ZESZYTY NAUKOWE NR 11(83)
AKADEMII MORSKIEJ
W SZCZECINIE
IV MIĘDZYNARODOWA KONFERENCJA NAUKOWO-TECHNICZNA
E X P L O - S H I P 2 0 0 6
Lech Kobyliński
New Load Line Rules – Success or Failure?
Key words: Safety of ships, load lines, deck wetness, International Maritime Organisation
New Load Lines regulations came into force on 01.01.2005. This is the result of the long time preparations within IMO SLF Sub-Committee. The work was aimed at the review of the provisions of the LL Convention and, in particular, revision of freeboard tables based on deck wetness concept. This aim was only partially achieved. The first part of the LL Convention including conditions of assignment was totally re-drafted, but freeboard tables were not changed. The subject of revising freeboard tables was eventu-ally deleted from the work programme of IMO.
Nowe prawidła o liniach ładunkowych – sukces czy porażka?
Słowa kluczowe: bezpieczeństwo statku, linie ładunkowe, zalewanie pokładu,Międzynarodowa Organizacja Morska
Nowe prawidła dotyczące linii ładunkowych weszły w życie w dniu 1.01.2005 r. po długich przygotowaniach w ramach Podkomitetu SLF IMO. Celem tych przygotowań była nowelizacja prawideł technicznych konwencji o liniach ładunkowych, a w szczegól-ności nowelizacja tabel wolnej burty, które oparto na zasadzie zalewania pokładu. Cel ten został tylko częściowo osiągnięty. Pierwsza część konwencji o liniach ładunkowych zawie-rająca warunki przyznawania wolnej burty została gruntownie przeredagowana, lecz tabe-le wolnej burty pozostały niezmienione. Sprawa rewizji tabel wolnej burty została odsunię-ta na czas nieokreślony wobec skreślenia tego punktu z programu prac IMO.
Introduction
Freeboard was considered long ago as an important element of ship safety. It was recognized that in order to maintain seaworthiness ships must possess some amount of reserve buoyancy, i.e. some volume above the waterplane and below the watertight deck. In a document from the 1st century BC found in
Tuni-sia containing a contract for shipping of goods, the master of a cargo ship sol-emnly promised not to overload the ship. This is probably the oldest reference to freeboard. In the middle ages, the Venetian maritime code required placing the load line mark in the form of an iron cross fixed on the side of the ship [Krap-pinger 1964]. In the second half of eighteen century, Lloyd’s Register recom-mended that the freeboard should be not less than two to inches.
In view of increasing number of casualties at sea and because of the cam-paign of Samuel Plimsoll (1824 – 1899) the British Board of Trade issued the Merchant Shipping Act in 1873 requiring that the load line mark shall be placed on shipside [Alderman 1972]. This mark should be in the form of a disk crossed by horizontal line, the form that with small changes survived until present time. In 1885 Lloyds Register of shipping created Load Lines Committee that devel-oped first freeboard tables and conditions of assignment, which were in use in Great Britain until 1930. They did not differ substantially from those that were adopted by the 1930 LL conference.
1. Load line conventions
International rules regarding freeboard were established by the first load line convention in 1930. This was followed by the second load lines convention adopted in 1966. In 1988, the protocol to this convention was adopted and final-ly revised version of the annex B to this protocol was adopted in 2003.
Review of load lines conventions is shown in the table 1.
1930 Load Lines Convention included requirements on conditions of as-signment of freeboard, mainly related to watertighness and strength of topsides, tables for reckoning required amount of freeboard and weather zones. Freeboard was considered to be a measure of reserve buoyancy and its amount was related to the length of the ship with several corrections taking into account block coef-ficient, depth, position of the deck line, superstructures, trunks and sheer.
At that time, load lines played important part in ascertaining overall level of safety for majority of ships. With the absence of any compulsory requirements concerning stability, subdivision and damage stability (for cargo ships), strength and overall seaworthiness, load line rules were the sole compulsory international requirements assuring safety in seaway.
