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27.01.16 13:54
Mixed river-sea integrated vessels and tug-barge combinations for work from Dnepr River to transshipping complexes, marine ports and Danube ports

On 20.01.2015 a Ph.D. work of scientific researcher of Marine Engineering Bureau Alexander Egorov was presented for the Council of National Shipbuilding University named after Admiral Makarov. Title of the work is: "Choice of optimal characteristics of river-sea integrated vessels and tug-barge combinations".
Presentation materials can be downloaded here (Adobe PDF, 16 MB).
Here below theses of the work are given:
1. Since 2014, strong interest concerning the most effective mixed river-sea vessels (RSV) for the Dnepr River region is observed; reason is sharply increasing of cargo flows, generally due to export grain transportations.
Situation in the market of marine and river transportations is ambiguous, but there are prospects for freight traffics growth both for Danube River and Dnepr River. In relation to the Dnepr River region, it is possible to expect increase of cargo flow due to transfer of part of railway and car-train transportation to more economic and ecologically safe water transport. Upon transition of the rolling stock to private structures and control strengthening for weight load on axis for cars, it is necessary to expect tariff increase for cargo transportation; that should positively influence onto competitiveness of a water transport.
The analysis of technical condition shows that further operation of old river and river-sea vessels concerns with considerable risks (failure of vessel's equipment, mechanisms, a leakage through outer shell, hull deformation and many other situations which can lead both to environmental disaster and to perish of vessel and crew). Therefore in the next years we may expect mass discarding of vessels which age exceeds 40 years.
New modern vessels are required in order to satisfy transportation demands for directions Dnepr River - Black Sea - Danube River, Dnepr River - Black Sea, Danube River - Black Sea. These new vessels are RSV including tug-barge combinations (TBC) and integrated vessels (IV), which are the mostly economic favourable variant inn case of stable cargo flow and the adjusted logistic chain in ports at loading/unloading, especially when water depth is limited.
2. Modern new generation RSV (including integrated ones) differ from Soviet times analogues by enhanced capacity of cargo holds/tanks due to block coefficient (Cb) increasing and usage of high over-deck constructions (coamings or trunks). They have more powerful main engines for providing safe navigation in seas in accordance with accepted class. All this requires corresponding analysis and justification.
Earlier Prof. G.V. Egorov has demonstrated that for new generation RSV accepting of main particulars is fully determines by way restrictions. In spite of clear way restrictions, in Soviet times the approaches to design of restricted navigation region vessels were close to standard (marine) scheme of main particulars defining. That is why analysis of operational restrictions is of principal interest for accepting main particulars of IV (TBC).
A Mater complex graduated work "New fleet creation for cargo transportation from Dnepr River to Danube River" was carried out by group of students (including author) in the Odessa National Marine University under the guidance of S.N. Baskakov. Calculations showed that vessels that fully use way restrictions are mostly effective for mass transportation through the line Dnepr River - Danube River.
Yu.A. Kochnev prepared Ph.D. work under the guidance of E.P. Ronnov at the Volga State University of Water Transport; conclusion about necessity of accepting main particulars maximum available for discussed line is confirmed in this work.
Optimization problem for main particulars definition is the main problem for initial design stage; stable attention was paid at it in soviet times (V.M. Pashin) as well as just know (M.V. Voyloshnikov, V.A. Nekrasov, N.A. Efremov and others). Definition and optimization of main particulars of river vessels (RV) and RSV are described in papers issued by A.F. Videtckiy, A.B. Karpov, Yu.A. Kochnev, E.P. Ronnov, B.V. Bogdanov, G.I. Vaganov, E.R. Ratner, B.M. Sakhnovskiy, N.A. Taranukha, Marine Engineering Bureau (under leadership of G.V. Egorov), National Shipbuilding University named after admiral Makarov (V.A. Nekrasov, O.I. Solomentsev, A.V. Bondarenko, A.N. Vashedchenko and others).
