River-sea tankers, ferryboats and other urgent problems in the reports of Marine engineering Bureau colleagues at the "Bubnov Readings"
On the 23-24.12.2014 science-technical Conference on naval structural mechanics "Bubnov Readings" took place in the Saint-Petersburg State Marine Technical University. The Conference was dedicated to the memory of prof. I.G. Bubnov and 110th anniversary of creating naval structural mechanics department.
The Conference was organized by FSUE "Krylovskiy State Scientific Center" (KSSC), FSBEI HPE "Saint-Petersburg State Marine Technical University" (SPSMTU) and by Central branch of Russian Technical-Science Shipbuilders Society named for academic A.N. Krylov. Organized Committee co-chairmen are: E.M. Appolonov, Sc.Dr., stand-in rector of SPSMTU; A.A. Rodionov, Sc.Dr., Prof., head of Structural Mechanics Faculty of SPSMTU; V.M. Shaposhnikov, Ph.D., head of Strength and Reliability of Constructions Department of KSSC; K.V. Rozhdestvenskiy, Sc.Dr., Prof., Vice-President of Russian Science-Technical Society named for acad. A.N. Krylov. Ph.D., Associate Professor E.A. Shishenin is a Scientific Secretary.
Traditionally "Bubnov Readings" are conducted every ten years. 78 reports concerning actual problems of designing/construction and strength of vessels and marine/sea structure were presented at this conference. More than 100 leading specialists from researching institutes, universities, designing organizations and shipbuilding universities participated in the conference.
Marine Engineering Bureau introduced 14 reports at the conference:
1. Analysis of development of general and local strength criteria for marine vessels taking into consideration Strength Rules created by I.G.Bubnov in 1908. Author is V.V. Kozlyakov.
2. Design line of river-sea oil tankers. Author is G.V. Egorov.
More than 78 tankers are built according to this design line of the Marine Engineering Bureau from 2002 till nowadays.
The main tendency is building cargo vessels with enhanced river function for RF European inland waterways part.
Accepting of main particulars for river-sea vessels is defined by way restrictions, strategy of future shipowner and his position in the market, adherence to some or other transport lines and cargo types. As usually, in contrast to dry cargo vessels, the most interesting decisions for tankers are those that provide the maximal cargo capacity for set conditions.
The analysis of corresponding alternatives has allowed producing a parametric line of river-sea oil tankers that are objectively demanded by Russian shipowners and working out projects of new vessels at Marine Engineering Bureau basing on this parametric line.
This parametric line of projects includes high demand for existing Russian market the following basic classes of river-sea oil tankers (self-propelled and tug-barge train ones):
• "Volgo-Balt Max" type; its dimensions correspond to way restrictions of Volgo-Balt Waterway, mostly to turn radiuses and dimensions of locks' chamber. The maximal available cargo capacity is 5000-6000 tons for characterized river draught 3.60 m. Vessel's dimensions and enhanced manoeuvrability (due to full-turn rudder propellers and bow thruster) provide working at Volga River till Astrakhan port;
• "Volgo-Don Max" type; its dimensions correspond to dimensions of locks' chamber of Volgo-Don Shipping Canal. The maximal available cargo capacity is 4200-5500 tons for characterized river draught 3.60 m; the smallest value is for tug-barge trains with R1 class of RS; the biggest value is for vessels with M-PR 2.5 class of RRR. "Volgo-Don Max" vessels are able to operate at "Volgo-Balt Max" lines;
• "BBC Max" type; its dimensions correspond to way restrictions of Belomorsk-Baltic Canal; the maximal available cargo capacity is 2700-3000 tons for characterized river draught 3.60 m. Operation is foreseen at lines between river ports and Belomorsk port through Belomorsk-Baltic Canal with ability of sailing to White Sea. "BBC Max" vessels are able to operate at "Volgo-Balt Max" and "Volgo-Don Max" lines;
• "Lena" type; its dimensions correspond to way restrictions of Lena River and way restrictions of the way from possible building shipyard till sea entering point (e.g. from Volga shipyards through Volgo-Balt Waterway.
In the borders of main classes there are RS and RRR sub-class variants, such as R1, R2, R2-RSN, R3-RSN, "M-SP", "M-PR" and "O-PR". There are also tug-barge trains for existing pusher tugs of "OT-2000" type pushers and for perspective pusher tugs of smaller length; they may be equipped with "river" or "marine" tractive connections.
