ADVANTAGES AND DISADVANTAGES OF RO-RO SHIPS

Ta diplomska naloga zajema opis tako prednosti kot slabosti Ro-Ro ladij, in sicer s finančnega vidika, vidika varnosti, stabilnosti, opreme, ki jo potrebujejo, in veliko ostalega. Kot vsaka stvar imajo tudi Ro-Ro ladje določene slabe in dobre lastnosti. Različne organizacije se trudijo slabosti izboljšati, vendar vseh vseeno za zdaj še ne morejo. Ena izmed velikih prednosti je seveda nizka cena, saj ladja zaradi svoje velikosti sprejme veliko število vozil, ki jih lahko prepelje naenkrat. Velika prednost je torej vpliv na okolje, saj onesnažuje veliko manj, kot če bi enako število vozil prepeljali po cesti. Ne potrebuje zelo naprednih nakladalnih naprav, saj ima v ta namen rampo, po kateri se tovor sam pripelje na palubo. Zaradi tega potrebuje zelo kratko operativno obalo in ne potrebuje skladiščenja na njej, saj lahko tovor hitro zapusti pristanišče po cesti ali železnici. Poznamo veliko vrst Ro-Ro ladij in vsaka ima svoje posebnosti in svoj namen, zato da se izpolnijo različne potrebe po prevozu mešanega tovora. Lahko prevažamo samo avtomobile (angl. Pure Car Carrier – PCC), avtomobile in tovornjake (angl. Pure Car and Truck Carrier – PCTC), zraven tega tovora na kolesih še specialne tovore (kontejnerje, les itd.) ali pa zraven vozil še potnike. Glavni slabosti Ro-Ro ladje sta zagotovo njeno visoko nadvodje in tovor, ki je vkrcan visoko na zgornjih palubah, saj to zelo poslabša njeno stabilnost. Ladje so zelo občutljive na manjše premike tovora, ki ni dovolj dobro pričvrščen, občutljive pa so tudi na vremenske pojave, na primer veter in valove. Rampe in vrata pripomorejo k neprepustnosti, ampak v notranjosti ni prečnih fiksnih pregrad, ki bi zadržale vdor vode le na enem delu palube. Če pride do poškodbe trupa, voda vdre v ladjo in zajame celo palubo. Zaradi tega se ladja hitro začne nagibati in v tem primeru je več ni mogoče rešiti. Še ena izmed slabosti pa je prostorska nezasedenost, saj ostaja veliko neporabljenega prostora med vozili ter pod in nad njimi, ker jih ne moremo zlagati enega na drugega. Prostor prav tako zasedajo notranje rampe in dvigala. To omeji kapaciteto za polovico.This undergraduate thesis includes description of pros and cons of Ro-Ro ship from financial aspects, aspects of safety, stability and equipment. As every other thing these ships have many shortcomings as well as advantages. Many organisations are trying to fix the problems and issues but some of them are not that easy or able to change. One of the greatest pros is surely low cost of transport, because this kind of ship accept a vast number of vehicles at the same time. Big advantage is environmental effectbecause they pollute a lot less than if all the vehicles were transported via road. Ship does not need advanced loading equipment because she has a loading ramp that vehicles use to board the ship. Because of this, she needs very short operative coast and she does not need stowage place on the shore, because vehicles can leave using the road or railroad. There are many different types of Ro-Ro ships and each has different special features and special purpose, for fulfilling requirements. We can transport only cars (PCC), cars and trucks (PCTC) and also special freight (containers, lumber…) or even passengers besides wheeled cargo. Main weakness of Ro-Ro ship is her high freeboard and cargo, loaded on higher decks, because it compromises her stability. She is sensitive even for the small movements of cargo that is not secured enough. Weather like rough sea and wild wind can also endanger her stability. Ramps and doors help maintaining water impermeability, but inside the ship, there are no transverse fixed bulkheads to retain the water intake on one place. If there is a breach in the hull, water can get in the ship and covers the whole deck. After that, ship rapidly starts to list and she is already doomed to capsize. Another weakness is spatial incompleteness, because there is a lot of unused space between, under and above the vehicles, since we cannot stack the cargo. Some space is also taken by inner ramps and lifts, which halves cargo capacity

