THE EUROPEAN PASSENGER CAR FERRY FLEET REVIEW OF DESIGN FEATURES AND STABILITY CHARACTERISTICS OF PRE- AND POST SOLAS 90 RO-RO PASSENGER SHIPS

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1 1 THE EUROPEAN PASSENGER CAR FERRY FLEET REVIEW OF DESIGN FEATURES AND STABILITY CHARACTERISTICS OF PRE- AND POST SOLAS 9 RO-RO PASSENGER SHIPS Apostolos Papanikolaou, Professor, Head of Ship Design Laboratory, National Technical University of Athens, papa@deslab.ntua.gr Eleftheria Eliopoulou, Dipl.-Eng., Dr.-Eng. Cand., Ship Design Laboratory, National Technical University of Athens, eli@deslab.ntua.gr SUMMARY This paper presents an analysis of systematically collected technical data of Ro-Ro Passenger ships operating mainly in European waters. The data were derived from collaborative work within the EUprojects SAFER-EURORO [1] and ROROPROB [2] as well as from independent work of NTUA-SDL. The developed technical database enables a systematic analysis of collected data and a variety of conclusions on past, presently adopted and foreseeable practices in Ro-Ro Passenger Ship Design pertaining to various main ship characteristics, with emphasis on ship stability and safety. 1. INTRODUCTION The Ro-Ro concept is a very popular and efficient mode of transportation especially in Europe, where 5% of the world s Ro-Ro shipping fleet operates. From the economical point of view, the capability of carrying simultaneously a wide variety of cargoes with minimum infrastructure and shore-based equipment make the particular ship type most competitive. In terms of safety/stability, the vulnerability of large vehicle spaces creates a serious stability and floatability problem in case of flooding due to collision or other incidents leading to car deck flooding (e.g., bow door opening). A significant part of the presented work is within the scope of the EU funded project ROROPROB [2], aiming at developing and implementing a new formalized design methodology for optimal subdivision of Ro-Ro Passenger ships based on the probabilistic damage stability approach. 2. TECHNICAL DATABASE The present RORO Technical Database serves as a comprehensive and stand-alone reference of European Ro-Ro Passenger Ferry fleet of unique technical content and extent of collected data. It currently includes data of 78 European ships of the following types: Passenger/Car Ferries, Passenger/Train/Car Ferries, Vehicle Carriers, Ro-Ro Cargo ships. With respect to the Passenger/Car Ferries, the database is considered to be fully representative of the present status of the entire European Passenger/Car ferry fleet. 2.1 DATABASE STRUCTURE The database has been developed under MS Access 2. The registered data refer to available information on the following ship characteristics:!"general characteristics of the vessels (name, former names, owner, flag, area of operation, class, crew, builders, year of build, year of major modifications).

2 2!"Main technical characteristics, such as main dimensions, lightship weight, displacement and payload, powering, life saving equipment.!"special devices such as: propellers, rudders, thrusters, stabilizers, sponsons, stern/bow doors.!"information on intact stability and loading conditions.!"basic subdivision below and above main car deck.!"damage stability information on worst case (equilibrium and values of residual stability)!"stability standard currently in compliance as well as the next relevant regulation to be in compliance.!"severe Casualties Records.!"Outline of general arrangement. 2.2 DATABASE ANALYSIS The following analysis has been carried out with respect to category Ro-Ro Passenger/Car Ferries and attempts to relate technical and global economic ship characteristics to their stability and eventually safety. The sample of analysed data contains 498 ships and is given in Table 1. Average Min - Max Sample Length Over All m Length Between Perpendiculars m Breadth Moulded m Depth to the Main Deck m Draught m Deadweight t Lightship t Displacement t Gross Register Tonnes Speed kn Total Power of Main Engines HP Year of Built Year of Mod/cation of Major Char Table 1: Sample of analysed Passenger/Car Ferry data For the study, a major breakdown into two main categories has been considered, namely: sample of ships built before 199 and ships built after 199, Figure 1. This breakdown was essential, firstly because of the change of design philosophy in the last decade and secondly because of the request for compliance with higher stability standards after the introduction of SOLAS 9. Further categorizations have been also considered such as: ships built after 1993 or 1997, in order to have more clearly the possible effect of the SOLAS 9 and SOLAS 95 requirements and of more recent technological developments. Note however, that in some of these category cases, the differences are not significant, compared to the overall post-199 results. Additionally, in some other cases, the sample data are not considered satisfactory, due the limited number of registered ships in those categories, in order to conclude with certainty. Finally, the analysis of data considers a categorisation with respect to the different stability standard in compliance for the entire sample of registered ships.

