Unfinished Business

One of the main reasons for carrying out a Formal Investigation into a shipping disaster is to determine its causes so that safety lessons can be learned and action taken to prevent similar tragedies re-occurring. Following the Gaul and Derbyshire inquiries we have found out, however, that this is not really the case: the protection of the financial interests of a few political and corporate operators have primacy over all other considerations, including safety.

In the run up to the 2004 Gaul and 2000 Derbyshire formal investigations, and subsequently, a lot of public money was spent and a lot of work was carried out in order to determine the causes of these two maritime disasters and to propose new measures that would improve safety. The causes for the tragedies were well obscured and, as for the safety measures recommended during those two inquiries, when it came to the final stage - the implementation or concrete action stage – matters, somehow, fizzled out.

Trawler Gaul lost in 1974 with all 36 crew

It is doubtful whether the four safety recommendations that came out of the Gaul 2004 Re-opened Formal Investigation (RFI) will ever come into effect. They had not been implemented in January 2007 when we first raised this matter [link] and they have not been implemented since.

The fact that the four safety recommendations, put forward by Justice Steel (the Wreck Commissioner in the Gaul RFI), are based upon false premises, are inappropriate and will therefore not be effective in preventing future loss of life, may be one of the reasons why the Government prefers them to be shelved and quietly forgotten.

OBO MV Derbyshire lost in 1980 with all 44 persons onboard

The Formal Investigation into the loss of the MV Derbyshire concluded in 2000 and its final report was published on 8 November of that year. The principal finding and recommendation to come out from the Derbyshire RFI was that the regulations for hatch cover strength were seriously deficient and that the International Convention on Load Lines (1966) needed to be amended urgently to rectify this shortfall.

The regulations of the Load Line Convention were thus redrafted at IMO to include requirements for specially strengthened hatch covers to be fitted to the forward cargo holds of all new cargo ships (not only bulk carriers). The new amendments were finalised at IMO [*] in 2002 and came into force Internationally in 2005.

However, they did not legally come into force for UK flagged vessels at the same time because the UK’s own Merchant Shipping legislation had not been amended to give legal force to the new Load Line Convention requirements for hatch covers. Today, the legislation still has not been revised.

The relevant UK rules are contained in Statutory Instrument (SI) 1998 No. 2241: The Merchant Shipping (Load Line) Regulations 1998.

There is no reason why these rules could not have been amended in a timely manner; in fact, the UK Load Line regulations were recently modified by Statutory Instrument (SI) 2005 No. 2114, so as to implement the following changes:

“……… in the definition of "pleasure vessel" or "pleasure craft", as the case may be, for each reference to "husband or wife" substitute "spouse or civil partner".

Now, that was extremely important - and also revealing of our government’s legislative priorities as regards Maritime safety.

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[*] International Maritime Organisation

Non-compliance with the Standards

A critical look at the design of the Derbyshire’s hatch covers and at the Court’s view that the hatch covers complied with the ‘standards applicable at the time she was built

Synopsis

In 2000, the Re-opened Formal Investigation (RFI) into the loss of the Derbyshire concluded that that the Tees built bulk carrier had been lost, during typhoon Orchid, as a result of significant hold flooding following the structural failure of the vessel’s main cargo hold hatch covers due to heavy seas.
The Court also concluded that although the vessel’s main cargo-hold hatch covers had been designed to meet the international strength standards applicable at the time she was built, those strength standards were severely deficient, and it was this regulatory deficiency that was crucial to the vessel’s loss.

Extracts from sections 7 and 16 in the final report of the RFI:

"7.16 At the time of the DERBYSHIRE’s last voyage her
hatch covers complied with the minimum strength requirements of ILLC 66 and of the Lloyd’s Register of Shipping Rules.

[…]

16.7 In so far as material to the loss of the “DERBYSHIRE” was the design of the hatch covers of the “DERBYSHIRE” in accordance with the standards applicable at the time she was built?

- Yes.

16.8 Is that design satisfactory in the light of what is now known?

- No: seriously deficient. The design strength was inadequate to withstand the green water loads likely to be sustained during extreme sea conditions, which a vessel might encounter during her service life."

