Many of you will have seen the Load Line markings on the sides of seagoing ships, some may even have wondered what they are for. The markings are also commonly known as the Plimsoll mark in honour of the British politician who, in the 1870s, was responsible for the UK legislation which curbed the loss of life caused by the foundering of over-laden ships and from ‘coffin ships’ (over-insured ships that were worth more to their owners when sunk than when afloat).
In the image above, the circle with the horizontal line drawn through its centre shows the deepest draft to which a ship may be safely loaded in seawater at summer temperatures (i.e. do not fill past this mark!) while the TF, F, T, S, W, WNA load lines to the right of the circular mark show how deep the ship may be loaded when it is sailing in waters with differing temperatures and densities (Tropical Fresh, Fresh and the seawater load lines for Tropical, Summer, Winter and Winter North Atlantic). A ship is prohibited from taking cargo onboard that would cause the relevant Load Line mark to be submerged i.e. it would then be illegally overloaded.
The load line mark fixes the maximum allowable draft and thus how much cargo (deadweight) any particular ship may carry (oil, iron ore, bananas, grain, cars, chemicals etc. etc.) and it may be said that the price of just about everything we come across in our daily lives is thus affected to some greater or lesser extent by the positioning of these small marks on the sides of a ship.
The location of these marks is governed by the rules of an International IMO (UN) Convention with their placement determined for each particular ship by means of a standardised, detailed calculation which takes into account the ship’s type, size, proportions, buoyancy, strength, stability etc. The vertical distance of the Load line mark from the upper deck is known as the freeboard and in general terms the greater the freeboard, the safer the ship will be. However the downside to having a large freeboard is that the ship’s ability to carry payload is reduced.
The first International Load Line Convention was held in 1930 and the second was held in 1966. As far as the MV Derbyshire is concerned, it is the regulations of the 1966 Load Line Convention that are of interest.
1966 Load Line Convention
By the mid 1960s, the world’s leading maritime nations, freight companies, ship owners, insurers and Classification Societies had become aware of the fact that the 1930 Load Line Convention’s regulations were out of date and that due to advances in ship design, construction standards and technology it would have been possible for the more modern ships, that were then joining the fleet, to load to a deeper draft and thus be able to carry more cargo. In particular the fact that welding had superseded riveting in ship’s hulls and that steel hatch covers had overtaken wooden hatch boards and canvas covers now meant that the world’s fleet was being replenished with new vessels that were stronger and more seaworthy than those envisaged at the time of the 1930 convention.
In 1966, the UK then had the largest merchant fleet in the world and thus a rewrite of the Load Line Convention was something that the UK Government was obliged to take a keen interest in. UK ship-owners were obviously very concerned with their vessels’ payloads; hence the positioning of the Load Line marks on the sides of their ships was of crucial importance to their business, the costs of transporting goods and to the profitability of international trade.
Bearing this in mind, it is easy to appreciate the UK Government’s position at the start of the 1966 Load line Conference (page 149 in the Derbyshire RFI report advises us that):
The UK’s material objectives were to seek deeper loading (reduced freeboard) for tankers and dry cargo ships with steel hatch covers.
While most nations had similar objectives, the principle debate at the International Conference was on the accompanying technical measures, safeguards and standards that would need to be imposed to allow the additional cargo to be carried safely at sea. The outcome that most delegates sought from the Convention were affordable, efficient ships which would be able to carry more cargo, without a reduction in the safety levels that were being achieved prior to 1966 Convention.
An important part of the debate on safety concerned the minimum technical standards that would be required for steel hatch covers. Commenting on this event, the Derbyshire RFI report (page 151) suggests to us that the UK’s delegation fought valiantly for stronger hatch covers on vessels of Derbyshire’s type, against overwhelming international opposition, but that unfortunately they failed in their quest.
The Ministry of Transport and the UK delegation did all that reasonably could be done to obtain agreement to enhanced hatch cover strength. The failure to persuade a majority of the 52 national delegations to accept these proposals has to be seen against the background …etc.