3 3 post % % Sample of 497 ships % pre % 3. REVIEW OF RESULTS 3.1 SIZE OF VESSELS Figure 1: Distribution of sample acc. to Year of Built The last decade has witnessed a continuous increase of the size of vessels and additionally higher service speeds and powering requirements, leading to a new generation of Ro-Ro Passenger Ferry designs and reflecting the increasing demand for faster, more comfortable and safer sea transport, Figure 2 and Figure 3. pre pre 199 post 199 post 1993 post 1997 pre 199 post 199 post 1993 post 1997 meters, knots Loa Loa Lbp Lbp Breadth Dmain Draught Speed tonnes, RT, HP DWT LS Displ. GT Power Figure 2: Averages of main dimensions and speed Figure 3: Mean weights, tonnage & powering 3.2 DIMENSIONAL RATIOS & COEFFICIENTS!"L/B ratio: there is no clear trend of the particular ratio. Analysis based on different Lbp categorisation indicates that the ratio decreases for ships built post-199, especially in the range of Lbp up to 16m. This reflects the relative increase of beam for achieving the enhanced stability standards. On the other hand, length is a major parameter greatly affecting the building cost, but it also depends on harbour and route limitations.

4 4 L/B Ships of Lbp Ships of Lbp Ships of Lbp 1-13m 13-16m >16m Pre Post Ships Built Ships Built Ships Built L/B post 1993 post 1997 post Vs !"B/T ratio: Clearly increasing for the new vessels, an indication of increased stability requirements. Draft remains constant or slightly decreasing (shallower ships) for enabling docking of large ferries at existing port infrastructure and accounting for restricted draft routings. B/T Ships of Lbp Ships of Lbp Ships of Lbp <13m 13-16m >16m Pre Post Ships Built Ships Built Ships Built B/T post 1993 post 1997 post Vs !"T/D ratio: The T/D ratio is of particular importance for the damage stability, because of its direct relation to the ship s intact (and damage) freeboard. It is notable that this ratio obviously decreased (indicating increased freeboard), Figure 4. Ships built with enhanced stability standard have a T/D ratio within the range of Regarding ships that are modified to comply with the enhanced regulations, i.e. SOLAS 9+WOD, high T/D ratios are due to external or/and internal modifications such as sponsons, ducktails, barriers, etc. All Ships SOLAS 9+WOD, modified Linear (SOLAS 9 std, F=.5) SOLAS 9 std, F=.5 Linear (All Ships) T/D Lbp (m) Figure 4: T/D ratio acc. to stability standard!"block Coefficient: typically increased, in the average, indicating increased hull form efficiency in terms of space and floatability requirements, Figure 5. Regarding pre-199 results, there is a wide spread of the analysed data, Figure 6. Displacement (t) Ships post-199 y = x R 2 =.9841 Ships pre-199 Ships post-199 Linear (Ships pre- 199) Linear (Ships post- y = All -.731x Vessels + w/o.6964 spns-(1) R 2 =.426 Alexander's Formula (k1=1,8) A. Papanikolaou, E. Eliopoulou, The European 199) Passenger Car Ferry.4 Fleet Review of Design Features And Stability V(kn)/[L(ft)].5 LBT/1 Cb Alexander's Formula (k2=1,5) Ships Built after 199 Linear (Alexander's Formula (k1=1,8)) Linear (Alexander's Formula (k2=1,5)) Linear (All Vessels w/o spns-(1)) Linear (Ships Built after 199) Alexander's (k1) y = -.5x Alexander's (k2) y = -.5x + 1.5