The outcome of the RFI was, thus, able to deflect any suspicion of blame away from the vessel’s builders and the Classification Society, both of whom could have been subjected to hostile litigation, had the design or construction of the hatch covers been found to fall short of the required norms.
However, independent calculations show that the court’s conclusion, that the Derbyshire complied with the standards applicable at the time she was built, is not wholly correct. The results of these calculations are summarised in the pages that follow below.

Hatch Covers - applicable standards

The minimum strength standard [1] that the Derbyshire’s hatch covers was required to meet was laid down within the 1966 International Load Line Convention, additionally this minimum strength standard was incorporated within the construction rules and regulations of the organisation (Lloyd’s Register) that assigned the Derbyshire with its +100 A1 Classification and its International Load Line certificate.

Strength Calculations

It is unfortunate that the Derbyshire was not constructed to meet the version of Lloyd’s Rules that was in force prior to the introduction of their 1968 Rule amendments, as that earlier version (first introduced in 1963 and valid until 1967) contained more stringent requirements for ore carrying deep draught vessels such as the Derbyshire.

What is more unfortunate, however, is that, as our calculations show, she didn’t comply with the standards that were introduced later (i.e. at the time of her build). This latter non-compliance was not acknowledged during the course of the 2000 RFI, and whether or not the Derbyshire would have survived, had her hatch covers met the relevant standards, remains, therefore, debatable.

Extracts from Lloyd’s Rules 1967
Ships specially
designed for carrying ore
Para 6020 (page 254)

“Hatch Covers

Steel hatch covers are to be in accordance with D 2326 and the
scantlings determined from the formulae given in table 43 note 6. When a draught in excess of the cargo ship draught is desired, the section modulus and moment of inertia of the stiffeners and thickness of the plating are to be increased by 15 per cent.”

In 1968, Lloyd’s rule requirements for hatch cover strength were reduced by 15% to bring them into line with the requirements of the 1966 Load Line Convention.

In the following pages the strength of the Derbyshire’s number one cargo-hold hatch covers has been evaluated and compared to the minimum strength required by both the Load Line convention and Lloyds Rules. The minimum strength requirements that were given within the Load Line Convention and Lloyd’s Rules were the ‘standards applicable at the time she was built’. No other standard is relevant.

The summarised results from the strength calculations that are given below include values obtained from classical manual calculation methods (simple beam theory), empirical methods (to give section modulus required by Lloyd’s rules) as well as finite element modelling and analysis.

The results from each of the above methods show that the Derbyshire’s No. 1 hatch covers did not meet the minimum strength ‘standards applicable at the time she was built’.

Derbyshire no.1 hatch cover construction (mild steel)

The Derbyshire’s number 1 cargo hold hatch opening was protected by two hatch covers arranged Port and Starboard of the vessel’s centreline which slid outboard to open and inboard to close. When closed, each hatch cover was supported on three of its sides by the upper deck hatch coaming structure. The fourth side of the port hatch cover mated with the fourth side of starboard hatch cover at the vessel’s centerline. There was no structural support for the fourth side of the hatch covers at the vessel’s centreline other than at their fore and aft ends where they sat upon the hatch coamings.

Each hatch cover panel was arranged with steel top plating and four side plates around its perimeter. Longitudinal and transverse stiffening members were provided on the underside, i.e. ten main, fore and aft longitudinal stiffeners and three main transversal girders (side, centre, side); these stiffening members were ‘simply supported’ at their ends by the four hatch cover side plates.

