136365.1 Particularities of Navigation on Inland Waterways

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    Particularities of navigation on inland waterwaysby Branislav ZIGIC, VBD

    IntroductionInland navigation is different from other modes of transportation because of the naturalcharacteristics of its main infrastructure, the river network. The dynamic nature of rivers (in terms ofchanging draught, varying waterway widths, etcetera) requires constant monitoring and operationalflexibility from operators in the inland waterway sector. The recent historic low water period on thehine and !anube clearly showed the interdependency between inland navigation and itsinfrastructure" due to the limited draughts, the economic performance of inland navigation isdirectly affected. #t other more strategic occasions the relation between vessel and waterway isalso of critical importance$ for instance in new waterway pro%ects, questions whether the waterwayshould be adapted to the available vessels or the other way around are sometimes evendominating the discussion.

    The &'I consortium presents in a series of two &'Iletter issues the backgrounds of the basicdependency between waterway and inland vessel. The first part deals with the physicalparticularities of inland navigation and is written by the uropean !evelopment *entre for Inlandand *oastal avigation +! from !uisburg. The second part - which will be published by viadonau in the next &'Iletter - discusses the economic implications of these physicalparticularities.

    Particularities of navigation on inland waterwaysIn comparison with the navigation in spacious and deep sea stretches the ship running on inlandwaterways meets certain specific restrictions. These restrictions characterised by shallow water ora narrow waterway or simultaneously and in most usual case - both have a large impact ontechnical performances and consequently on economic effects of inland vessels. /ence the mostdirect, at the same time the cheapest and most probably the only feasible way to optimise theeconomy of inland navigation leads over the thorough and comprehensive investigations of shipwaterway interactions. The knowledge gained from such investigations is needed for instance forthe determination of"

    0uidelines for the construction of navigable canals considering e.g. si1e, geometry,

    materials of bottom and side walls, effects of waves generated by moving vessels, %etstreams and vortices caused by propulsion devices$

    autically permissible and practically feasible speeds of ships$

    'ower requirements and propulsion characteristics$

    2anoeuvring particulars in restricted fairways$

    ehaviour of ships and pushed trains during passing by and overtaking in straight

    stretches and canal bends$

    2inimum space requirements for passing through, passing by and overtaking other floating

    ob%ects in canal bends, etc. etc.

    The first part of the following article aims at the presentation of facts, processes and behaviour ofvessels operating on inland waterways. Taking into account that a concerned reader might not befully familiar with shallow water hydrodynamics, respective physical lows and mathematical toolsan attempt was made to explain all relevant issues by applying the simplest descriptive approach.This basic technical knowledge will facilitate an easier understanding of practical restrictions and

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    relations applied when considering the economic effects of inland navigation as transport modewhat is exactly the primary goal of this review. The second article to be published in this seriesdeals with the

    1. Tyes of vessels on !uroean waterways and t"eir si#e

    There are principally three different means of transportation on inland waterways" by selfpropelledship, by barges pushed by a selfpropelled vessel (pushboat or pushing cargo ship) and by bargestowed by river tugs. The last method is nowadays almost completely abandoned on uropeanwaterways and might not be considered as typical any more.Inland vessels are classified according to their si1e and purpose. The target group here are cargovessels and these can be further distinguished by the kind of commodity, most generally into drycargo ships and tankers. #s far as the main intention is to show processes and relations betweenship and waterway the kind of commodity on board has no relevance for this particular topic. 3hatis important is the si1e of a ship. 4or selfpropelled cargo ships it varies from a small 5678 m long9peniche: having a cargo capacity of only about 588 t at ;.< m draught to a large ==8 m long rivership with on average about =>88 t capacity at the same draught. In recent times even considerablylarger vessels have become usual on the hine river having a length of up to =5< m, a beam of up

    to =? m (with allowance and trends to be further increased@) and a capacity of about 5

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    4ig. ;" *ross section of the navigable canal (waterway) of a river

