch appears to be similar to the vertical loading. This was not an issue in the Derbyshire Investigation but the test programme has thrown up the need for further investigation and the probability that current design assumptions a s to required strength for hatch cover fastenings to avoid longitudinal displacement may be quite a substantial amount.
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The Maritime safety Committee of the IMO at its meeting three weeks ago decided that a whole raft of safety measures many of them to be found in the Derbyshire Report should be the subject of final decision-taking at its meeting to be held next December. Further, it was decided in principle to take forward the UK proposal to up date the cover design load criteria in accordance with recommendations put forward by the UK derived from the Marin test programme. It can therefore be anticipated with confidence that real and tangible progress in decision-taking in this field is likely to be made by the end of this year. Just as important in the area of prevention monitoring are the decisions of the Bulk Carrier Working Group of the MSC in relation to the fitting of water ingress alarms in all holds, ballast tanks, forward of the collision bulkhead and dry spaces, such as bosun’s stores, forward of the No.1 hold, excluding the chain locker. The MSC approved existing bulk carriers, whether with double or single side skin. Draft regulations making mandatory the installation of independent pumping systems in dry spaces forward of No.1 hold which are capable of being operated remotely, that is from the bridge. Again this requirement is to apply to new and existing bulk carriers. The regulations come into force on 1st July 2004 and apply to existing vessels as from their next annual survey after that date. Amongst the recommendations for decision taking at the MSC meeting in December 2002 is to be found a recommendation by IACS for the replacement or reinforcement of hatch covers forward of 0.25L of existing bulk carriers and then come the important words “to be equivalent to UR S21”. This is of really fundamental importance. IACS is meeting in September 2002 to consider the adequacy of URS21. No doubt its deliberations will take into account the suggested solutions to be derived from the Marin tests and Professor Tawn’s statistical work and the result of those deliberations will no doubt be brought to the attention of the MSC’s December 2002 meeting. I hope that IACS and the Department of Transport will jointly move Heaven and Earth to arrive at a common position by December 2002 as to what should be done about URS21 and the adoption of a new formula. It is not difficult to envisage a situation developing where the co-sponsors of the extended Marin programme put forward to MSC of the IMO not only inconsistent interpretations of those results, but also inconsistent recommendations as to what minimum strength requirements should be introduced by IMO. This would be most disappointing. If for example one looks as the time span elapsing between the publication of my Report and the implementation of the recommendations as to water ingress alarms and remotely operated pumping systems, a period of up to between 4 and 5 may elapse before existing vessels are required to comply. If changes in the hatch strength requirements are held up by technical disagreements as to the precise adequacy or inadequacy of URS21 it is not difficult to contemplate that the whole safety enhancement process may be delayed for years longer. Given that, whatever criticisms may be made about the adequacy of URS21 or about conceptual priority, it certainly provides for substantially enhanced minimum protection, it is to be hoped that IACS and the Department will be able to reach a common position as to what steps should be taken without further delay to make those hundreds of bulkcarriers whose hatches now comply only with the 1966 Convention materially safer. I would therefore emphasise the need for those two parties to bend over backwards to continue their highly commendable co-operative efforts to avoid disagreements, which might have the effect of paralysing or arresting further rapid progress by MSC.
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I am very far from wanting to suggest that nothing has been done to give effect to the Report’s recommendations. It can be appreciated that the progress of consultation and discussion takes a lot of time but although the big decisions remain outstanding there have been some concrete achievements. Notably the IMO’s MSC’s Maritime Guidance Note entitled Advice on the Dangers of Flooding of Forward Compartments. This is a notice to masters, owners and managers. A reading of these recommendations that IMO has set out to focus the attention of masters on the serious problems that may arise from flooding of the forepeak READ: A great deal of what I have said has been highly technical in content. Investigations of this kind inevitably deal in complex details. But it is not implementation of the recommendations which is what really matters. The recent loss with all hands of the Cyprus registered bulk carrier, the Christopher, of about the same size as the Derbyshire is a salutary reminder of just how vulnerable these vessels can be in certain sea conditions. the precise cause of that disaster has yet to be fully investigated. It is hoped that an underwater survey can be arranged. That is a matter currently under consideration by the UK Department of Transport. Whatever may emerge from that all of us who have been concerned with the safety requirements for such vessels cannot but feel a sense of urgency in achieving agreed international levels of protection which are fixed at the right point to save lives. If we can get to this point in the very near future those who lost their lives on these vessels will not have died in vain.
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