Main fore and aft hatch cover stiffeners – strength and stress calculation

Strength

1. Stress calculation using simple beam theory:

The stresses within the hatch stiffener can be calculated from the section properties that are detailed above in conjunction with the loading that is given within the Load Line Convention:
The fore and aft stiffeners are simply supported at their ends by the hatch coamings:

(1) For mild steel, maximum allowable stress = 4100/4.25 = 965 kg/cm2
Hatch cover fore and aft stiffener spacing = 0.994 m
Total pressure load on one stiffener = W = 14.72 x 0.994 x 1.75 = 25.605 tonnes
Approximate self weight of one stiffener = Section Area of 1 stiffener x L x density:
Self weight of stiffener = (0.994 x 0.011 + (0.61 + 0.46)/2) x 0.0105 + 0.28 x 0.025) x 14.72 x 7.8 = 0.351 x 7.86 = 2.725 tonnes

From simple bending theory: the maximum bending moment in the stiffener is at its mid point = WL/8
M = (25.605 + 2.725) x 14.72/8 = 52.1272 tonne metres

Simple bending theory:
M/I = σ/Y = E/R => stress = σ = bending moment/section modulus

Maximum bending stress = 52.1272 x 105/4799.43 = 1086.11 kg/cm2 (this exceeds the maximum allowable stress in (1) above)

Load Line Convention requirements:

The minimum required Section Modulus (I/Y) to give stresses below 965 kg/cm2 can be easily determined:

From simple bending theory (M/I = σ/Y) => M/σ = I/Y = 5212720/965 = 5402 cm3

Summary of strength standards:

The table below provides a summary of the strength standards that were current during the period in which the Derbyshire was designed and built. The shortfall in the required strength of the hatch cover stiffeners is also indicated.

* It would appear that the Lloyd’s Register formulation for minimum section modulus does not include an element for the stiffener’s self-weight. This implies that their rules at that time would consistently give strength requirements that would fall below that set to meet the stress criteria of the 1966 Load Line Convention. The strength required to support the stiffener’s own self weight is significant (on the Derbyshire each stiffener weighed approximately 2.5 tonnes and was 14.7m long); neglecting this factor would mean an approximate 10% shortfall in required strength when the Lloyds formulation was used.

Although the percentages shown in the above table do not appear to be dramatic, it should be noted that these are shortfalls on a strength standard that is meant to provide a statutory minimum. There is no reason, other than cost savings, why designers should not exceed this statutory minimum by a comfortable margin.
The above concludes the summary of the traditional ‘rule - based’ approach to determining hatch cover strength requirements.

2. Strength and stress analysis of the Derbyshire’s hatch covers using the finite element method

It should be noted that the hatch covers on the Derbyshire were not solely provided with fore and aft ‘I’ section stiffening members (as discussed and examined previously) in addition three deep transverse girders were provided, arranged as indicated in the sketch on page 3. Effectively, this arrangement of longitudinal stiffeners and transverse girders formed what is known as a ‘grillage’ in structural analysis terminology.

The effect that these three additional girders would have on the actual strength of the hatch covers is debatable. There are two main possibilities: the girders would either increase the strength of the covers, if arranged effectively, or diminish the strength of the hatch covers, if not arranged effectively.

The Class Society’s rules in the 60’s and early 70’s did not specifically provide for grillage type hatch cover arrangements, and did not give detailed strength requirements for hatch covers that were arranged in this way. Manual calculations to determine realistic strength and stress levels in a grillage are quite complex.

The contemporary method for performing strength and stress analysis on two and three-dimensional structures is by means of finite element modelling.The Load Line Convention’s parameters are quite useful in this respect, as they lay down the loads that have to be applied together with the maximum allowable stress levels,. They neither specify how the hatch covers should be arranged nor give strength values for the hatch cover’s structural elements.

We have constructed two finite element models of the Derbyshire’s hatch cover structure:

i) Three stiffener model

This first model was used to determine the stress levels in a single longitudinal stiffener (for comparison with the results previously obtained from the traditional approach). Note that three stiffeners were included in the model to eliminate boundary effects. The transverse girders, although included, were not effective in this model

ii) The port side hatch cover model

One whole hatch cover was modelled to determine the stress levels in the stiffeners, girders, side and top plating. The stiffeners, girders, side plates and cover top plating were effective in this model.

