A PROPOSAL FOR THE MODELS AND MEASURES OF SEARCH AND RESCUE ON INLAND WATERWAYS

. Search and rescue on inland waterways are considered to be insufficiently developed. The methods of search and rescue have been developed only for sea waterways. Despite the possibilities of comparison, the specific characteristics of inland waterways are the reason why it is seriously considered to develop proposals for search and rescue models on inland waterways. The authors of this paper suggest a search and rescue model for rivers, lakes and channels regarding configuration and the current safety conditions on inland waterways. The model allows a successful quest for reduced search time. In addition, the model predicts the performance of the search


Introduction
Inland waterways are understood as navigationally passable waterways of rivers, lakes and channels organized, marked and open to safe navigation (Dadić et al. 1996;Rohács and Simongáti 2007;Ivakovic et al. 2008;Brnjac and Cavar 2009;Camp et al. 2010).Search and rescue services on inland waterways are considered as poorly developed.According to Jolić (2005) and and Vojković (2007), one of the reasons lies in the long predominance of sea tra c over tra c on inland waterways.Science and profession describe in detail search and rescue methods at sea where search and rescue operations are regulated by the International Maritime Organization -IMO (Zec 2001) that is obligatory and implemented in practice.
Inland waterways are being increasingly exploited.e reason lies in the economic cost-e ciency of trafc on inland waterways compared to other types of land transport (Communication from the Commission … 2006;Brnjac and Cavar 2009).However, safety on inland waterways is not developing at the same speed.us, for instance, on inland waterways, search methods have not been su ciently studied (Contesting it Sustainability … 2005).
Ships at sea are equipped with rescue means, including life jackets, lifebuoys, ra s, lifeboats, EPIRB (Emergency Positioning Indication Radio Beacon -EPIRB, COSPAS -SARSAT), SART (Search and Rescue Transponder -SART), pyrotechnic devices, etc.A part of this equipment is also used for search and rescue operations on inland waterways.Lifeboats and life-ra s are equipped with life-saving appliances.It is of great importance for ship crew members to get familiar with the means and equipment for rescue activities that can be found onboard their ships.
e Convention for the Safety of Life at Sea (SOLAS) regulates the obligation of ship crew members to be familiar with life-saving appliances and equipment which means independent handling, knowing equipment properties, a position of life-saving appliances onboard and means inventory (Zec 2001).
Ship crew members acquire a working knowledge of the basics of search and rescue operations through special courses stipulated by the International Convention on Standards of Training Certi cation and Watchkeeping -STCW 1978/1995.STCW Convention de nes search and rescue training.
e concept of the search de nes locating the position of people in distress which means that life or cra is in imminent danger.It may result in loss of human lives, injury to people, loss or damage of a ship, cargo and objects around the ship.According to SAR Seamanship Reference Manual (2000), rescue is considered successful if human lives are saved.
Rescue is considered even more successful if a ship is saved along with cargo.In general, rescue is consid-ered to be more successful if search time has been reduced to a minimum.Finding people and goods within the shortest time increases the possibility of survival with ship and goods not permanently lost.