Important feature of new projects is excess freeboard for character draught; that allows cargo capacity increasing for port work by accepting minimal freeboard at design stage.
Additionally to vessels of mentioned classes, shipowners are interested in smaller deadweight tankers, which as a rule are intended for bunkering other vessels by fuel oil and lubricating oil (bunker vessel) or by other bulk cargoes (vegetable oil, ethylene glycol, sewage etc.).
Vessels were designed in accordance to RS Rules (10 projects), RRR Rules (7 projects), Polish Register Rules (1 project), Ukrainian Register Rules (1 project).
Projects correspond to the following sailing regions: R2 (6 projects), R2-RSN (3 ones), R3-RSN (3 ones), M-SP (2 ones) and M-PR (5 ones).
5 projects have no longitudinal CL bulkhead (005RST01, RST22, RST22M, RST25 and RST27). All projects have 6 cargo tanks.
9 from 19 projects use full turn rudder propellers as united means of movement and maneuverability providing. All vessels are equipped with 2 FPP in nozzle. Main engines of 9 projects are able to use HFO IFO 180-380. All main engines used at MEB projects are of middle-speed type. Vessels' operational speed is of 10.0-12.5 kn at 85-90% of ME output.
Due to full-turn rudder propellers usage enhanced manoeuvrability in the constrained conditions was provided, cargo zone length was enlarged, ER length was decreased by about 20%, cost and necessary mounting time were reduced as well as expected maintenance and repair cost. All these advantages have brightly influenced in shortening of building term of "Armada" series in Turkey.
Hull construction of 2 projects corresponds to RS Ice2 category (former LU2 or L3 ones), 5 projects corresponds to RS Ice1 category (former LU12 or L4 ones) and 5 other projects corresponds to RRR "Ice 3.0"1 category.
3. Basics of hull design of up-to-date river-sea vessels. Author is G.V. Egorov.
Up-to-date conception of mixes river-sea going vessel (RSV) has been formulated in author's papers in following way: RSV is a transport vessel with full usage of inland waterways dimensions, with maximal block coefficient that allows running ability point of view, with increased cargo capacity at minimal depth, with increased manoeuvrability in the constrained conditions and in the shallow waters, with proved operational reliability of hull structures at optimum metal consumption for the hull.
As development of ideas stated in previously published papers, the following main principles of river-sea vessels designing are offered. These principles are realized and continue to be realized in projects of Marine Engineering Bureau:
• RS class R2 was accepted for vessels and tow-barge trains of RSV type of "Volgo-Don Max" class according to prospective transportation directions and to estimation of probable running time losses due to weather waiting; this class allows sea vessel's operation full year including voyages around the Europe. RRR class O-PR2 was accepted for vessels and tow-barge trains of RSV type of "Volgo Max" class; this class is a minimal one for operation at the Gulf of Finland and Azove Sea at spring-summer season. RRR class M-SP 3.5 was accepted for north companies' vessels; this class allows vessel's operation in the voyages through the Northern Marine Way from Taimyr Peninsula to Chukchi Peninsula at July-September period;
• ice class LU1 (Ice 20 - Ice 30) was accepted for RSV that operate at Azove Sea and Caspian Sea in winter according to the accumulated operational experience. Class Lu1 (Ice 40) was accepted for Siberian companies' vessels to ensure safe returning from the "North Delivery". LU2 was accepted for operations at Baltic Sea in winter. LU2 was accepted for operations for the Port of Archangelsk in winter;
• cargo capacity increasing due to growth of effective height of hull section (application of big continues over deck constructions such as trunk or comings of 3.2 - 3.8 m, Figure 1). Same time expenses in domestic ports are reduce on. All this were done with providing sufficient for the accepted class the overall longitudinal strength without increase of thickness of the overwhelming majority of constructions in comparison with the minimal thickness of RS Rules;
• usage longitudinal framing for deck, sides and bottom at the vessel's middle part (Figure 1) that in conjunction with transverse space increase and simultaneously longitudinal space decrease provides more fully hull's plates participation in the general bending and provides better response for local loadings during mooring operations, passing through canal and locks, provides better appearance keeping;
• keeping thickness of sheathing and shell at minimal ones level in order to minimize steel hull weight and to provide required local strength and steadiness due to rational application of the ordinary and web elements;
• appoint identical, whenever possible, thickness of plates of web and ordinary structure elements and shell for providing equal wear durability;
• design sides and bottoms structures on operational loads, which in majority are considered till now "not design" (contacts to waterside structures, ground, etc.);
• design "smooth" flanges of hull girder with a minimum quantity of technological openings and weld fittings in order to increase in actual fatigue durability, usage rationally executed assemblies of structure element crossing and smooth change of the areas of longitudinal structure elements of the hull through its length;
• excluding structure elements inside cargo tanks of tankers (an external structure of the upper deck and trunk, horizontal corrugated transverse bulkheads).