Results

The results from the finite element analysis are best appreciated visually, the following comments are a brief summary of what the two analyses revealed:

Three-stiffener model: this model, which was typical for the 10 fore and aft main stiffening members of the Derbyshire’s hatch covers, revealed maximum stress levels of about 1000 kg/cm2 in the main longitudinal stiffener flange. These stresses correspond with those obtained from traditional beam and bending theory, and, again, they exceed (by about 5%) the allowable stress parameters that are laid down within the Load Line Convention. ">

Undeformed stiffener model viewed from underside

Undeformed stiffener model viewed from above

Deformed model with seawater loading at 1.75 Tonnes/m2 (plus self weight) - Viewed from above

Deformed model with seawater loading at 1.75 Tonnes/m2 (plus self weight) - Viewed from the underside

Port side hatch cover model: this model revealed that the three main transverse girders were effective in reducing stresses in the longitudinal stiffeners to satisfactory levels. However, the girders themselves, together with the inboard hatch cover side plate to which they were attached, were not strong enough to take the additional loads that had been shed from the 10 longitudinal stiffeners. Stress maxima in the region of 1300 kg/cm2 were developed in the two transverse side girders, stress maxima in the region of 1400 kg/cm2 were developed in the single transverse girder, and stress maxima in the region of 1350 kg/cm2 were developed in the main inboard hatch cover side plate.

Undeformed hatch cover model viewed from above

Undeformed hatch cover model viewed from underside

Hatch cover - original and deformed structure

Hatch cover - original and deformed structure

Hatch cover - deformed structure - views

Hatch cover - deformed structure - view from above

Hatch cover - deformed structure - view of the underside

Conclusions

The stress levels in the transverse girders and longitudinal inboard side plate, as revealed by the FE analysis, significantly exceed the allowable stress levels that are given within the 1966 Load Line Convention. It is notable, that the stress levels in some areas are more than 40% above the statutory maxima. Elevated stress levels indicate that the hatch cover’s factor of safety against catastrophic collapse may have been significantly reduced. And a failure in the longitudinal inboard side plate could lead to a domino-like collapse of the remaining hatch structure.

On the basis of the calculations summarised above, it is clear that the strength of the Derbyshire’s hatch covers did not comply with the standards that were applicable at the time she was constructed, and that, therefore, the RFI statement to the contrary was incorrect.

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[1] Re: Strength

i) The required ‘strength’ standard within the 1966 Load Line Convention was the minimum strength that, when the hatch covers were loaded at a rate of 1.75 tonnes/m2, would produce stresses below the ultimate breaking strength of mild steel divided by 4.25 (a notional factor of safety of 4.25).

ii) The required strength standard that was contained within Lloyd’s Register’s construction rules was expressed as ‘minimum required section modulus’ - the rule requirements allowed the maximum stress values, that were permitted by the Load Line Convention, to be governed by a single parameter which could be calculated for each girder in each hatch cover ie if the main hatch girders had a section modulus that exceeded xxxx cm3 then the maximum stress levels within that girder would not exceed the values permitted by the load Line Convention when the cover was loaded at 1.75 tonnes/m2.

Discretion

Following on from our post of 26 October, below, we would now like to advise the Department for Transport has replied to our FOI request, and they even did so within the period prescribed by the law.

(You can read it in full at: http://www.whatdotheyknow.com/request/mv_derbyshire.)

Unfortunately, we did not find out much from that reply. As discreet as a confession box, the DfT officials would not divulge the identities of the participants in the Derbyshire presentation, arguing that this was "personal information".

The Department would not answer our question about the materials that were to be presented at the November 4th meeting either. We, therefore, had to insist (See our reply on the same site mentioned above)

The DfT, however, let us know that the Rt Hon John Prescott MP, although invited, was not going to attend the event.

Sometimes, of course, it is better to make yourself scarce.

MV Derbyshire - theories and factual evidence

In addition to our earlier posts published on this site, we would like to provide further comments and clarifications on the outcome of the Derbyshire RFI, and put forward a different possible scenario for the loss of the vessel. (Please see the attached DOCUMENT)

The 2000 inquiry maintained that heavy weather damage to a number of ventilators and air-pipes at the fore end of the vessel had allowed seawater to enter the hull’s forward spaces and cause the vessel to trim by the bow. It also concluded that this forward trim would have enabled heavy seas to break on and over the number 1 cargo hold hatch covers and subject them to significant loading. This ‘green sea’ loading was deemed to have exceeded the collapse strength of these covers causing them to fail, and leading to the flooding of number 1 cargo hold and hence even more trim. The process was said to have repeated on the number 2 and then the number 3 cargo hold hatch covers, and so on until the vessel sank.