5 5 Figure 5: Displacement vs. (LBT/1) Figure 6: Cb vs. V/ L With respect to the minimum values of block coefficients, a notable point is that some registered values of abt..45 for some older ships now disappeared. Ships Built Ships Built Ships Built Cb post 1993 post 1997 post Vs !"Powering and related coefficients: The coefficient of the English Admiralty, Cn, reflects the hydrodynamic efficiency of the ship s hull form. It can be noted that vessels built post-199 have improved hydrodynamic efficiency, Figure 7, despite the fact that operational speeds (Froude numbers) and the block coefficients are in the average higher. For ships built post-1993, Cn varies as indicated in the next table. Power (HP) Ships Built Ships Built Ships Built Cn post 1993 post 1997 post Vs For a given speed, the required horsepower per ton displacement of newer ships is less than for the older ones, Figure Ships built pre-199 Linear (Ships built pre-199) Ships pre-199 y =.43x R 2 =.8234 Ships post-199 y =.37x R 2 = Δ 2/3 * V 3 Ships built post-199 Linear (Ships built post-199) Power (HP)/Displaceme Pre-199 (Vs<24 kns) Ships with Vs>=24 Kns Expon. (Post-199 (Vs <24 kns)) Speed (kns) Post-199 (Vs <24 kns) Linear (Pre-199 (Vs<24 kns)) Poly. (Ships with Vs>=24 Kns) Figure 7: Power vs. [(Displacement 2/3 * Speed 3 ) Figure 8: (Power/Displacement) vs. Speed Figure 9 shows the installed main engines horsepower per passenger for ships carrying more than 1 passengers y = x R 2 =.867 HP/Pass Pass >1 Pass >1 (post 199) Linear (Pass >1 (post 199)) Speed (knots)

6 6 Figure 9: HP/Passengers vs. Speed 3.3 MAIN DIMENSIONS For the estimation of the main dimensions in the conceptual design stage, some formulae were deduced by regression analysis of the collected relevant data, Figures 1 and 11. Bmld (m) All Vessels y =.6775x.7142 R 2 =.861 All Vessels Ships Built after 199 Power (All Vessels) Power (Ships Built after 199) 15 1 Ships post-199 y =.9245x.6544 R 2 = Lbp (m) Depth (m) All Vessels Ships Built after 199 Power (All Vessels) Log. (Ships Built after 199) 11 All Vessels 1 y =.2746x R 2 = Ships post y = Ln(x) R 2 = Lbp (m) Figure 1: Main Dimensions vs. Lbp Draught (m) All Vessels Ships Built after 199 Linear (All Vessels) Power (Ships Built after 199) All Vessels y =.29x R 2 = Ships post y =.2758x R 2 = Lbp (m) Displacement (t) All Vessels Ships Built after 199 Power (All Vessels) Power (Ships Built after 199) All Vessels y =.64x R 2 =.9377 Ships post-199 y =.992x R 2 = Lbp (m) 3.4 DISTRIBUTION OF WEIGHTS Figure 11: Draught, Displacement vs. Lbp Lightship Weight & DWT: For given main dimensions, a vessel built pre-199 appears to dispose a larger weight of lightship compared to the newer ones. Focusing on the post-199 ships, lightship is increasing for post-1997 in comparison to ships built in , Figure 12. From another point of view, the required compartmentation to meet higher stability standards, leads to an increase of lightship weight due to the additional structural weight, proportional to the number of fitted bulkheads, Papanikolaou et al (2), Figure 13. Ships pre-199 Ships Ships post-1997 Power (Ships pre-199) Power (Ships ) Linear (Ships post-1997) Ships with lower hold 2 18 A. Papanikolaou, E. Eliopoulou, The European Passenger Car Ferry Fleet Review of Design Features And Stability Characteristics 14 Of Pre- and Post SOLAS 9 Ro-Ro Passenger Ships, 12 pre-1993 Euroconference on Passenger Ship Design, Lightship (t) LS (t) 14 post Linear (pre-1993) 9 Linear (post-1993)