4. Vessels' "conversion" as method for keeping water transport. Authors are G.V. Egorov, N.V. Avtutov.
New vessels building demands significant investments, resources and bought equipment. On the average, 10 - 25 new vessels are built and put into operation every year. Minimal shipbuilding neediness for Russian water transport industry till 2020 is about 350 cargo vessels and more than 400 auxiliary vessels. There is obvious break between ability of shipyards and fleet neediness
In such crisis periods of our country history (the 20-s, the 40-s of last century) in the first place it was paid attention to renewal and more effective using of existing technical means, including transport.
Not only prolongation of vessel's and her elements resource is essentially important but also alternation of vessel's technical-economic parameters and creation of new opportunities are as well as efficiency increasing due to new quality as a result.
Conversion occupies a special place between significant re-equipment variants. Vessel's conversion means big and, as usual, dimensional modernization of existent vessel that includes vessel's all parts survey as for fully new ones; i.e. with check-up meeting of requirements of International Conventions and Classification Society Rules on the date of survey.
Vessel conversion allows solving problems of significant life terms extending and of safety raising in short terms and with expenses smaller than for usual shipbuilding. Some vessels are morally become out of date long before limiting physical depreciation of their hulls and machinery. And, untimely moral becoming out of date is not (as rule) the result of design or building mistakes. Often it is too early to utilize vessels, and the way out from such problem is a re-equipment or modernization.
Analyzing the concrete examples of vessels' conversion, one may highlight the following main technologic variants:
• changing of vessel principal dimensions with replacement part of her hull by new bigger one (e.g. 005RSD06 and RSD11 dry cargo vessels of "Chelsea" type; RSD08 dry cargo vessel "Ommax"; RSD60 dry cargo vessel "Ediniy"; RST05 and RST26 tankers; CNF06 ferryboat "Avangard"; PV02 passenger vessel "Imperiya");
• Increasing of vessel principal dimensions with help of insertions and fixed outer constructions with usage of all old hull (e.g. CNF03 ferryboats of "Smat" type; CNF09 ferryboat "Slavyanin");
• saving small-worn hull (usually for passengers vessels, with full replacing of "interior" and equipment, also with full rearrangement of compartments (e.g. passenger vessels "Alexander Grin" of PV08 prj. and "Il'ich" of PV06 prj.).
Conversion requires to take into consideration defects accumulated during initial vessel's operation, as follows:
• corrosive and mechanical wearing of hull constructions and welding seams; especially local thinning which are documented badly and aren't taken into consideration in the traditional strength calculations;
• deformations of tank top and inner sides due to contacts with cargo and cargo handling equipment; deformations od sides due to contact with bottom while shallow water, walls of locks and canals, births and ice;
• accumulated fatigue damages in the zones of tension concentration, especially micro-cracks and break of material's crystal structure which cannot be detected during survey;
• available alternation of physical-mechanical properties of material (aging).
On may put attention to available constructive and technologic mistakes that are not documented in the building documentation but may take place during vessel's construction. Mainly this are expanded for vessels built for another classification societies and were not attended for marine operation.
Elements of the earlier operated vessel that are accepted for construction of the new vessel should be subject to faults detection and repairing. After that approval procedure should take in order to check up fulfilment of RRR requirements due to availability technical condition of hull constructions, mechanisms and equipment as well as properties of materials that were used in the earlier operated elements.
Life term reserve or wearing level of the pointed elements are defined by the strength and durability analysis basing on actual states analyze (ultrasonic thickness measurement). Capacity of the restoration works of such constructions are defined according due predicted life term and shipowners' financial ability.
Mostly loaded hull constructions that worked out their fatigue resource are not accepted for usage at conversion. Usage of earlier operated hull constructions are accepted first of all for units that don't participate in the general strength, such as flat and 3D sections placed within 0.3L distance from vessel's perpendiculars, sections or parts of deck-house, other constructions (sides' and inner sides' parts, transverse hull elements etc.).
Mentioned restrictions eliminate usage for new shipbuilding the important constructions that may worked out their fatigue resource but which damages (micro-cracks type) cannot be detected during hull survey.