UNDERWATER NOISE IMPACT ON MARINE LIFE

Onesnaževanje s hrupom se je šele pred kratkim začelo smatrati kot resnična težava, saj so zakonodaje o njegovem zmanjševanju v veljavo prišle komaj nekaj deset let nazaj. Kljub temu pa hrup predstavlja veliko grožnjo predvsem pod vodo, kjer se večina morskih organizmov zanaša na sluh. Zvok se pod vodo širi kot mehansko valovanje, ki se prenaša skozi vodni medij in ker se v vodi bolje ohranja kot v zraku, ima večjo sposobnost potovanja na večjih razdaljah brez izrazitega slabljenja. Splošno rečemo, da je hitrost zvoka v morski vodi približno 1500 m/s, vendar je hitrost odvisna od temperature, slanosti in tlaka v vodi. Z večjo globino je povezano nižanje temperature ter višanje slanosti in tlaka, hitrost zvoka pa je s tem tesno povezana, saj se zvišuje ob višanju teh lastnosti in pada ob nižanju. Vendar pa temperatura pada le do neke točke, ko ostane konstantna, in na tej točki ima hitrost zvoka najnižjo vrednost. Temu rečemo SOFAR kanal, po katerem se zaradi refrakcije zvok lahko širi skoraj na drugo stran sveta. Hrup negativno vpliva tako na morske sesalce kot tudi na deseteronožce, mehkužce, ribe, glavonožce, iglokožce in ostalo, saj ima vsaka od teh vrst sluh razvit za komunikacijo s svojo vrsto in zaznavanje plenilcev, ne pa tudi za kontinuiran zvok, ki ga povzroča ladijski promet, in impulzni zvok, ki ga povzročajo ljudje z eksplozijami, zabijanjem pilotov in ostalimi podvodnimi deli. Takšen hrup lahko pusti dolgotrajne posledice, kot je izguba sluha pri sesalcih, začasna izguba služnih dlačic pri ribah in podobno. V Sloveniji so se meritve podvodnega hrupa začele leta 2015 s strani Inštituta za vode Republike Slovenije, ko se je Slovenija priključila projektu QuietMed, programu, ki se zavzema za izboljšanje stanja morskega okolja na področju hrupa v celotnem Sredozemskem morju. Iz delnih podatkov za leti 2019 in 2020 so bili izvzeti urni podatki, ki prikazujejo, koliko se je količina hrupa v slovenskem morju spremenila v enem letu. Hrup je bil merjen na več različnih frekvencah, v nalogi pa so bili analizirani le podatki za dve frekvenci, in sicer 63 Hz in 125 Hz, saj nizkofrekvenčni zvok potuje dlje, glavni vir hrupa na teh dveh frekvencah pa je ravno ladijski promet. Podatki so bili nato upodobljeni na grafu in potrjujejo, da je količina hrupa, kljub globalni epidemiji, ki je omejila ladijski promet, še vedno naraščala.Noise pollution has only recently started to be seen as a real problem, with legislation to reduce it only coming into force a few decades ago. However, noise is a major threat, especially underwater, where most marine organisms rely on hearing. Underwater, sound propagates as mechanical waves that are transmitted through the medium of water and, because it is better preserved in water than in air, it has a greater ability to travel over greater distances without significant attenuation. The speed of sound in seawater is generally said to be about 1500 m/s, but the speed depends on the temperature, salinity and pressure of the water. As depth increases, temperature decreases and salinity and pressure increase, and the speed of sound is closely related, increasing as these properties increase and decreasing as they decrease. However, the temperature only decreases up to a point where it remains constant, at which point the speed of sound has its lowest value. This is called the SOFAR channel, through which sound can propagate almost to the other side of the world due to refraction. Noise has a negative impact on marine mammals as well as on decapods, molluscs, fish, cephalopods, echinoderms and others, since each of these species has hearing developed to communicate with its own kind and to detect predators, but not for the continuous sound caused by shipping and the impulsive sound caused by humans with explosions, pile driving and other underwater work. Such noise can have long-lasting effects, including hearing loss in mammals, temporary loss of hearing hairs in fish, and so on. In Slovenia, underwater noise measurements started in 2015 by the Slovenian Water Institute, when Slovenia joined the QuietMed project, a program that aims to improve the marine noise environment throughout the Mediterranean Sea. The partial data for 2019 and 2020 exclude hourly data that show how much the amount of noise in the Slovenian sea has changed in one year. Noise was measured at several different frequencies, but only data for two frequencies, 63 Hz and 125 Hz, were analyzed in this thesis, as low-frequency sound travels further and the main source of noise at these two frequencies is shipping. The data was then plotted on a graph and averaged to calculate the noise levels for each frequency in 2019 and 2020. Comparing the averages confirms that, despite the global epidemic that has restricted shipping, the amount of noise is still increasing