However, this information from within the RFI report gives a somewhat false impression on the actual course of events at the 1966 Conference. At that time, the UK’s primary objective was to obtain deeper loading for bulk carriers and tankers, while their proposal for enhanced hatch cover strength was only of secondary importance - merely a ‘safety’ concession which would give a degree of credibility to their argument for deeper loading. (In fact it was not even a concession on the UK’s part, as existing national legislation already contained enhanced strength requirements for hatch covers on UK ore carriers that were sailing with ‘tanker freeboards’ see Fig. 2. below).
The 1966 Load Line Conference concluded on 5 April 1966 and Statutory Instrument number 1053, The Merchant Shipping (Load Lines) Regulations, brought the regulations of the Load Line Convention into force in the UK on 21 July 1968. The explanatory text at the end of this UK instrument gives a brief summary of the changes brought about by the new regulations:
The MV Derbyshire Re-opened Formal Investigation (RFI) and the Load Line Rules (see pages 145-161 in the Derbyshire RFI report)
...The principal change is that new ships as defined in section 32(4) of the 1967 [Load Line] Act are required to comply with more stringent constructional requirements (conditions of assignment) specified in Schedule 4. This qualifies them for reduced freeboards under Schedule 5, thus enabling them to be more deeply loaded than heretofore.
The final report from the Derbyshire RFI does not mention the commercial interests that were at play during the 1966 Conference and focuses instead on elements of the technical debate between the experts from the world’s maritime nations. As mentioned previously, in this limited scenario (and with hindsight), the UK Government has managed to cast itself in a heroic role, fighting a laudable battle for increased safety standards on seagoing ships and only failing to achieve their goals when faced with overwhelming odds.
While the text in the Derbyshire final report may make pleasant reading for our Government officials it does not correspond with the facts of the case, as the official records from the 1966 Load Line Conference show:
The contents of the above document show that the UK delegation wished to attain drafts for seagoing ships that were significantly deeper than those previously granted to ore carriers i.e. they were seeking freeboard reductions and drafts for ore carriers that went far beyond those allowed for ‘tankers’ under the 1930 Convention (the UK’s proposals for reduced freeboards are indicated in red, in the sketch on the following pages (Fig 3.) - allowable ‘tanker freeboards’ are also indicated in the same sketch by the dotted line – ‘1930 Tanker’).
It is important to note that the UK’s proposal for stronger hatch covers at the 1966 Conference was directly linked and secondary to their proposals for reduced freeboards. When the majority of delegates at the Conference did not accept the UK’s proposals for reduced freeboards (deeper loading), the UK delegation lost much of their interest in hatch covers and did not press on with their case for an enhanced standard of strength.
The Derbyshire RFI final report [**], however, manages to give the false impression that the UK’s objective was merely to seek ‘tanker freeboards’ for ore carriers, facilitated by stronger hatch-covers when, in fact, the UK was seeking a far greater reduction in freeboards than had been the practice in the years prior to the 1966 Conference.
Fig 2. The UK’s standard practice for allowing reduced freeboards on ore carriers, prior to the 1966 Load Line Convention, is outlined in the Board of Trade minute below:
Fig. 3 The graph shows the minimum freeboards allowed by the 1930 Load Line Convention for Steamers and Tankers, together with the UK’s proposed curve of freeboards for bulk carriers as presented by delegates at the 1966 Load Line Conference. The final agreed curve of freeboards (B-60 - as defined in the regulations of the 1966 Load Line Convention), which applied to the Derbyshire, is also shown.