    4airway width and depth characterise the navigability of rivers. Thereby the actual water level hasa decisive influence on fairway depth and thus on navigability.In general, freeflowing rivers have considerable water level fluctuations with amplitudes betweenseasonal lowest and highest level of

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    4ig. 5" Typical stern arrangement of an inland cargo ship D=D

    #lso ducted propellers (in no11le) are pretty usual on inland cargo ships. !ucted propellers mayproduce about ;8E more thrust than standard free propellers of the same si1e, but the problem isthat the installation of no11le additionally reduces the maximal allowable propeller diameter at thesame draught and hence diminishes the gain in thrust. &pecial executions of propellers like acontrollable pitch propeller (*''), rudder propeller (', also known as 9&chottel:) or cycloidpropeller (+&', 9+oith&chneider:) have certain advantages over the conventional 4'' but due totheir considerably higher price, sensitivity and vulnerability of mechanisms their application is notcommon on river vessels (except on e.g. some river passenger ships).

    &teering a ship means having control over her direction of motion. The most usual and simpleststeering device is the rudder. The flow of water around the rudder blade in inclined positiongenerates transversal force tending to move the stern opposite to the rudder inclination (4ig. 7).

    esides the simple streamlined single blade rudder there are numerous appendages andalternatives which to a certain extent improve the steering performances. These are for instancesection endplates, fishtails, flaprudders, twin or triplerudder arrangements, flanking and bowrudders.

    4ig. 7" 'rinciple of the rudder blade action D=D

    The common characteristic of all rudders is that the generated steering force depends on thespeed of the ship. The higher the speed the effect of rudder becomes better. &ocalled activerudders enabling maximal steering forces at low speeds, being very useful for a manoeuvre inconfined spaces (harbours, locks), are in fact water pumps accelerating a water %et in the selecteddirection. These pumps are usually arranged at bows and called 9bow thrusters: (4ig.

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    4ig.

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    influences of one running ship to another. Gnfortunately, with certain minor exceptions suchgenerous nautical conditions cannot be found anywhere on the uropean waterways. Thementioned exceptions relate only to the about ;88 km long !anube stretch in front of the Iron0ate I lock and several large water reservoirs on the +olga and !nepr in ussia andGkraine, respectively. /owever, smaller vessels set up lower requirements, especiallyregarding the waterway width. ut considering the fact that they also may have a draught of;.< m the above assessed water depth of about =< m represents more or less general therequirement for a waterway to be classified as 9unrestricted in depth:.

    arrow but deep waterway can eventually be found in certain gorges but on ma%or uropean

    waterways such cases are very unusual. are examples are the !anube stretch betweenriver km >?7.8 and >A

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    4ig. ?" 'ower diagram for different water depths D=D

    The power requirements of one conventional river cargo ship to achieve correspondingspeeds are presented in a parametric form as the function of water depth. ach curverepresents one water depth. It is to be noted that after achieving certain speed at extremelyshallow water even considerable increase of power has no influence on the shipCs speed.

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    == =; =5 =7 =< =A =? =6 => ;8 ;= ;;

    ;88

    588

    788

    88

    =888

    ==88

    =;88

    ,< x ;, ;8 ;= ;;

    h F infinite

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    &hallow and simultaneously narrow waterways are humanbuilt canals. The maximal

    attainable shipCs speed depends on the speed of propagation of waves, on the shape of thecanal (trape1oidal, rectangular, archform) and the ratio between the cross sectional area ofcanal and the midship section. !ue to the considerable dynamic immersion and trim underthe influence of shallow water in a canal as well as in order to prevent an erosion of canalbanks by generated waves this theoretically maximal speed is reduced by about =8E inpractice. &ome characteristic examples of existing canals with typical ships and theirbehaviour at different speeds are presented below (Tab. =).