Search on Inland Waterways
e search on inland waterways should be adapted to the con guration of inland waterways and temporary safety conditions on the waterway.Safety conditions on the inland waterway include: -waterway con nement; -in uence of water currents; -water level; -weather conditions; -other factors.e con nement of the waterway results from the size of that.e dimensions of the waterway are de ned by the width, depth and height of the passage on the inland waterway (Čolić et al. 2005).e waterline depends on the indentation and curves of the waterway.e curvature and indentation of the waterway directly a ect the visibility of the waterway.
Water currents on inland waterways are considered as signi cant factors that make rescuing more di cult, particularly in the period of extreme precipitations.During the search, the direction and force of water currents need to be taken into consideration.e force of the current depends on water ow supply.e current direction is determined by water ow unless the river or lakes have burst its banks.
Water level is the measure of water height for a certain area.Water level is proportional to water currents (Pomorski leksikon 1990).
Weather conditions a ect the method and results of search and rescue operations.Unfavourable weather conditions include: -reduced visibility; -precipitations; -occurrence of ice; -reduced air and water temperatures.Low temperatures may result from the in uence of air or water.e feeling of coldness increases with increased wind (Table 1), see National Search and Rescue Manual (2006).Inland waterways are considered colder than those at sea.During winters, ice o en occurs on many inland waterways.e threat for endangered people lies in the immediate contact with water.e danger of drowning due to the weather phenomena is high and may signi cantly a ect search and rescue duration.
Other factors are rare, have less in uence on the search results and therefore are not mentioned in this paper.
e exposure of the human organism to low temperatures causes hypothermia which is the fall of body temperature due to exposure to low temperatures.If the human organism is exposed to low temperatures for a longer period of time, death may be the result (Fig. 1, Table 2) (National Search and Rescue Manual 2006).e recommendation is searching by ship on river upstream.is procedure shortens time necessary to arrive to the search target since it moves towards searching means carried by the water current.e suggestion is to categorize waterways according to their search width.Considering such categorization, waterways may be: -narrow for searching; -wide for searching.e search for narrow waterways includes all waterways with both le and right bank lines clearly visible from the midstream under the current meteorological conditions.
e search for wide waterways is considered to be all waterways with both le and right bank lines not clearly visible from the midstream under the current meteorological conditions.
e current meteorological conditions are the current visibility, waves, wind, precipitations and other factors.is leads to the conclusion that the width of the waterway is a changeable variable for search and rescue and these operations will have to be adjusted to it.
Searching for narrow waterways should be parallel to the bank line, particularly in cases it is a narrower waterway and the search is performed by a single ship.It is suggested to start the search at a reference point which should be the point of the probable position of the searched object.e reference point for rivers can be calculated according to the relation: where: D -distance in km from the last known place of distress (the distance is calculated in the downstream direction, i. e. the direction in which the water ows); B r(max) -the maximum speed of the river current; t -a period of time from distress.
If the search is performed by several ships on a wide river waterway, it is recommended upstream and parallel with the bank line (Fig. 2).A wide waterway for searching is considered the waterway with bank lines that are not clearly visible from the midstream under the current meteorological conditions during search and rescue operations.e reference point should be calculated according to formula (1).e search should be carried out by forming several search sweeps the width of which should depend on the visibility and size of the searched object.e number of sweeps N s equals the number of course changes that is proportional to the searched waterway area and search route width: where: P pl -the searched waterway area; P st -search route area.e search conducted by a single ship on a wide river waterway should be upstream in zigzag courses (Fig. 3).For this type of searching, a ship of favourable manoeuvring characteristics and appropriate dimensions for waterway width is required.
e search in zigzag courses is suitable since there is less possibility of carrying the object downstream during the search on one side of the waterway.e number of course changes n k on a certain area in zigzag search from relation is calculated according to relation (2).
Since the waterway is de ned by the radius of curvature (Fig. 4), one may say that the waterway area of segment P pl is approximately equal to di erence in the areas of two circular sectors of concentric circles: where: l -the length of the bank line of the larger circular sector of the river curve; r -the curvature radius of the smaller circular sector of the river curve or where: E -the angle of the circle sector within the river curve; r -the radius of the curvature of the river curve.e above mentioned formula yields to the acceptable results of the river curves.For the straight river section (Fig. 5), the number of sweeps N s , is calculated as: e inland waterway can be presented functionally (Fig. 6).
If f 1 (x) is the le bank line and f 2 (x) is the right bank line, then the area between them equals the di erence of areas on segment (x 1 , x 2 ), i. e.: If inserted into formula (2): e number of routes is the estimate of on scene commander (OSC) that is suggested to be the master of the public service vessel in charge of search and rescue operations.Such a vessel may belong to the river coastguard, police, army, Harbour Master's O ce, etc. (Zec 2001).e number of sweeps should depend on the area of waterway segment P pl , search range (depends on visibility V isb and waterway curvature radius R), the size of the searched object M, the height of observer h and other factors ost.Generally, it should be expressed as follows: , , , , , , , , , e duration of search t t is calculated according to the formula: where: N os -the number of sweeps determined by the on scene commander; v b -the speed of a search and rescue ship.Formula ( 20) is valid only for the search using a single ship.If the search is performed involving several ships n b , then the following formula is valid: Search time depends directly on the success of the search: Search success is the probability of the positive search result the probability of which is de ned as a function of the probability of nding the searched object.It may have the value of interval (0, 1) and may be designated as K (Frost 1999): where: POC -the probability that the searched object is contained in the search area (Probability of Containment -POC); A -the search zone area.
If inserted into relation ( 21): On lakes, sea searching methods should be applied since there are no extreme water currents.
ese are methods for Expanded Square Search and Sector Search such as implemented in the sea search (Fig. 7) (Bowditch 2010).e length of navigation on a certain course, S, depends on the size of the searched object M, the height of observer h, visibility V isb , surface condition s tp (waves) and other factors ost.
, , , , In exploring the search area on lake inland waterways, it is possible to de ne the Search Area.e Possible Search Area is described as the minimum area in which it is certain that there are people in distress.is area usually has large dimensions, and therefore it is considered necessary to be divided into smaller areas (Frost 1999) (Fig. 8).Each smaller area is assigned the value of the probability of nding the search target POC.According to Frost (1999), POC can be determined for the simplest case according to the expression: where: R -total navigation error.
It is considered that a single or several points can have the same Probability of Containment.e most probable position of the search target can be determined as: -geographical point; -line; -area.e geographical point is designated as the highest Probability of Containment based on the collected data.All other points in the neighbourhood have a relatively lower Probability of Containment.e line or several lines are composed of the points of approximately the same Probability of Containment.An area is determined when it is impossible to determine a point or line as a part of the plane with the points of approximately the same probability (Zec 2001).
If the lake is described functionally (Fig. 9), one may say that the northern lake bank is function f 2 and the southern onef 1 .e area of the lake will be a crosssection of these two functions: f 1 and f 2 functions intersect at points x 1 and x 2 .e area of the lake described by the functions between the intersection points will be: e number of sweeps in ship search will be: e sweep is described by its length s and width a and has a form of an elongated rectangle.e area of route P s is: Width between sweeps a depends on the current conditions on water (Table 4).e length of sweep S is the sum of sweeps s which forms the mathematical series: It follows that the partial sums of the given mathematical series are as follows: of , it follows that: , the mathematical series diverges.
Since this refers to a nite order, i. e. k → N, then If inserted into formula (28), Search and rescue operations on lakes can be difcult due to meteorological hydrological conditions on water (Table 3 and 5).For example, such di culties may include strong wind, waves and strong currents.In cases of strong wind and currents, there may be certain dri (Kotsch 1984).e dri of the search target depends on the displacement of the search target, the size of the freeboard of the search target, etc. (Ljubetić 1989).e intensity of dri is presented in Table 4. Program packages should be developed to provide the on scene commander with the calculation of search time, the number of sweeps, search probability, etc. is would help the on scene commander in making decisions on the method of search coordination and in reducing the possible human errors and oversights.e program packages for computers should be developed according to a general algorithm presented in Fig. 10.