Formulae and ideas proposed by these authors don't take into account today realities, such as: tendencies to increase "fatness" on new TBC and IV (resistance increasing); changings in the Regulations of Classification Societies, appearance of new coupling devices for river-sea transportation; widely usage of CFD modelling; interaction effects for two equal hulls with high block coefficient (until now connection-effect coefficients CZ are used that were proposed by V.V. Zvonkov in 60s basing on trials of TBC of inner waterways).
3. Investigations in the field of coupling devices for TBC and IV were carried out by V.P. Lobastov, S.V. Presnov and other colleges. Analyze of existence coupling devises showed that they must be accepted for each concrete line and wishes of the customer, taking into consideration the structural restrictions of these gauges themselves.
Semi-rigid coupling devices are recommended for RSV that effect long marine voyages, because existing flexible and river semi-rigid coupling devices don't correspond to voyage conditions (despite successful experimental voyages of TBC that included barges and "OT-2000" pusher tugs in Azov Sea, also successful operation of TBC included NBL-90 barges and POSS-115 pusher tugs in Dnepr-Bug estuary). Rigid marine coupling devices have exceed characteristics for pointed sailing region; that increases significantly cost of coupling device itself.
Semi-rigid coupling device "Articouple" is recommended for usage at line Dnepr River - Black Sea - Danube River or line Dnepr River - marine ports of Black Sea or Azov Sea. Such device is able to save useful barge's length and provide satisfactory seakeeping and strength qualities of TBC.
Semi-rigid river coupling device of "O" type is recommended for usage at line Dnepr River - Ochakov (Trutaev bank); this device required 2 m wave restriction when passing Dnepr-Bug Estuary. At more strong waves at marine part till the Ochakov, the towage by the tow wire should be used; all this significantly decreasing construction's cost.
4. Principal differences TBC and IV from self-propelled vessels were demonstrated in the work. The main advantage of these vessels is realization of more effective schemes of cargo delivery to the destination. If shipping company has corresponding guaranties for constant cargo flow or is a cargo owner too, then realization of discussed advantages is clear while all links of logistic chain are organized properly.
5. Investigation concerning operational risk of RV and RSV including TBC and IV was carried out; vessels' age influence on shipping safety is argued. The steady growth of breakdown for vessels older than 13 years with peak of accidents for 22-25 and 30-34 years old ones are observed. One may pay attention at the huge number of TBC catastrophes comparing with general statistics (46% against 30%), especially with hull damage. It's explained by the fact that more "cheap" cargo section (barge) is often left without adequate supervision from shipowner, coast organizations and oversight bodies.
It may be pointed that there were catastrophes when TBC have flooded in coupled condition. The main reasons were: barge's underloading, breaches of region or conditions of shipping and TBC overkeel as a result.
So, the following hazards are the mostly dangerous for investigated vessels: compartments' watertight breaches as a result of cargo operations, navigations mistakes (contacts with sluice walls, grounding, etc.) or corrosive wearing; breaching of loading/unloading order or weather forecast mistake, that require existence of additional strength reserve for hull. Moreover, recommendations for design of some hull elements are given in the work.
6. Main particulars of RSV are fully defined by way restrictions, in other words "Max" conception is actually optimal for mass cargo transportation. On the basis of way conditions analysis it is possible to recommend overall length of 140-150 m for river-sea self-propelled pusher vessel of "Dnepr Max" type (length of the cargo section of the TBC should not exceed 120 m). Overall length of the TBC should not exceed 270 m. The overall breadth of the vessel could be accepted in the range 16.0-17.2 m (depending on the availability of additional thrusters). Vessel's air draught should not exceed 16.7 m (for the operation through Dnepr River downstream Zaporozhe). For operation upstream Zaporozhe till Kremenchug maximal air draught is 14.5 m; for operation upstream Kremenchug maximal air draught is 12.8 m. For operation upstream Zaporozhe maximal air draught is 8.57 m without waiting of Kremenchug bridge drawing and Dnepropetrovsk double-deck bridge drawing.
