Tuesday, October 8, 2013

Intretinerea motoarelor marine

 

Spre deosebire de motoarele auto, motorul de ambarcatiune functioneaza la turatii ridicate si sub sarcina ca mai apoi sa stationeze poate cu mult mai mult decit e cazul.
Astazi, motoarele marine sunt cu mult mai bine facute decit predecesoarele, nemaiaparind probleme mecanice reale, atit timp cit ele sunt bine intretinute.
Intretinerea pompei de apa. Majoritatea motoarelor de ambarcatiune suntsele racite cu apa pompata din exterior. Aceasta apa este circulata de o pompa care contine un rotor de plastic sau din cauciuc si astfel se realizeaza circularea apei in motor.
Reziduurile si diversele impuritati ajung la rotorul pompei, il uzeaza sau chiar distrug.
De asemenea, daca motorul este in repaus o perioada mai mare de timp, de citeva luni, uneori cauciucul rotorului pompei se farimiteaza sau chiar rupe. Prevenirea se face simplu, prin inlocuirea rotorului pompei de apa, dupa citeva sezoane. Daca rotorul cade chiar in momentul fuctionarii, semnele care anunta necesitatea schimbari sunt cele care tin de supraincalzirea motorului si de cresterea temperaturii.
Uleiul Schimbarea uleiului - motoarele marine, in mod obisnuit, nu functioneaza mai mult de 60-80 ore pe an si din aceasta cauza se recomanda schimbarea corespunzatoare a uleiului.
In mod obisnuit, se recomanda ca la finalul fiecarui sezon sa se schimbe uleiul si filtrul, cel putin o dat ape an.
Daca uleiul vechi, plin de reziduuri, intra in motor cind acesta e stocat, se va transforma intr-un component reactiv, coroziv, cu calitati chimice acide, cu efect asupra componentelor motorului. Se recomanda curatirea generala de uleiul folosit inante de conservarea motorului.
Injectoarele - majoritatea motoarelor marine folosesc injectoare in procesul de alimentare cu combustibil si acestea odata cu timpul, si cu exploatarea, incepe sa se blocheze sa dea rateuri . Pentru a evita un asemeea comportament, se recomanda ca in ultimul plin de combustibil sa adagati o solutie aditiv care sa ajute la curatirea injectoarelor, inainte ca motorul sa fie conservat.
Bateria - tine citiva ani, in mod normal, daca e corespunzator intretinuta. Se recomanda sa aveti un intrerupator general dar sa si vrificati circuitele pentru a nu ramine in cuplare eventuali consumatori. Pentru perioade mai lungi de timp, cind barca sta pe uscat, se recomanda decuplarea bateriei.
Sistemul de ungere al outdrive ului sau motorul outboard, trebuie sa ramina corespunzator lubrifiate, ansamblul transmisiei verficindu-se prin actonarea cu mina pentru a se vedea daca toate componentele se misca usor si se verifica de asemenea si nivelul lubrifantului.
Rezervorul care contine lubrifiant trebuie sa nu aiba urma de apa sau de condens, inspectia trebuie facuta minim anual odata cu verificarea stari componentelor.
Modulul de Control Electronic (ECM) regularizeaza curgerea de aer si combustibil stabilizeaza amestecul in corespondenta cu sistemul de aprindere. O alta functie importanta a modulului ECM consta in stocarea datelor operationale ale motorului pe perioada de functionare a acestuia.Mecanicii certificati au dispozitive digitale de diagnoza cu care se pot conecta la modulul ECM rezolvind probleme si analizind starea de fapt a motorului.
Anozii - Sunt proiectati pentru a fi sacrificati, prin electroliza, ei sunt cuplati pe partea exterioara si imersa a carenei sau partii de motor imersata, sunt facuti de regula din zinc, se deteriorefel se evita participarea altor parti din corpul navei la procesul intens de coroziune.Costul de schimbare al anozilor nu este scump, oricum este mic decit pagubele pe care le poate produce.

Wartsila Me Operations Manual


Marine Propellers and Propulsion

Lumea si portavioanele



Dupa 1990 natiunile lumii, cele care erau intalnite traditional pe mare, nu au mai construit nave militare, nici corvete, nici submarine si cu atat mai putin portavioane sau nave de transport navele de asalt.
Asa s-a ajuns ca foste mari puteri ale lumii sa aiba in exploatare si comanda cate un portavion cum e cazul englezilor italienilor, francezilor, rusilor, tailandezilor(da!, au un portavion).
Statele cu economia in expansiune au investit in portavioane si submarine, altele si au construit marina militara moderna.
Chinezii folosesc tot ceea ce gandirea navala sovietica a avut de varf, ultima lor achizitie fiind portavionul Variag care statea pe tarmul ucrainean de doua decenii. L-au adus acasa dupa peripetii pe mare si acte de eroism si acum e functional.
Indienii construiesc un portavion si mai au unul, tehnologia, proiectul ideea si sistemele de armament sunt fireste rusesti. Indienii au inchiriat si un submarin nuclear rusesc, Nerpa, submarin cu poveste si scufundare pe care l-au ridicat la suprafata si l-au dat indienilor in leasing, pentru trainingul echiajelor de submarin.
Cine nu stie ca in efortul de inzestrare al marinei iraniene, pe langa atatea arme rusesti sunt si submarinele din clasa Kilo, trei dintre ele au hartuit americanii in Primul Razboi din Golf si nu au fost gasiti.
Brazilienii construiesc submarine nucleare sub asistenta franceza, sunt din clasa Scorpene si vecinii lor argentinieni au si ei in constructie un portavion.
Un submarin, o corveta, un portavion sau o nava de asalt nu se ridica peste noapte. Dupa proiect si executie este necesar ca nava sa fie inzestrata cu sisteme de armament si apoi ea intra in probe cativa ani pana cand va deveni operativa.
http://cpoalelungi.blogspot.ro/2013/09/lumea-si-portavioanele.html

Costa Concordia la suprafata!