Table 1 Review of Load Lines Conventions
Przegląd konwencji o liniach ładunkowych Convention Date of adoption Date of entry into force Comments LL 1930 5.07.1930 First LL Convention
LL 1966 5.04.1966 21.07.1968 Second LL Convention. Extension of the freeboard tables bow height, zones Amendments 1966 – 1988 Never Amended conditions of assignment Protocol 1988
to LL 66
1988 3.02.2000 Tacit amendments procedure
Amendments to Annex B to Protocol 1988
2003 01.01.2005 Conditions of assignment amended, new formula for bow height
The development of shipbuilding technology, in particular increase of ship’s size, development of new ship types, e.g. large tankers, caused that in the early sixties of the last century the need for revision of 1930 LL requirements was quite obvious. Under pressure of some governments, IMO organized in 1966 the second International Conference on Load Lines. During this confer-ence doubts were expressed as to the rationale of the principles of reckoning of freeboards. It was stressed, that at that time, contrary to the situation in 1930, there were already adopted or recommended separate requirements concerning stability, subdivision and damage stability and strength of the ship hull (the last ones by classification societies). Some delegates argued, that only reason to maintain load line requirements was the need to protect the deck against green water in heavy seas and in particular to assure safe deck platform for people working on deck. In their opinion, this “deck wetness” principle should replace “reserve buoyancy” principle adopted in the 1930 LL convention. They argued also that tools were already available to calculate deck wetness with sufficient accuracy and referred inter allia to papers published by Newton [1960], Tick [1958], Goodrich [1964] and others.
The idea of estimating freeboard based on deck wetness principle was in general accepted by the 1966 LL conference, but practical realization of this task was impossible in the short time available during the conference. Therefore, finally the old principle of reserve buoyancy was maintained. Freeboard tables were extended to greater ship lengths and, in general, the amount of required freeboard was reduced bearing in mind experience gained. Ship owners and operators who received obvious financial benefit claimed this as a great success
of the conference. The convention was ratified very quickly and came into force approximately two years afterwards.
Several amendments to the 1966 LL convention were adopted by IMO after 1968, but they never came into force because of the very cumbersome procedure of adoption of amendments to the convention. Because of that, in 1988 IMO adopted Protocol to the convention, the most important part of it being introduc-tion of the tacit amendments procedure. According to this procedure, amend-ment came into force automatically after one year (or any other period specified) unless there are a definite number of objections. Introduction of this procedure accelerated substantially coming into force regulations developed by IMO.
2. 2000 Load Lines Convention
After the 1966 LL convention came into force, the shipping world was so happy with the new freeboard tables that the idea of developing new freeboard tables based on the deck wetness principle was forgotten for almost twenty years. Only in mid-eighties, some countries (Argentina, China) raised the point that 1966 LL conference agreed in principle that freeboard tables should be developed based on deck wetness and that there is time to review freeboard ta-bles that were almost hundred years old. IMO took this initiative and included in its work programme the item: “Revision of the technical regulations of the 1966LL Convention”. The work plan for this task was established with the aim of adoption new revised LL Convention in the year 2000.
The reasons for aiming at the revision of the 1966 LL convention were summarised as follows [IMO 1996]:
1. Since 1966 SOLAS 74 and MARPOL conventions have been adopted and a number of amendments to these conventions have been adopted, the requirements of the LL convention should be reviewed to keep the requirements consistent with other conventions.
2. New technology and scientific findings which could not have been ap-plied in 1966 should now be available and could be employed to define the requirements of the LL convention an a more rational manner. 3. New types of ships, e.g. high speed craft have been developed.
4. Recent research indicates that economical benefit for freeboard may be given to larger ships, for example tankers, when new direct calculation methods are applied.