    *anal &hip#rearatio

    #cD#s

    J

    *riticalspeed

    +sc

    kmDhJ

    Immersion

    cmJ

    #ttainablespeed

    8.> +sc

    kmDhJ

    Immersionat

    attainablespeed

    cmJ

    xample *rosssectional

    form

    #rea

    #cmLJ

    3aterdepth

    mJ

    readth

    mJ

    !raught

    TmJ

    hine2ain!anube Trape1oidal =?; 7.8 >..6 5=

    ==.78 ;.68 .< ?? 6.< 5..A 5=

    ==.78 ;.68 .; ?? 6.5 5. >5 6.> 75lbe/avel *anal ecti fied arch 6< 5.< >.88 ;.88 7.? 6.8 A5 ?.; ;>

    Tab. =" *ritical speeds for some canal cross sections D=D

    4inally, in flowing rivers the ship is additionally affected by the stream flow rate. #t low and normalwater levels the stream flow rate of most navigable rivers in urope is between 5 and 7 kmDh. Ifassuming a standard running speed through the water of =5 kmDh then the average shipCs speed

    over ground would be >=8 kmDh upstream and =A=? kmDh downstream. In case of extremely highwater the stream flow rate on certain river sections can arise to =8 kmDh or even more. In suchcircumstances the ship would be able to move upstream %ust very slowly and that is an additionalreason in addition to the danger of flooding and wave erosion why the navigation might be bannedwhen the water level exceeds a certain marking.

    (. )anoeuvre# ship operating in confined waterways, in relatively dense traffic, with sharp and narrow bends,numerous locks and bridges must match extraordinary high standards with regard to manoeuvringrequirements such as coursekeeping ability, turning, stopping, flanking, running astern etc. Theseabilities are important due to the very specific conditions of the navigation on inland waterways. 4or

    instance, when running straight ahead alone on a canal the ship will sporadically and nonintentionally come closer to one or to the other bank. Then the symmetry of flow will be derangedand the unsymmetrical pressure distribution around the hull will push the ship towards the nearerbank. In order to prevent collision the skipper would incline the rudder to bring his vessel back tothe centreline of the canal. That means that during her 9straight: run the ship will indeed make a91ig1ag: path consisting of permanent slight corrections of course heading. This path is evidentlywider than the vesselCs breadth. In general, slender ships have a better coursekeepingcharacteristic than short and broad ones. #s a rough estimate it can be said that for a =88 m longship at least =8 m wider than the shipCs breadth in upstream navigation and even =;=5m wider when headingdownstream D5D. Thus, the minimal twoway waterway width can be determined as the sum of thepaths of the vessels heading upstream and downstream, a mutual safety distance between them

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    and safety distances between each path and the ad%acent river bank. #ssuming very tightstandards for safety distances the minimal width of a straight line twoway navigable waterway ofinternational importance would be at least about A7 m (4ig.6).

    4ig.6" 2inimal waterway width for two way navigation of a standard inland vessels D;D, D5D

    There is another, more practical aspect for the width requirements of the waterway. 4irst of all, it isdesirable that a two way traffic of vessels is allowed along the whole waterway. That means thatbesides the sum of breadths of two ships or convoys whose dimensions do not exceed the allowedvessel dimensions on the considered waterway stretch a certain allowance must be added for thedistance between two bypassing ships as well as between the ship and the edge of the waterway.specially, a safety distance between two bypassing ships is very important and it is not only amatter of precision of the manoeuvre when bypassing. !ue to pressure distribution influenced bythe ship motion and the suction of propellers the whole ship and especially her after part tends tomove transversally and also to shift towards the vessel coming from the opposite direction (4ig. >).

    4ig.>" ypassing of two ships heading in opposite directions on the waterway with a restricted width

    This shifting force increases with the speed of motion through the water, respectively, with the sumof velocities of both passingby ships. Thus the virtual breadths of vessels heading in oppositedirections considerably rise during the passingby manoeuvre. ven though the overtakingmanoeuvre in narrow canals also requires utmost precision in steering the hydrodynamicconditions are not as unfavourable as during the bypassing.