The RFI loss scenario thus considered that the forward trim of the vessel (brought about by flooding of the stores spaces, chain lockers and forepeak) was the initiating factor in a chain events leading to the final loss.

Whilst the evidence indicating that the Derbyshire’s hatch covers had failed due to seawater loading is conclusive, the court was unable to demonstrate in a satisfactory manner that the vessel’s slight forward trim was indeed the causative factor of that failure.

Having noted the limitations of the MARIN model tests used by the RFI, we argue, on the contrary, that the forward trim that was taken into account would not necessarily have been sufficient in itself to bring about the tragedy.

The loss of forward freeboard due to flooding and trim, about 1.3m only (excluding flooding of the Fuel Oil Deep tank), was not of a magnitude that could significantly alter the ‘ballpark’ hatch cover loads expected to arise from the large waves and ship motions generated by typhoon Orchid. The hatch covers in this trimmed condition would still be about 8.9m above the sea surface and only about 630 mm below their normal position, with the ship in an undamaged but fully laden condition.

Therefore, the small trim by the bow could not realistically and satisfactorily explain the cycle of floodings and the resulting sinking that were suggested by the inquiry. Yet, under the label of unknown and unforeseen causes for the loss of the vessel, the RFI piled together and discarded many other possible alternatives.

Out of this class of unforeseen causes, we have now decided to present one alternative theory in which the spare propeller carried onboard the vessel, due to its position and location on the upper deck as well as due to its securing arrangements, becomes detached from its deck supports and wreaks damage to adjacent weathertight structures.

The damage to these structures, it is argued, would lead to flooding, the failure of the hatch covers, flooding and ultimately to the loss of the vessel.

Quite understandably, this alternative scenario, again, opens up discussions about liability and compensation, and this was something, which the RFI tried very hard to avoid.

(More details, explanations, diagrams and supporting evidence are contained in the attached DOCUMENT)

The MV Derbyshire Presentation

In early November this year, the Department for Transport will be acting as host for a presentation on the 2000 MV Derbyshire RFI. It is going to be a modest affair - which is not being publicised - to be held behind closed doors, for the benefit of the Derbyshire families only. The guest of honour, it is touted, will be none other than the MP for Hull East, Mr John Prescott. (As the Minister responsible for the DETR, he was obliged to sanction the 2000 Derbyshire RFI – an inevitable decision, given the unsatisfactory nature of the original Formal Investigation and the new evidence obtained from the underwater surveys.)

The prospect intrigued us and stirred our curiosity to such a degree that we felt compelled to find out more about the event and to try to make sure that no more taxpayers’ money on securing Mr Prescott’s ‘legacy’ will be spent, and that no further loss of official repute or deliberate bamboozling of the Derbyshire victims’ families will happen.

Therefore, we have lodged a FOI request with the Department for Transport in order to get more details on this matter. The request can be seen at the following web address:

http://www.whatdotheyknow.com/request/mv_derbyshire.

The DfT kindly promised us a reply by the end of October.

Dry run for litigation

By way of preamble to the comments that will follow later on this site, we are now providing a brief explanation of what, in our view, appear to have been the interests, motivations and legal objectives behind the outcome of the Derbyshire Formal Investigation.

As we have mentioned earlier on our Trawler Gaul blog, the search for the truth in many formal investigations held in the UK has often been hindered by the adversarial aspects of these inquiries – aspects which render them not as much as investigative processes, but as cases of ‘shadow litigation’.

In a similar manner, the outcome of the Derbyshire RFI appears also to have been affected by the unequal leverage exerted by the most powerful of the forces competing in that formal investigation: i.e. the British government and the maritime establishment, i.e. the parties that would have stood to lose out from any results likely to lead to litigation.