On page 17 of the Derbyshire RFI final report, Justice Colman states that the UK Government cannot be criticised for failing to secure an agreement to its proposals for increased hatch cover strength. We’re not quite sure that we agree with him on that point: the UK government could certainly have been criticised for not implementing the Convention’s provisions for hatch cover strength in their entirety and also for interpreting the Convention’s minimum requirements for hatch cover strength incorrectly:
- Regulation 27(7)(c) of the 1966 International Load Line Convention was partially omitted from the text of the UK’s 1968 Load Line Regulations (the part that is underlined below). This regulation was very important in that it stipulated minimum standards for hatch cover strength when reduced freeboards were allowed (as in the Derbyshire’s case)
27(7)(c)… provided that the Administration is satisfied that:
(c) the covers in positions 1 and 2 comply with the provisions of regulation 16 and have adequate strength…”
This omission meant that there was no statutory requirement for the hatch covers on UK bulk carriers, with reduced freeboards, to have adequate strength; the UK regulations merely stated that the hatch covers should comply with the strength requirements of regulation 16. In regulation 27(7)(c), the Convention clearly stipulates that it is the responsibility of individual Administrations (e.g. the UK Government) to satisfy themselves that, on ships with reduced freeboards, the hatch cover strength is adequate.
- Regulation 16 of the Load Line Convention, which lays down minimum hatch cover strength requirements, was also applied improperly by the UK in that the authorities allowed an erroneous formulation for hatch beam section modulus to be used to determine hatch cover strength - one which would consistently underestimate hatch cover stress levels by about 10% (the error could lead to deficient hatch covers being installed on UK ships and, as discussed previously [LINK] the hatch covers installed on the Derbyshire were deficient in strength because of this error - see Appendix 1).
- The UK’s Load Line regulations, which entered force in 1968, contained a lower strength requirement for bulk carrier hatch covers than that contained in the regulations they superseded (the UK’s requirements for hatch cover strength were reduced by about 15% when the 1968 regulations came into force - see Appendix 1.)
- In 1966 the UK’s merchant fleet was the largest in the world and the UK Government of the day (Harold Wilson’s Labour government) looked upon the 1966 Load Line Convention as a commercial opportunity that would enable deeper drafts to be assigned to cargo vessels in the UK fleet.
- At the time of the 1966 Load Line Conference, the UK delegation proposed a significant reduction in freeboards (~ deeper drafts), which did not gain the support of other maritime nations and the resulting regulations for freeboards were far more modest in scope (for a vessel like the Derbyshire the difference between the freeboards initially proposed by the UK and the freeboards that were included in the 1966 Load Line Convention would amount to about 5000 tonnes in lost cargo capacity).
- A provision for enhanced hatch cover strength was also included within the UK’s proposals for reduced freeboards, however, when their proposal on freeboards did not find support, their case for increased hatch cover strength was dropped.
- The 1966 Load Line Convention’s final regulations contained a minimum strength standard for hatch covers, together with a provision whereby this minimum strength could be increased on vessels that were assigned reduced freeboards. The UK did not implement this provision.
- If the UK Government had been seriously concerned about hatch cover strength standards on bulk carriers with reduced freeboards, then they could have taken action to impose higher standards on UK ships – the regulations of the 1966 Load Line Convention actually encouraged such a practice but left the detail of such standards to the discretion of individual nation states. On page 153 of the Derbyshire final report, Justice Colman accepts that the UK Government could have applied more stringent hatch cover strength standards than those laid down in the Convention, but then justifies the authorities’ subsequent inaction with the dubious notion that, had more stringent standards been adopted by the UK, then this would have resulted in “serious damage to the British national interest as a leading merchant marine flag state”.
(Though it is difficult to accept that a few extra tonnes of steel on the hatch covers of a large, new, bulk carrier would have led to the collapse of the UK merchant fleet!)
- The main conclusion that emerged from the Derbyshire public inquiry was that the 1966 Load Line Convention regulations for hatch cover strength were seriously deficient and that it was this factor, together with severe weather, that led to her loss.
- We would suggest that, if the regulations of the International Load Line Convention had been implemented in full and also interpreted correctly by the relevant UK authorities, it is possible that the Derbyshire would have survived the perils of Typhoon Orchid.
[*] Report of the Re-opened Formal Investigation (RFI) into the loss of the MV Derbyshire (page 211) - official questions and answers :
“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?
16.8 Is that design satisfactory in the light of what is now known?
- No: seriously deficient.”
[**] RFI report Para. 10.21 “The stronger hatch covers proposed by the UK were put forward in response to application to bulk carriers of the tanker freeboard”