5. Concern for the safety of small ships.
The beginning of this work was very enthusiastic. Several scientific papers were published discussing problems related to freeboard and new approaches to development of freeboard tables based on deck wetness [Alman et al 1992,
Buchner 1995]. In China, Germany, Japan, the Netherlands, Poland and the United States research programmes were established aimed at developing new freeboard tables and bow height formulae based on deck wetness principle. Hundreds of reports were submitted to IMO, and/or published in scientific mag-azines, where results of the investigations were discussed. Few representative reports are quoted below only with the aim to show how enormous amount of work was done: Journeé et al [1997 – 2001], Kobylinski [1995], Stasiak [1999], Meier et al [1996], Zhu Yonge et al [1996, 1998], Takaki et al [1993], IMO [1991], Sucharski [1996].
The established working group elaborated work programme and accepted the general framework of the future convention proposed by polish delegation [Kobylinski 1995]. This framework is shown in the figure 1.
Fig 1. Proposed framework of the 2000 LL Convention Rys.1. Proponowany układ konwencji LL 2000
The most important feature of this framework is the possibility to apply optional direct method of estimating freeboard using deck wetness principle. This method might be used, subject to the decision of Administration, first to novel ship types. According to this framework freeboard tables (or formulae) should be elaborated also using deck wetness principle.
Conventional ships
Non-conventional
ships High speed craft
SOLAS HSC
Code
Freeboard
tables Direct method
Freeboard
tables Direct method
Conditions of assignment
Assignment of Freeboard CERTIFICATE
Apart from the basic problem of amending freeboard tables, the working group made a great effort to revise the text of regulations 1 to 26 containing conditions of assignment. This part of convention really needed revising be-cause of progress in ship design. Many amendments to this part were already adopted by IMO, but they never came into force. In addition, there were many necessary interpretations developed by IACS and some LL Circulars issued by IMO. All these should be incorporated in the proposed revised text of technical regulations of the convention.
3. Change of approach to load lines regulations
In the course of preparation of the 2000 LL Convention the initial enthusi-asm vanished. Studies of the relation between deck wetness and freeboard showed that using this principle freeboard would not be lower than prescribed by 1966 tables, and for smaller ships should be even higher. This was one rea-son for lost of motivation. U.S. delegation expressed this view expressis verbis. Other reason of losing interest in changing freeboard tables were difficulties in finding proper expression for freeboard as a function of ship parameters based on protection against excessive deck wetness. There were also many problems to be solved when deck wetness principle would be used, such as proper as-sumption regarding climatology, acceptable deck wetness criteria, effect of bow flare and non-linear approaches. These problems are not discussed here, but they might need more time to solve.
On 3.02.2000 Protocol to the 1966 LL Convention came into force and since then accelerated amendments procedure was possible. Under pressure of higher IMO bodies, this opportunity was used to change approach to the idea of convening new convention. It was decided that revised text of technical regula-tions should be developed as amendments to the Annex B of the 1988 LL Proto-col. Annex B contained original text of the technical regulations of the 1966 LL Convention. This procedure created the chance the revised regulations would come into force in short time. With this approach, however, only first part of the LL convention, regulations 1 to 26, could be amended and the revision of free-board tables was left for the future consideration because this part of the task was not completed at that time.
The majority of the SLF sub-committee agreed with this initiative and the amended Annex B was adopted in 2003 and eventually came into force on 01.01.2005.
4. The future of the LL Convention
The adoption of the Revised Annex B to the 1988 Protocol to the 1966 LL Convention was clamed as a great success. In fact, conditions of assignment (regulations 10 to 26) were completely re-drafted and brought to modern stand-ards. All inaccuracies and vagueness were cleared. New bow height formula was included.
After the decision to adopt amendments to Annex B of the 1988 Protocol had been taken, the SLF sub-committee considered possibility of development revised freeboard tables based on deck wetness concept in the future within a long-term project. This was in principle agreed in the beginning. However there was a vague discussion during next two sessions of the sub-committee and apparently there was no motivation to revise freeboard tables and delegations lost interest in further work. Several objections with regard continuation of the work were raised and the rationale to use deck wetness concept was questioned. Some delegations expressed the view that the old principle of reserve buoyancy should be kept. Eventually, with little support for continuation of revision of freeboard tables at the 48 session of the sub-committee in 2005 the item on revision of technical regulations of the LL Convention was deleted from the work programme.