7 7 Figure 12: Lightship vs. LBDu/1 Figure 13: Lightship vs. # of basic transverse watertight compartments The DWT/Δ ratio vs. DWT and speed as parameter is presented in Figure 14. Commenting on this figure it should be remembered that vessel speeds continuously increased, leading to an increase of powering and related machinery weights. However, some increase of machinery weights could be counterbalanced though the introduction of novel machinery units of reduced weight per installed HP. Ships with Vs>2 kns Ships with Vs<=15 kns Linear (Ships with Vs>2 kns) Ships with Vs>=24 Kns Ships with Vs=15-2 kns Linear (Ships with Vs=15-2 kns) DWT/Δ DWT (t) 3.5 PAYLOAD Figure 14: DWT/Displacement vs. DWT Lanes length/lbp ratio: The ratio of the car lanes Length/Lbp has significantly increased for the newer ships, indicating the higher efficiency of modern designs. Vessels built before the year 199 dispose an average ratio of 7.3, whereas those built after 199 have a 6% higher ratio of For a given deck waterplane area, ships post-199 can accommodate a larger number of lane meters than the older ones, Figure 15. In domestic, coastal voyages, service speeds have been kept at normal levels because it is either impossible by environmental conditions or non-economical to take full advantage of the higher service speeds, Figure 16. Lanes Length (m) All Vessels Ships Built after 199 cruise type Power (All Vessels) Power (Ships Built after 199) Ships Built after 199 y =.936x R 2 = Lbp * Bmld Speed (Kns) HP/Passengers Short International International Domestic Linear (Short International) Linear (International)

8 8 Figure 15: Lanes Length vs. Lbp * Bmld Figure 16: HP/Passengers vs. Speed, per voyage type 3.6 COMPARTMENTATION BELOW MAIN CAR DECK The introduction of the longitudinal bulkhead concept inside the B/5 line has changed thoroughly the philosophy of design of the internal compartmentation below the main car deck. As a result, the considerable floodable volumes below car deck have been reduced, especially for shallow damages. The majority of older ships have only transverse bulkheads (TB), as a standard subdivision, to the greater extent of their length, though in newer ships the combination of transverse and longitudinal bulkheads (LB&TB) is a common feature, except for the relatively small ships, Figure 17. Number of ships TB Type of design LB&TB Older Ships Newer Ships # of watertight compartment Length (m) All Ships SOLAS 9 SOLAS 9+WOD by modifications Linear (All Ships) Linear (SOLAS 9) Linear (SOLAS 9+WOD by modifications) Figure 17: Distribution of type of internal compartmentation below main car deck Figure 18: Number of watertight compartment vs. Length The length of primary transverse watertight compartments has been reduced for the newbuildings (and accordingly the number of WT compartments increased) to meet the higher damage stability standards, Figure 18. In order to utilise the space below the main car deck, as this space cannot be used for accommodation purposes by the latest SOLAS regulations, large lower hold decks inside B/5 line are adopted in new concepts, that in some cases might be exceeding even 5% of ship s length, Figure All Vessels Ships built post1993 LLowerHold/Lbp LLowerHold (m) Older Ships Newer Ships Linear (Older Ships) Linear (Newer Ships) Length of Main E.R.(m) Power (HP) Figure 19: Lower hold Length/Lbp vs. Lower hold Length Figure 2: Length of Engine Room vs. installed power

9 9 Although these large non-divided spaces under main car deck are considered intact in typical SOLAS damage conditions, there might be the cause of serious stability problems in cases of actual penetration beyond B/5, if not properly arranged. The length of engine room appears to become shorter, for given installed power, Figure 2. This is attributed to the consideration of novel machinery arrangements and the use of more compact machinery units. 3.7 INTACT STABILITY Freeboard is an essential parameter affecting the stability and safety of ships both in intact and damage condition. A comparison of the intact freeboards between vessels of different stability standard shows that SOLAS 9 2-compartment standard and A.265 ships dispose comparable and in general larger intact freeboard heights, Figure SOLAS SOLAS 6 FB (m) Modified as 9+WOD 9/92 74 SOLAS 9/92, F=.5 A. 265 SOLAS 74/*, SOLAS 88 FB acc. To ILLC Ships modif. 9+WOD Linear (SOLAS 74) Linear (SOLAS 9/92, F=.5) Linear (SOLAS 6) Lbp (m) Linear (FB acc. To ILLC) Linear (Ships modif. 9+WOD) Figure 21: Intact Freeboard vs. Lbp Note that intact freeboards for the larger new ships are close to and over 2.5 m, what clearly calls for the provision of new docking facilities in some European ports, currently adjusted to freeboards in the range of 1.5 to 2.m. Enhanced stability standards clearly require greater GM values, Figure 22. This should generally affect ship s sea kindness, as ships become stiffer in roll and passengers might experience higher transverse accelerations. However, this negative effect of GMt on seakeeping is commonly counteracted by the employment of stabilising fins and of antirolling tanks. GMt versus Breadth/FB GMt (m) Breadth/FB Intact Condition All Ships SOLAS 9 std SOLAS 9+, modified Linear (All Ships)