    Bne of the numerous very demanding conditions for inland vessel is the safe operation whenpassing through the sharp river bends. #s a consequence of the common acting of various forceslike resistance, centrifugal and steering forces induced by rudder blades, a torque appears thatturns the vessel relative to the direction of its motion for socalled drift angle. In case of very longvessels like large pushed trains (4ig. =8) the free width of the path through the curve might beconsiderably bigger than the total breadth of the vessel. Bbviously, if two long ships or pushedtrains have to pass by each other in the river bend the fairway width requirements will be especiallylarge. In a lot of cases such manoeuvre is even impossible, or, if theoretically possible then veryrisky and skippers rather chose to wait for the ship coming from opposite direction at the spot

    where passingby is less dangerous, e.g. on straight stretches. !ue to more favourablehydrodynamic conditions it is the rule that vessels running upstream usually give precedence tothose running downstream.

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    4igure =8" 'osition of a pushed convoy during navigation through the river bends D;D

    #dditional very important manoeuvres for inland ships are 9crashstop:, turning, flanking (movingsideward) and running astern. 4or example all ships operating on the river hine are requested tofulfil very tight and precisely defined requirements for stopping. These requirements set up themaximum distances after which the ship has to stop after previously running at a certain speed.&topping in case of running downstream means not to stop move through the water but relative tothe ground. #ccounting high stream flow rates at high water levels propellers must then bring theship in running astern with a speed equal to the actual river flow rate. The importance of this abilityin inland navigation is also evident from the fact that only river vessels are additionally and

    mandatory equipped with a stern anchor which might assist to a crash stop manoeuvre in case ofemergency, to avoid collision or other accident.

    *. +elevant and decisive tec"nical asects and relationsThe above facts indicate the hydrodynamic complexity of inland navigation and very tight relationsbetween the running ship and the restricted waterway. In some cases there are certain physicalbarriers which cannot be excelled. These barriers are expressed through relations among the si1eof the ship, cross section of the waterway, the speed of the ship and power requirements to enablethat speed under given conditions. It is quite clear that the optimisation of the shipCs operation ininland waterways - and that means that the target function is the economy of operation can be

    done only for a concrete case and with a number of assumptions.evertheless, the following two examples illustrate the influence of the vesselCs si1e on the specificenergy requirements as one of the main components of each economic analysis and the influenceof hydrodynamic improvements on design of one large inland ship.The table below shows principal particulars of some typical inland ships starting from relativelysmall 90. Moenigs: classsi1e up to the latest trends to develop maximal si1e single vessels for theriver hine. The given propulsion power enables the speed of =5 kmDh at a

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    &hipCstype

    HengthmJ

    eammJ

    !raughtmJ

    !eadweighttJ

    '!k3J

    '!Dd3k3DtJ

    90. Moenigs: A?.8 6.; ;.< >A; =?? 8.=679N. 3elker: 68.8 >.< ;.< =;>5 =A8 8.=;7

    902&: ==8.8 ==.7 ;.< =>< 8.=889Nowi: =5

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    # more detailed exploration of the economic impacts of different waterway regimes will begiven in the next issue of the &'Iletter.

    +eferences9

    =. P4ahrdynamik von innenschiffen - #llgemeine infQhrung und 4olgerungen aus&chiffahrtsversuchen9, +erein fQr innenschiffahrt und 3asserstraRen e.+., !uisburguhrort, =>>;

    ;. PG!T - valuation of the !anube 3aterway as the Mey uropean Transportesource:, *onsortium of 'artners, +ienna!uisburg#thens, =>>A>6

    5. P0uterachtehrliche &tellungnahme 1u autischen #spekten des !onauausbaus&traubing +ilshofen am eispiel des heins und seinen ebenwasserstraRen9, +!

    ericht r.=5A>, !uisburg, =>>