5. Success or failure?
Basic freeboard tables are now more than hundred years old. In 1966 they were extended to greater ship lengths and the required values of freeboard slightly reduced for larger ships. Hundred years ago or even seventy years ago (if we take the date of the first LL Convention) significance of freeboard was completely different as it is now. The technical environment was different, ships were different, and approach to safety at sea was different. With the absence of other safety requirements freeboard regulations were one of the most important factors contributing to ship safety. This was properly understood during the 1966 LL conference, where the technical committee of the conference discussed during the first two weeks possibility of developing freeboard tables based on the deck wetness concept.
It was recognized then, as it was recognized during recent discussions in SLF Sub-committee, that freeboard tables require revising. For example, correc-tion for block coefficient works in the wrong direccorrec-tion. More important, model tests and studies of the effect of green water coming on deck in heavy seas (e.g. Buchner [1995], Ogawa et al [2000], Kapsenberg & de Kat [2000]), re-vealed that loads exerted on deck structures and hatch covers are much larger than assumed in the LL Convention. The rupture of the cover of hatch No.1
during typhoon ORCHID was probably the primary cause of the bulk carrier DERBYSHIRE disaster [Faulkner & Williams 1995]. This point was partially taken into account with the new bow height formula based on the deck wetness principle requiring higher bow height, however model tests mentioned above did clearly show that this is not sufficient.
There is also the matter of smaller ships, under 150m in length. All studies performed during the preparation of the new regulations revealed, that in order to maintain the same level of safety from the point of view of deck wetness smaller ships should be assigned higher freeboard than required by the existing freeboard tables. It means that the level of safety for small ships is actually smaller than for large ships. This conclusion was ignored in the new rules.
It was stressed during the discussions that there are some other regulations that indirectly may require higher freeboard than prescribed in the LL Conven-tion. Intact stability, strength considerations and in particular damage stability regulations usually could be satisfied only with the freeboard larger than calcu-lated according to freeboard tables. Therefore, maintaining safe working plat-form is the solely purpose of LL Convention.
The success of the new LL regulations is obviously new part on conditions of assignment. This part for the long time required reviewing. This purpose has been achieved. However, in the opinion of the author, the initial aim of review of the technical regulations including freeboard tables has not been achieved. Only small part of it consisting of developing of the new bow height formula based on deck wetness concept was in fact included in new regulations. Moreo-ver, with the deletion of this item from the IMO programme the future revision of the convention is now postponed to the unspecified date. There is clearly no motivation to continue this work. The side effect is that tremendous amount of work on developing freeboard tables based on deck wetness principle has been wasted.
There is still another problem related to the LL Convention. The first part of the convention and in particular conditions of assignment is more or less re-peated, although with some differences, in the SOLAS convention Chapter II-1. It would be natural to merge these two conventions into one, avoiding repeti-tions. This idea was considered at IMO in early seventies, officially was pro-posed in 1994 by the UK delegation [IMO 1994]. However, after short discus-sion this idea was abandoned on legal reasons. In the opinion of the author this would be a sound solution and at some time in the future IMO should come back to use this idea in spite of some legal difficulties (different countries ratified LL convention and different SOLAS Convention).
In the opinion of the author, as it is seen from the above, new load line rules adopted as amendments to the Annex B to the 1988 Protocol to 1966 Load Lines Convention should be judged as a failure. With one exception, they neither
failed to introduce deck wetness concept into freeboard tables nor the idea of merging LL convention with SOLAS was realized. Safety level assured by the load lines was not changed and obvious deficiencies of the existing method of freeboard calculation were not eliminated. It is true, that new rules introduce order into conditions of assignment which will make work of ship designers and authorities much more effective but this has no influence on the level of safety implied by the rules, which in some cases, as with regard to small ships and deck loads exerted by green water is not sufficient.