10 1 Figure 22: Intact GM vs. Breadth/Intact Freeboard 3.8 DAMAGE STABILITY Newer vessels have obviously improved damage stability characteristics due to their compliance with the enhanced damage stability criteria of SOLAS 9 and SOLAS 9+WOD, Figure 23. GMres (m) Lbp SOLAS9 SOLAS 74-6 SOLAS9+WOD, sponsons Linear (SOLAS9) Linear (SOLAS 74-6) Figure 23: Distribution of residual values of GM 3.9 POSSIBLE IMPACT OF STOCKHOLM AGREEMENT TO SHIPS OPERATING IN SOUTH EUROPEAN WATERS A dedicated study on the possible impact of the Regional Stockholm Agreement (SOLAS 9+WOD) on ships operating in South European waters has been recently carried out jointly by Ship Stability Research Centre University of Strathclyde and the Ship Design Laboratory National Technical University of Athens [4]. The objective of the particular study was, among others, to establish which ships operating in EU waters not covered by the Stockholm Agreement need to be upgraded to comply with the provisions of Stockholm Agreement and the possible extent of required modifications. The NTUA-SDL Technical Database was used to identify all affected vessels operating in EU waters along with their relevant technical details. Based on the inventory of the ships under investigation, their current stability standard of compliance, area of operation (typical operational significant wave height Hs) and corresponding subdivision index A/Amax values, it was concluded, that the techno-economical effort for the affected ships to be upgraded to SOLAS 9, two compartment standard will not much deviate from the effort to formally comply with the provisions of the Stockholm Agreement.

11 11 In Tables 2, 3 the number of affected South European ships (SEU) and the anticipated dates of compliance are presented. Regulation 8-1 Oct 1998 Oct 2 Oct 22 Oct 24 Oct ships Not Affected 19 ships F = ships F = ships F = ships F = Total ships affected Table 2: SEU ships-compliance with Regulation 8-1 Regulation 8-2 Oct 26 Oct 28 Oct 21 Oct 211 Oct ships affected Table 3: SEU ships-compliance with Regulation 8-2 The total modification cost for the whole South European fleet was estimated to range between a minimum of 16,325 k EURO and a maximum of 249,722 k EURO, depending on the finally adopted modification option (sponsons, ducktails, casings, buoyant tanks, cross-flooding, additional subdivisions and internal barriers on car deck, etc.). 4 HELLENIC FLEET Focusing on the characteristics of the Hellenic Fleet (national and international voyages), a significant improvement regarding the renewal of ships can be observed, Figure 24. Considering the data of year 21, the average age of the Hellenic fleet has been reduced to 21 years, being practically today identical to the average age of the entire European Passenger Car Ferry Fleet, Table 1. % of Fleet Hellas up to 5 years Hellas-21 Hellenic PCF Fleet Average of Year of Built (2) = 1977 (98 ships) Average of Year of Built (21) = 198 (17 ships) 6-1 years years 16-2 years years >=26 years years 13% >=26 years 26% 16-2 years % Hellenic Fleet - International Voyages Distribution of Age years 6% 6-1 years 13% Average of Year of Built = 1989 up to 5 years 42% Sample of 31 ships Figure 24: Distribution of Hellenic PCF Fleet Figure 25: Distribution of Year of Built- International Voyages