Conclusions
e theory of the search on inland waterways is considered to be insu ciently developed in comparison to the theory of the search at sea.A partial reason of underdevelopment can be accepted to be the insu cient usage of inland waterways compared to those of the sea.
Tra c on inland waterways has increased in the recent years since this branch of land tra c has been recognized as the least expensive one for transport.Infrastructure, suprastructure, tra c management organizations, inspection services and search and rescue organizations are thought to have failed to follow tra c development on waterways.
e International Maritime Organization should urgently elaborate the implementation of an adequate theory of search and rescue services on inland waterways and de ne the minimal equipment.At the moment, for instance in the Republic of Croatia, regulations on tra c, search and rescue, etc. rely on the Maritime Law.Such a solution is considered as insu cient due to the speci c characteristics of navigation on inland waterways.
Computer programs should be developed according to the proposals given in this paper in order to improve search and rescue services on inland waterways.It is justi ed to expect the programs to make it easier for river coastguard and on scene commanders to organize search and rescue operations.A better organization of search and rescue operations would contribute to greater success in the protection of human lives and assets and would greatly increase the safety of navigation on inland waterways.

Fig. 1 .
Fig. 1. e graph of the rate of body temperature fall for a lightly dressed person who does not move through water and wears a life jacket (National Search and Rescue Manual 2006)

Fig. 2 .
Fig. 2. Search by a single ship on the river upstream pl -the length of the waterway searching area.
Fig. 4. Values to calculate the number of sweeps

Fig. 8 .Fig. 9 .
Fig. 7. e search using the methods of Expanded Square Search and Sector Search

Fig. 10 .
Fig. 10.General search algorithm for the rescue of a drowning person on inland waterways

Table 1 .
In uence of wind on the perceived temperature(National Search and Rescue Manual 2006)

Table 2 .
Approximate time of death before fainting i. e. the death of a person of the average constitution(National  Search and Rescue Manual 2006)