Cam un an si opt luni de la accidentul Costei Concordia si iata ca nava a fost ridicata la suprafata, in urma unui proiect ingineresc de exceptie!
Cu ajutorul unor cabluri nava initial a fost ridicata la verticala, atasandu-i-se pe borduri niste chesoane plutitoare si fiind asezata pe o prelungire a rambleului fundului apei si mai apoi sprijinita de un sistem de sustinere si plutire!
E spectaculos de vazut, au fost 12 ore extrem de tensionate, intreaga operatiune este un act de excelenta inginereasca!
Mai sunt de recuperat corpurile a inca doua persoane, au murit 32 de persoane din cele 4252 de imbarcati, un act d eprotectie divina si de mare sansa, inclucisv dupa cum nava a esuat pe insula Giglio.
Operatiunea este estimata la 1 miliard de euro, este interesant ca au fost voci care spuneau ca nava ar putea fi reparata si repusa in functiune, in fotografie ii puteti vedea partea pe care s-a asezat nava cu intreaga sa greutate!
Animatia ridicarii la suprafata pe CNN http://edition.cnn.com/2013/08/22/world/europe/costa-concordia-salvage-interactive/index.html

SHIP CONSTRUCTION- H.J.Pursey


Monday, October 7, 2013

Present day shipbuilding


China is an emerging shipbuilder overtook South Korea during the 2008-2010 global financial crisis as they won new orders for medium and small-sized container ships.[16] China is now firmly the world's largest shipbuilder with 45% of the world's total orders, and its quality and technology have improved very much. Today, South Korea is the world's second largest shipbuilding country with a global market share of 29% in 2012. South Korea leads in the production of large vessels such as cruise liners, super tankers, LNG carriers, drill ships, and large container ships. In the 3rd quarter of 2011, South Korea won all 18 orders for LNG carriers, 3 out of 5 drill ships and 5 out of 7 large container ships.[17]
Japan had been the dominant ship building country from the 1960s through to the end of 1990s but gradually lost its competitive advantage to the emerging industry in South Korea which had the advantages of much cheaper wages, strong government backing and a cheaper currency. South Korean production overtook Japan's in 2003 and Japanese market share has since fallen sharply. The market share of European ship builders began to decline in the 1960s as they lost work to the Japanese in the same way as Japanese builders have lost work to South Koreans more recently; Europe's production is now a tenth of South Korea's and is primarily military, although cruise liners and some cargo ships are still built in Italy, Finland, France, Germany and Denmark. The output of the United States also underwent a similar change.[18][19]
South Korea's shipyards are highly efficient, with the world's largest shipyard in Ulsan operated by Hyundai Heavy Industries slipping a newly-built, $80 million vessel into the water every four working days.[18] South Korea's "big three" shipbuilders, Hyundai Heavy Industries, Samsung Heavy Industries, and Daewoo Shipbuilding & Marine Engineering, dominate global shipbuilding, with STX Shipbuilding, Hyundai Samho Heavy Industries, Hanjin Heavy Industries, and Sungdong Shipbuilding & Marine Engineering also ranking among the top ten shipbuilders in the world.[20] In 2007, STX Shipbuilding further strengthened South Korea's leading position in the industry by acquiring Aker Yards, the largest shipbuilding group in Europe. (The former Aker Yards was renamed STX Europe in 2008). In the first half of 2011, South Korean shipbuilders won new orders to build 25 LNG carriers, out of the total 29 orders placed worldwide during the period.[21]
World shipbuilding market share by countries (2012)[16]
Rank Country Combined GT  %
1  China 67,000,000 45%
2  South Korea 53,000,000 29%
3  Japan 28,000,000 18%
4  European Union 4,500,000 1%

Rest of the world 11,000,000 7%

Modern shipbuilding manufacturing techniques


Construction of prefabricated module blocks of HMS Dauntless at BAE's Portsmouth Shipyard.
Modern shipbuilding makes considerable use of prefabricated sections. Entire multi-deck segments of the hull or superstructure will be built elsewhere in the yard, transported to the building dock or slipway, then lifted into place. This is known as "block construction". The most modern shipyards pre-install equipment, pipes, electrical cables, and any other components within the blocks, to minimize the effort needed to assemble or install components deep within the hull once it is welded together.
Ship design work, also called naval architecture, may be conducted using a ship model basin. Modern ships, since roughly 1940, have been produced almost exclusively of welded steel. Early welded steel ships used steels with inadequate fracture toughness, which resulted in some ships suffering catastrophic brittle fracture structural cracks (see problems of the Liberty ship). Since roughly 1950, specialized steels such as ABS Steels with good properties for ship construction have been used. Although it is commonly accepted that modern steel has eliminated brittle fracture in ships, some controversy still exists.[22] Brittle fracture of modern vessels continues to occur from time to time because grade A and grade B steel of unknown toughness or fracture appearance transition temperature (FATT) in ships' side shells can be less than adequate for all ambient conditions.[23]

Ship repair industry

All ships need maintenance and repairs. A part of these jobs must be carried out under the supervision of the Classification Society. A lot of maintenance is carried out while at sea or in port by ship's staff. However a large number of repair and maintenance works can only be carried out while the ship is out of commercial operation, in a Shiprepair Yard. Prior to undergoing repairs, tankers must dock at a Deballasting Station for completing the tank cleaning operations and pumping ashore its slops (dirty cleaning water and hydrocarbon residues).

  http://en.wikipedia.org/wiki/Shipbuilding