Not only providing of vessel's and her elements resource is essentially important but also alternation of vessel's technical-economic parameters and creation of new opportunities are as well as efficiency increasing due to new quality as a result.
New quality may be provided due to changing of cargo capacity (volumetric and weight), maximal dimensions, freeboard, hull's strength, power plant capacity, ice strengthening. Such changings forward to alternation of vessel' functions, architect-structural type and operational regions.
A creation of "Chelsea" type series of river-sea dry cargo vessels with deadweight about 6000 tons as a mostly bright example of vessels' construction with usage of elements of existing donor vessels. "Volgo-Don" type river dry cargo vessels (507, 507A, 507Á and 1565 projects) built at 1960s are used as donors. Projects 005RSD06 and RSD11 are based on idea of usage high (3.5 m taking into consideration existing coamings) continuous longitudinal hatch coamings that allow due to significant section height increase to enhance simultaneously standard of general strength of vessel's hull (by 112%!!!), cargo holds' capacity and deadweight in accordance with requirements of International Load Lines Convention.
Existing coamings and previous upper deck were the most loaded elements that worked out their fatigue resource. These elements appear now in the zone closed to the neutral axis of the equivalent beam, so they are excluded from the general hull bending; such situation allows keeping them as hull elements. Inertia moment rise of the high transverse section (while keeping bottom thickness) increased bottom section modulus by 66%.
Light weight of 005RSD06 and RSD11 vessels is by 600-800 tons smaller than prototype vessels had. Lesser life term (15 instead of usual 25) allows don't decreasing general strength while lowering the minimal thickness requirements for many hull elements such as floors, web and ordinary frames (i.e. elements that provide mostly the local strength). Thickness decreasing is compensating by serious corrosion preventing measures (painting within double bottom and double sides). As usually at every vessel of the series about 650 tons of new constructions (new coamings, second deck, forecastle and poop, new deck-house and hatch covers). Besides about 550 tons of existing hull elements must to be replaced according to actual hull state. For information, light weight of "Chelsea-6" is 1850 tons.
Total charges for constructing of single "Chelsea" type 005RSD06 vessel was about 5.2-5.5 million USD in the January, 2008. Charges for hull were 2.4-2.7 million USD, charges for equipment purchase and major repair were 1.8 million USD and builder finishing cost about 1.0 million USD. For information, construction cost of "Heydar Aliev" type 006RSD05 vessel was about 14-15 million USD in 2008.
During conversion not only vessel's overall quality is changed but her elements itself. For example, due to increasing number and capacity of diesel-generators regimes of onboard power plant alternates (they become more safe and economical), new abilities are provided i.e. ballasting time shortens (economy of staying time) and rising capacity of air conditioning (enhancing crew life standard).
It is necessary to understand clearly, that nowadays as before all vessel's life term prolongation schemes are not an alternative of new shipbuilding. These schemes allows providing transport necessity of national economy for nearest 10-15 years; in reality they close gap between lowering transportation rate of the fleet and rising demands of the national economy while financial and industrial resourced are limited.
5. Parametrical Line of Black Sea cargo and cargo-passenger ferryboats (hull design requirements). Authors are G.V. Egorov, I.A. Ilnitskiy, D.V. Chernikov.
6. Operational reliability analysis for hull of dry cargo vessels of 21-88 and 21-89 projects. Authors are G.V. Egorov, A.G. Egorov.
7. Features of creation of new cruise vessel Alexander Grin" using donor vessel's hull. Authors are G.V. Egorov, Ya.V. Kalugin.
8. Features of new concept design for combined "Volgo-Don Max" platform tanker. Authors are G.V. Egorov, V.I. Tonyuk, I.N. Boyko.
9. Principles of hull design of river ferryboats for northern regions of Russia. Authors are G.V. Egorov, V.I. Tonyuk, A.G. Egorov.
10. About summation of different loadings' components acting onto hull constructions. Author is I.F. Davydov.
11. Analysis residual general strength of damaged river-sea tanker's hull. Author is V.A. Nilva.
12. Approximate method of rigidity and strength calculation for elements of frame rings that consist of girder trusses and 3D compartments of single-hold dock type vessels with help of combined beams theory. Author is N.F. Butenko.
13. Estimation of hull weight of river-sea cargo vessels at preliminary design step. Author is A.G. Egorov.
14. Investigation of sailing region influence on hull weight of river-sea tanker. Author is O.G. Egorova.