12 12 Note that according to relevant Hellenic Law, the upper limit of age for Ro-Ro Passenger ships operating in Hellenic waters (domestic voyages) was until very recently 35 years. However this limit was recently reduced to 3 years with an expected significant impact on the existing domestic fleet in the years to come. Regarding the Hellenic ships operating in international waters, it should be noted that 42% of this part of the Hellenic Fleet has an age of up to 5 years and the overall average age of the Hellenic international fleet is merely 11 years, clearly below the overall European Fleet average, but also below the average age of the North European Fleet, standing at about 17 years acc. to the study [4], Figure 25. About 85% of the Hellenic Fleet has two-compartment standard of subdivision, Figure 26. Regarding the one-compartment standard ships, 9% of them must have already proceeded for upgrade with SOLAS 9, Regulation 8-1, though a significant part, namely 46%, has still time until October 25, Figure 27. These ships must also proceed for compliance with Regulation 8-2 (two-compartment standard) at later dates. Regarding vessels with two-compartment standard of subdivision, 18% of them must have already proceeded to actions for compliance with SOLAS 9 Reg. 8-1 or they must have taken proper action to increase their A/Amax values in order to postpone the dates of compliance. Part of this category of ships, namely 26%, is placed under the EUROSOLAS provisions, Figure 28.??????? Distribution of Factor of Subdivision Hellenic PCF Fleet F=1 15% F=.5 85% Sample of 81 ships Figure 26: Distribution of Factor of Subdivision Hellenic PCF Fleet Distribution of A/Amax (Dates of Compliance), Ships with F=1 Hellenic PCF Fleet Distribution of A/Amax (Dates of Compliance), Ships with F=.5 EURO S O LAS % > 97.5% (25) 46% < 85% (1998) % Sample of 11 ships 85%-9% (2) 9% 9%-95% (22) 27% EURO S O LAS 27% < 85% (1998) Sample of 62 ships 3% 85%-9% (2) 15% 9%-95% (22) 18% 95%-97.5% (24) 18% > 97.5% (25) 26% 95%-97.5% (24) 11% Figure 27: Distribution of A/Amax value, Ships with F=1 Figure 28: Distribution of A/Amax value, Ships with F=.5

13 13 5 CONCLUSIONS Decisions in the early ship design stage strongly depend on the designer s expertise and knowledge from the past, but also on the knowledge of state of the art technological developments. Technical ship data to the extent collected herein in a systematic manner are rare, though considered essential in the conceptual-preliminary design stage, that is the stage in which major technical and economic ship characteristics are determined following the owner s requirements and statement of work. The collected data can be not only exploited in the conceptual design stage, but also for the crosschecking the data of individual designs under consideration. Also, the derived regression formulae might be useful in the set-up of a computer-aided optimisation procedure, as planned in the EU funded ROROPROB project. The present analysis shows significant changes in the design of pre- and post SOLAS 9 ships and also in the demand of passenger shipping market. These changes reflect not only changes in safety policy, leading to stricter safety regulations, but also changes in the shipbuilding technology through innovation. As a result, new ships appear to be safer, at increased efficiency and economy. The enhanced safety requirements and the increased open market demands, especially after the complete lift of the cabotage regulation in some South European countries, including Greece, will accelerate the renewal of the European Ro-Ro passenger ferry fleet and especially of the South European Fleet. 6 ACKNOWLEDGEMENTS The work, presented in this paper, was partly supported by the EU-projects SAFER-EURORO (C.N. BRRT-CT97-515) and ROROPROB (C.N. G3RD-CT-2-3) and the dedicated EU-DG VII study CN B99-B2721-S The authors are solely responsible for opinions expressed in this paper and the European Commission is not responsible for any use of the data appearing herein in any form. 7 REFERENCES 1. SAFER EURORO Ship Design Team, Technical Database of European Ro-Ro Passenger Ship, NTUA-SDL Report, European Community DG XII, Brussels, ROROPROB, NTUA-REP-T1.3.2&3-D9-D1, European Community DG XII, Brussels, Papanikolaou A., Eliopoulou E., Kanerva M., Vassalos D., Konovessis D., Development of a Technical Database for European Passenger Ship, Proc. IMDC 2 Conference, Korea, IMPACT ASSESSMENT OF STOCKHOLM AGREEMENT, SSRC-US & NTUA-SDL Partnership, NTUA-REP-PART B-2, European Community DG VII, CN B99-B2721- S , 2.

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