Main restrictions for TBC and IV operation at Ukraine internal waterways are taken into consideration, including definition running width occupied by TBC at river's turn. This running width at river's turn doesn't exceed fairway's width for TBC of "Dnepr Max" type that are foreseen to operate by scheme 1+1 (pusher vessel plus barge) with overall length 260 m and overall breadth 17.2 m.
7. Analysis of the way conditions for further accepting of main particulars of TBC and IV (example for "Dnepr Max" class).
Conditions that influence at accepting the overall length LM
Parameter Maximal available value LM, m
Minimal radius of Dnepr River fairway
Rmin = 800 m
LM ≈ 282 (for TBC breadth 17.2 m)
Port berths' length LB = 120...350 m 120 (for cargo section of TBC),
140-150 for self-propelled vessel
Minimal length of the working lock of a sluice LS = 150 m 150 (for operation upstream of Kiev sluice),
270 (for operation downstream of Kiev sluice)

Conditions that influence at accepting the overall breadth, BM
Parameter Maximal available value BM, m
Minimal breadth of the working lock of a sluice (for Dnepr River) BS = 18.0 m 17.2 (without accounting of ice cover; breadth reserve not less than 0.4 m from ice edge is allowed when ice appears on sluice walls)

Conditions that influence at accepting the draught, d
Parameter Maximal available value d, m
Dnepr River, depth of fairway dFW = 3.2...3.85 m 3.00-3.65

Conditions that influence at accepting the air draught, HAD
For operation upstream of Zaporozhye without waiting drawing of Kremenchug bridge and Dnepropetrovsk double-deck bridge value of HAD = 8.57 m. For operation downstream of Zaporozh'e value of HAD = 16.70 m.
8. During work effecting model test in towing tank were carried out; as a result of these test connection-effect coefficient was defined for combination of self-propelled pusher vessel and barge of "Dnepr Max" type with Cb = 0.930. Formula for connection-effect coefficient CZ (for whole IV) depending on Froude number Fr is as follows: CZ = 0.259 + 32.64Fr - 493.25Fr2 + 2179.50Fr3. When Fr > 0,07 (for whole IV), the better interaction between hulls of pusher vessel and barge is observed.
9. Main variants of operation for TBC and IV of "Dnepr Max" type are fixed:
• the "rotator" scheme, that includes single pusher tug and several barges; this variant is intended for cargo transportation from port to port (model line for basic summer navigation is Svetlovodsk - Izmail);
• pusher tug and single barge; this variant is intended for cargo transportation from river ports to marine ports or ports of other river basin or to port's road transshipment complexes (scheme "self-propelled vessel", model line for basic summer navigation is Svetlovodsk - Izmail);
• self-propelled pusher vessel and single barge; this variant is intended for cargo transportation from river ports to port's road transshipment complexes (model line for basic summer navigation is Svetlovodsk - Trutaev bank).
Results of comparing of non-discount payback periods TO with accounting fuel cost changing are as follows:
Operational variant Fuel cost CF, $/t (%)
TBC of "Dnepr Max" type. "Rotator" scheme 7.69 7.79 7.90 8.01 8.12
TBC of "Dnepr Max" type. "Self-propelled vessel" scheme 8,.20 8.29 8.39 8.49 8.60
IV of "Dnepr Max" type.
(River port - port's road transshipment complex)
6.16 6.20 6.23 6.27 6.31
Note. Optimal conditions with minimal payback period are accepted for each variant. For all variants Cb = 0.93, operational speed VS = 9.5 kn.

10. Analysis of the discussed models shows that determining of the most effective block coefficient Cb for mixed transportation is a complex problem of finding the "golden mean".