Rather than simply establish the causes of the tragedy, the final report of the Derbyshire RFI sought, also, to exonerate the shipbuilders from any potential liabilities.

Thus, the RFI concluded that the design deficiencies that had led to the loss of the Derbyshire had not been due to negligence on the part of the shipbuilders, but to the unfortunate inadequacies in the international maritime legislation in force at the time of her build.

As the final report shows (see Annex 2 of the attached document) the court addressed a number of limited and leading questions, which appear to have been tailored in a way that would have allowed British Shipbuilders (i.e. the Government) to make use of one of the defenses provided under products liability legislation – i.e. the ‘development risks defense’ – to counter charges of negligence and claims for compensation, should these have later arisen.

This 'development risks defense' states:

“the state of scientific and technical knowledge at the time [the producer] supplied the product was not such that a producer of products of the same description as the product in question might be expected to have discovered the defect if it had existed in his products while they were under his control.”

Furthermore, the court’s final conclusions that the vessel’s deck fittings (mushroom ventilators, airpipes and windlass seating) were wholly in accordance with standards applicable at the time the Derbyshire was built - standards which today are no longer acceptable – was not, in fact, proven. On the contrary, photographic evidence from the wreck site indicates that these fittings were not wholly in accordance with the standards that applied at the time of build.

For a fuller and clearer explanation, please see the document published at THIS LINK.

(More to come)

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The document mention above can also be found at the following links:

http://www.scribd.com/doc/7437637/Derby-Shire-Shadow-Litigation

http://docs.google.com/Doc?id=ddpkgjpm_139cqjhnhhn

MV Derbyshire tragedy

The MV Derbyshire, a 91,655 gross tons bulk-carrier was was built in 1976 by Swan Hunter Shipyard, Teesside, for the shipping company Bibby Line. The vessel was registered at Liverpool and classified by LRS.

On 9 September 1980, during Typhoon Orchid, MV Derbyshire dissapeared off the south coast of Japan, with all hands on board (42 crew and two wives). She was, and remains, the largest UK ship ever to have been lost at sea.

The Report of the Formal Investigation (FI) held in 1987 first concluded that the loss of the MV Derbyshire had been due to a force majeure event, the vessel having probably been "overcome by the forces of nature in typhoon Orchid".

The wreck was eventually found in June 1994, during a search launched by the International Transport Workers' Federation and led by the American shipwreck hunter David Mearns. The search team were also able to deploy a ROV to survey the wreck and collect photographic evidence from the site.

Later on, using evidence from the underwater survey, the Investigation assessors purported - on the basis of a rope seen emerging from the Bosun’s store hatch opening and of an examination of the disposition of that hatch’s toggles - that the loss of MV Derbyshire had been caused by the negligence of the crew, who had allegedly failed to secure the hatch lid, which lead to fore end flooding and structural failure.

The discovery of the wreck prompted the British Government to re-open the Formal Investigation into the sinking of the vessel - investigation which began in April 2000. This time, the investigation reached the conclusion that the ship had sunk because of fore end flooding and structural failure, and as a result of inadequacies in the legislation in force at the time of build, and that the rope emerging from the Bosun’s store hatch opening was nothing more than post-casualty debris, thus absolving the crew of any responsibility for the tragedy.

The Investigation found that damage to the forward vents, hatches and equipment on the upper deck initiated the unfortunate sequence of events that led to the vessel's loss. Flooding of the vessel’s forward spaces through these damaged vents and hatches gave the vessel a trim by the bow, thereafter the main cargo hold hatch covers were subjected to seawater loading and collapsed – flooding number 1 hold first, then number 2 hold, then number 3, and so on until the vessel sank.

Several important questions, however, have remained unanswered:

1. The mushroom vents on the MV Derbyshire obviously failed. Were they therefore adequate?

2. The vessel had been issued with a Load Line certificate. But did the vents comply with the requirements of the Load Line Convention?

3. Did the construction and workmanship of these vents conform to the shipyard's or appropriate British standards?

4. Did the fillet welding on the windlass seat have adequate throat thickness and, was the workmanship satisfactory?

In due course, these questions and several others will finally be addressed.