DESIGN, EVALUATION AND VALIDATION OF SHALLOW DRAUGHT VESSELS

Charlie Than

Myanmar Maritime University

Thilawa, Thanlyin, Yangon, Myanmar

Fax: +95-56-22175

email: mmu02@mmu.gov.mm

Abstract

In order to initiate the implementation of Logistic Services along the Ayerwaddy River of Myanmar, the optimum shallow draft vessels were designed, evaluated and validated. Trains of two barges and four barges were considered for this study and their effectiveness and validation in shallow water canals were examined. As a first step, using resistance equation of Howe and Bronzini, theoretical approach was carried out. Secondly, design calculation was established with NavCad software. Thirdly, model test was carried out in towing tank which is constructed on ground to be similar with actual river condition. The results from the trains of barges were then compared with the results from single barge. The results of the model tests were checked theoretically by using the ITTC 57 method and ITTC 78 method. It is seen that using the selected combined train of tug and barges is more effective than the self-propelled barge in the shallow water condition of the Ayerwaddy River.

Keywords: Ayerwaddy River, shallow draft vessels, Logistic Services, resistance equation of Howe and Bronzini, NavCad, ITTC 57, ITTC 78

1. Introduction

Cooperation between waterway and road transportation is important for combined transportation so as to achieve the proper logistic service in Myanmar and it needs to promote to Combined Transport and Intermodal Transport, step by step. To perform these tasks, Myanmar has the Ayerwaddy and the Chindwin rivers which are the vitals for Myanmar. If they can be utilized effectively, there is a great potential for economic growth instead of using rail and road transportation alone. However, according to the geographic features of Myanmar, the whole parts of the Ayerwaddy flows throughout inside Myanmar and as a result, the experts from international could not reach for its development study efficiently yet. At the same time, we can see a lot of international cooperation trying to implement combined transport and intermodal transport for Mekong River which flows across the eastern part of Myanmar and Kalatan River at the western part of Myanmar. Due to the distinct geographic features of Ayerwaddy, instead of waiting the international involvements, it needs to initiate to develop the logistic service of Ayerwaddy by our own strength.

2. Inland Water Transport

Inland navigation is very competitive in relation to other land transport modes. Pushed tow of barges can generate more ton – kilometers per distance unit than any other mode of the surface transport modes. Only pipeline transportation is more cost – effective than inland navigation, but it also has certain disadvantages like volume of investment, capability of only one type of liquid cargo (mostly crude oil and gas), need for the flow to be always constant and to correspond to the full nominal capacity and travel conditions that reduce its flexibility. All these results in transportation of the liquid cargo by inland waterways very often being more cost effective that by the pipeline.

Exactly established advantages, disadvantages and real relations between the surface transport modes and inland waterway transport is not possible to describe quantitatively in a simple way due to different and complex functioning conditions and environment where they are taking place. Only the general relations between the costs and operational indicators could be presented, which values are averaged according to significant statistical values (turnover volume, total costs, average power, etc).

According to the data from various international and national associations and scientific organizations in the world, the advantages of the inland waterway transportation are the following:

(1) Cost – effectiveness;

(2) Least consumption of the propulsion energy;

(3) Least quantity of material needed for the construction of the transportation means per ton of the transported cargo;

(4) Navigation safety;

(5) Environmentally most friendly type of cargo transportation and

(6) Least land use.

The main disadvantages of the inland waterway transportation are the following:

(1) Limited geographic expansion;

(2) Pronounced influence of current hydro – meteorological conditions;

(3) Quality level of the transport service.

The misconceptions about the inland waterway transportation include the following:

(1) Inland waterway transportation is slow;

(2)Type of cargo is of decisive influence for the choice of the inland waterway transportation as the main transportation carrier in the inland transportation chains;

(3) Inland waterway transportation is isolated and out­dated transportation system.

Today is the main goal of the transport policy and strategy, at continual and rapid growth of the cargo transportation, such mode of transport, which makes least environmental damage and uses the existing infrastructure as less as possible. In this sense, there is no doubt that the inland waterway cargo transportation in general is the least damaging mode and that its natural infrastructure can be most efficiently used.

3. Ayerwaddy River and Inland Water Transport ⁽¹⁾

Myanmar is well endowed with natural resources, such as oil, copper, coal and timber, which are mainly concentrated in the central and northern regions of the country. The delta of the Ayerwaddy in southern Myanmar is one of the great rice granaries of the world, and a wide variety of agricultural crops are grown in the Ayerwaddy, Chindwin, Sittaung and Thanlwin river basins which traverse the country in a North—South direction.