Vessel with the maximal available block coefficient Cb for the set speed range is mostly effective for mixed cargo transportation at the field of today river and river-sea transportation of the mass cargo. For the speed range of 8.5-10.0 kn (the main range for existing RSV) block coefficient of 0.93 is mostly effective; the bigger value of bock coefficient induces sharp increase of towing resistance and consequently fuel expenses; the smaller value of bock coefficient leads to less capacity of the carried cargo and consequently to the worse economical rates while keeping the same port and different navigational expenses (passing through locks or under bridges) and also crew salary.
Thus, for "Dnepr Max" type vessels it's recommended to use block coefficient Cb = 0.93 for river draught 3.6 m at usual river operational speed 8.5-10.0 kn.
The concept of the "Dnepr Max" type INTEGRATED vessel looks as the most realized. "Rotator scheme" and TBC concept in a whole demands the guaranteed constant cargo flows with the developed logistic chain; but now that is problematic.
Existing IV that consists of self-propelled pusher vessel (prj. 19620) and barge (prj. 90035) has the summarized cargo capacity about 4000 t for river draught 3.2 m. Proposed "Dnepr Max" IV concept is available to carry about 9700 t of cargo at draught 3.2 m, i.e. 2.4 times bigger for each voyage.
11. Main particulars of the proposed IV are as follows:
Parameter "Dnepr Max" integrated vessel
pusher vessel barge IV in whole
Minimal vessel's class M-PR O-PR -
Length overall, m 141.00 121.50 262.50
Length between perpendiculars, m 138.91 120.20 -
Breadth overall, m 17.20 -
Breadth, m 17.00 -
Depth, m 6.00 5.00 -
Block coefficient (river draught T = 3.2 m) 0.930 -
Block coefficient (marine draught T = 4.2 m) 0.937 -
Marine / river summer freeboard draught, m 4.20 / 3.20
Deadweight, t:
- for river draught 3.20 m
4879 4876 9755
- for marine draught 4.20 m 7376 7038 14414
Speed (kn) at % of engine's full capacity about 10.0 (100%) (for IV);
about 10.5 (85%) (for pusher vessel alone)
Cargo holds' capacity, m3 8715 9170 17885
Number of cargo holds 4 6 10
Main engines capacity, kW 2 x 1200 - -
Crew/ places, people 10 / 12 - -

1. Mathematical model of engineer and navigation properties of TBC and IV was significantly improved basing on methods of correction-regression analysis usage and special developed author's experiment. This model is intended for application in river and marine transport systems; it connects her properties with desired optimal main particulars of the investigated objects. Connection-effect coefficient was defined for combination of self-propelled pusher vessel and barge of "Dnepr Max" type with block coefficient Cb = 0.930 for the first time; results were got with help of model test in towing tank. Formulae for clause-by-clause weights calculation for self-propelled and non-self-propelled RSV with block coefficient Cb > 0.90 were defined also for the first time. Regression dependences for design of self-propelled RSV new generation are improved; they include ones for vessel's hull, engines' capacity, specific cargo capacity of dry-cargo vessel. Methodic for towing resistance and power definition for TBC and IV was improved by the results of model tests and operational experience of self-propelled RSV with Cb = 0.930.
2. Mathematical model of TBC and IV operation that was created for the first time; model ensures defining of efficiency indexes for TBC and IV operation and forms trivial and functional restrictions of the optimization problem. This model is developed as a result of analyses of water routes' structure and weather conditions of these routes and also with help of modelling methods of determined water-transport operations. Formulae for duration of round voyages for different operational schemes of TBC and IV are developed. Formulae for defining of speed loss at marine voyage for RSV with big Cb are developed. In the result of data processing concerning wind-wave condition of the Northern-Western part of the Black Sea, frequency of occurrence for 3%-probability 1-3 m waves was defined for marine part of voyage route during summer and winter navigations. This frequency values were used for determination of speed realization coefficient for discussed IV. By the way of statistical data processing concerning expenses of shipping companies that operate RSV, improved formulae for operational expenses' components were defined.