Literature
1. Alderman G. (1972), Samuel Plimsoll and the shipping interest, Editors: R. Craig, D. Charles Ltd. Newton Abbot.
2. Alman P., Cleary Jr. W.A., Dyer M.G., Paulling J.R., Salvesen N. (1992), The international Load Convention: cross road to the future, Marine Tech-nology, June.
3. Buchner B.(1995), On the impact of green water loading on ship and off-shore unit design, PRADS’95, Seul.
4. Faulkner D., Williams R.A. (1995), M.V. DERBYSHIRE – search assess-ment and survey. M.V.DERBYSHIRE colloquium, RINA, London.
5. Goodrich G.J. (1964), The influence of freeboard on deck wetness, NPL Report 60, November.
6. IMO (1991), Proposal on revision of minimum bow height of 1966LL con-vention and report on study of freeboard of small ships under 1966 ICLL, Submitted by China, Doc. SLF 35/7/3.
7. IMO. (1994), Proposal to transfer the 1966 Load Line Convention into SOLAS, Submitted by the United Kingdom, Doc. SLF 38/8/2.
8. IMO (1996), Revision of technical regulations of the 1966 LL convention, Report of the working group, Doc. SLF 40/WP.4.
9. Journeé J.M.J, Zhu Yonge, de Kat J.O, Vermeer H.(2001), Joint develop-ment of a bow height formula by China and the Netherlands based on prob-abilistic deck wetness analysis, Delft University of Technology, Technical Report 1270-P, DUT.
10. Journeé J.M.J., de Kat J.O., Vermeer H. (1997, 1998, 2000, 2001), Com-parative Load Line calculations, Part I, II ,III, IV, V, VI & VII, Delft Uni-versity of Technology, Technical Reports 1078-P, 1099-P, 1159-P, 1222-P, 1226-P.
11. Kobyliński L. (1995), Freeboard calculation – traditional and future ap-proach, Marine Technology and Transportation, Computation Mechanics Publications, Southhampton.
12. Krappinger O. (1964), Freibord and Freibordvorschriften, Jahrbnuch der STG, s. 232.
13. Meier H., Ostergaard C. (1996), Zur direkten Berechnung des Freibordes fuer den Schiffentwurf, Jahrbuch der STG, Bd., s. 254.
14. Newton R.N. (1960), Wetness related to freeboard and flare, Traansactions RINA, Vol p. 49.
15. Ogawa Y., Taguchi H., Ishida S. (2000), A prediction method for the ship-ping water height and its load on deck, Osaka Seakeeship-ping Symposium. 16. Stasiak J. (1999), Metody wyznaczania bezpiecznej, ze względu na
zalewa-nie pokładu, wolnej burty statków morskich. Sprawozdazalewa-nie z realizacji pro-jektu badawczego Nr. 9 T12 C031 12, Politechnika Gdańska, Katedra Hy-dromechaniki Okrętu.
17. Sucharski D. (1996), Freeboard assignment, SNAME Load Lines ad hoc Panel.
18. Takaki M., Takaishi Y. (1993), Development of expression for estimating bow freeboard and assessment of the 1966 Load Line Convention, Japan Society of Naval Architects.
19. Tick L.J. (1958), Certain probabilities associated with bow submergence and ship slamming in irregular seas, Journal of Ship Research, June. 20. Zhu Yonge, Chen Guoquan, Lu Deming (1996, 1998), Study on reviewing
freeboards of ICLL, China Classification Society Technical Reports 1 – 9. Shanghai Rules and Research Institute.
Wpłynęło do redakcji w lutym 2006 r. Recenzent
prof. dr hab. inż. Bernard Wiśniewski Adres Autora
prof. dr. hab. Lech Kobyliński
Fundacja Bezpieczeństwa Żeglugi i Ochrony Środowiska 80-278 Gdańsk, ul. Chrzanowskiego 36