The Ayerwaddy and Chindwin Rivers are the principle arteries of riverine transport in Myanmar, providing a direct link between up-country trade and/or population centres, such as Mandalay, Monywa, Sagaing, Pakokku, Minhla, Kyangin, and the capital and export centre of Yangon.

River transport on the Ayerwaddy and Chindwin Rivers was already well developed in the nineteenth century and the development of the railways from 1914 onwards met effective river transport competition, whilst road transport in the Ayerwaddy and Chindwin has served as a distributory rather than a competing mode.

In view of the importance of inland waterway transport to the economy and development of the nation, this study has been designed to develop economically and technically feasible schemes for making short term, medium and long term improvements of the navigability of the Ayerwaddy and Lower Chindwin Rivers, using, to the degree practicable, local materials and low cost methods, and to strengthen the capacity of the Authorities to plan and execute these tasks.

At present, the water level of Ayerwaddy River in dry season is relatively low for the cargo draught of ship and the navigational routes are long, meandering and changing all the time in many places. So the available water way for navigation is needed to know for every instance which is mainly different from land transport. Moreover, although there have enough water levels in deep water season, it is also difficult to know the correct waterway for navigation because of flood in all areas of river including its surrounding. So, it is not easy for maneuvering and handling and it experiences potential rates of collision of bridges piers against vessels due to the fast flow rate of the river.

It is evidenced that the effective and correct technology is needed for economical transportation in Ayerwaddy River throughout the whole year. The first way of this required technology includes conservation of the navigational route and installation the marking buoy for navigational route. The other way is to design and construct the vessels which are suitable for the present water way. The latter is to use the latest electronic navigational system and or ECDIS and RIS that investigate the fair way to operate which should record every time, and as a result, fuel consumption can be reduced efficiently. At the time the methods mentioned above could be implemented dramatically, it can be analyzed that Ayerwaddy River can be highway for combined transport, intermodal transport and multimodal transport in Myanmar.

Nowadays, the transportation cost raises more and more with the high fuel price, and the requirement for transportation is to be available the vessel which can be operated at low cost. For this demand, this research has been carried out to design and build the cargo carrying vessels for the intention of intermodal transport in Ayerwaddy River.

4. Design Consideration for the Vessels

From the observation, the topography of waterway has restricted the overall length of ship approximately LOA = 100 m between Yangon to Mandalay and breadth of about 80 feet can be used which meets the restriction of canals, span of bridges piers along the river. In the case of draught, H = 1.5 m for draft can be used between Yangon Mandalay waterway and keel clearance should be 30% of water draught in river. Furthermore, the vessels should be chosen which can carry many loads within 30% keel clearance.

Based on these requirements, the type of vessel which may be self propelled barge or tug and barges system in which many barges are pushed by a tug. According to consideration and topography of river, self propelled barge can be difficult to pull itself at the incident of grounding. And if the ship is very long, there would be the possibility of ship hogging from its midship while it become grounding. It is also difficult to handle in bent parts of river requiring long carriage for docking procedures. By analyzing the vessels used in international for effective usage of intermodal transport and multimodal transport, it can be proved that tug and barges system is most reliable for that kind of transportation in Myanmar. Hence, in this research, the combined train of tug and barges system was chosen for implementation of intermodal transport.

As we chose the combined train of tug and barges system for this research work, their dimensions also have to be considered. According to historical data of the department of Inland Water Transport, the largest vessels having overall length of 110 m could be operated well in Ayerwaddy river. After gaining independence from British in 1948, tug and barges system which means the combined train of four barges pushed by single tug for oil carrying purpose was used for the waterway between Mandalay and Chauk. In term of those barges, the overall length of one barge is 160 feet, breadth is 29 feet. The overall length and breadth becomes 320 feet and 58 feet, respectively, for the operation of combined train of four barges. Moreover, as the overall length of tug is 103 feet, the total overall length of combined train of tug and barges system is about 423 feet. But, in the case of combined train, distinct advantages is what tug can push two barges after two barges in bending parts and very restricted waterway. Another way used in ancient time is so called abreast tow. It means that one or two barge are connected to the side of main vessel and the whole train of main vessels and connected barges are operated altogether in order to extend second dimension (breadth) for there have not enough water depth in river. The overall length of main vessel was about 100 m and breadth was about 50 feet including paddle. And the connected barges have breadth of about 34 feet. This is the way of water transportation used in last century.

Therefore, it can be seen that the maximum overall length of vessel in Yangon to Mandalay waterway are about 110m and that in Mandalay to Bhamaw waterway are about 55 m. Based on this figure, the overall length of 160 feet (48.769 m) and breadth of 29 feet (8.83m) were adopted as the dimensions of one barge for this research of combined train of tug and barges system.

5. Methodology, Results and Discussion

5.1 Methodology

In this research, the resistance value was determined by using three steps. First, theoretical approach was carried out by using the resistance equation of Howe⁽²⁾ and Bronzini⁽³⁾ in accordance with the actual water level of Ayerwaddy river. Second, the calculation was established by using Navcad software with the input data of barges, the available depth of water in river, channel width and Ayerwaddy river conditions. Third, the model test was carried out in towing tank to measure the resistance value of one barge in deep water condition, four barges in deep and shallow water condition and combined train of tug and barges in deep and shallow water condition. The towing tank in this study is constructed on ground to represent the actual river condition(see Fig.1&2).

Also, the calculation for the model tests were carried out by ITTC57 & ITTC78⁽⁴⁾ methods and the form factor was formulated by using the Watanabe and Alexander formula Equation⁽⁵⁾. This research produced the Modified Equations for Ayerwaddy River going Barges as Follow:

Modified Form Factor

For Deep Water

For Shallow Water

Modified Alexander Formula for Ayerwaddy River

5.2 Results and Discussion

Based on the results of model study, theoretical calculation and NavCad software calculation, the comparative statements are as in the Table 1.

Table 1 Comparative study of experimental result and calculate result for combined train of four barges in deep water

No.	Speed (knot)	Model results (ITTC 1978) (EHP)	Calculated results (Howe and Bronzini equation) (EHP)	Calculated results (NavCad software) (EHP)
1.	3	77	32	25
2.	4	102	76	57
3.	5	138	148	109
4.	6	260	255	186
5.	7	308	404	291
6.	8	415	603	429
7.	9	616	859	606

Therefore, it can be concluded that the values of EHP by experimental methods and Howe's equation are nearly equal at 5 knots and 6 knots and that of experimental method and NavCad software are nearly equal at 7 knots, 8 knots and 9 knots.

And the EHP values of four barges at shallow water are shown in Table 2.

Table 2 Comparative study of experimental result and calculate result for combined train of four barges in shallow water

No.	Speed (knot)	Model results (ITTC 1978) (EHP)	Calculated results (Howe and Bronzini equation) (EHP)	Calculated results (NavCad software) (EHP)
1.	3	128	40	45
2.	4	234	96	57
3.	5	260	188	181
4.	6	305	324	307
5.	7	436	515	483
6.	8	709	768	726
7.	9	1523	1093	1055

	Fig.3 Comparative graph for speed Vs. EHP.

It can be analyzed that the values of EHP by Howe's equation and NavCad software are nearly equal at 3 knots, 5 knots and 7 knots. Besides, those of experimental method and NavCad software are nearly equal at 8 knots. As a most distinct feature, EHP values change abruptly after the speed exceeds 8 knots (see in Fig. 3).

6. Conclusion

As a conclusion to this research, selected combined train of tug and barges system can be proved as the maximum carrying capacity of about 2344 ton and least cost transportation system with the main engine capacity of about 1000 HP for the implementation of combined transport and intermodal transport in Ayerwaddy river. It can be seen that the optimum speed will be 6 knots for upstream of the Ayerwaddy river according to the experimental results and calculation results. In this speed, the requirements of the values of EHP are reliable and suitable. If we use main engine having 1000 HP, we can operate up to the speed of 9 knots in still water.

Hence, the combined train of tug barges system will be one of the effective ways for the implementation of the logistic service in Ayerwaddy River.

References

(1) Haskoning,Royal Dutch Consulting Engineers and Architects,” The Irrawaddy and

Chindwin Rivers Study”.

(2) Howe, C.W., Inland Waterway Transportation, Johns Hopkins Press, |Baltimore, Md., 1969, pp. 23-27.

(3) Bronzini, M.S., Lopez, L.A., and Stammer, R.E., "Inland Waterway Port Model: Design, Development, and Methodology," Transportation Center, University of Tennessee, Final Report Contract MA 79-SAC-00183, Jan. 1981, pp. 409-409.

(4) Volker Bertram, “Practical Ship Hydrodynamics”, 2000.

(5) Principles of Naval Architecture, .1.P. Comstock, Ed., SNAME, revised edition, 1977.