Analysis stability and loads of the tanker in damaged condition

Povećanjem broja tankera koji plove Jadranom, povećava se i opasnost od pomorskih nesreća. Izlijevanje nafte u Jadranu uzrokovalo bi nepopravljivu štetu za okoliš, turizam i gospodarstvo. Zbog toga je pokrenut projekt Structural reliability of damaged oil tanker in Adriatic Sea koji za cilj ima predložiti metodologiju procjene sigurnosti strukture oštećenog tankera za prijevoz nafte u Jadranskom moru i postaviti proceduru za racionalno donošenje odluka za brod u situacijama koje traže hitne reakcije. U ovom radu je pomoću programa GHS izvršen proračun stabiliteta i uzdužne čvrstoće za tanker u oštećenom stanju, u skladu s posebnim pravilima koja propisuju klasifikacijska društva. Za homogeno, potpuno natovaren tanker modelirano je 21 stanje oštećenja. Za svako stanje oštećenja dan je prikaz prostora i karakterističnih krivulja stabiliteta i uzdužne čvrstoće. Dobiveni rezultati uspoređeni su sa propisima i rezultatima proračuna za neoštećeno stanje. Pokazalo se da tanker u svim stanjima oštećenja zadovoljava kriterije stabiliteta, i to uz veliku rezervu. Najveći momenti savijanja variraju od smanjenja za 68.3% do povećanja od 52.47% u odnosu na neoštećeno stanje. Nedostatak podataka za moment otpora u oštećenom stanju onemogućuje stvaran uvid u opasnost povećanja opterećenja uslijed naplave. Balastiranjem se može pokušati smanjiti opterećenja, ali se to nije pokazalo uvijek kao učinkovito i sigurno rješenje.By increasing the number of tankers in the Adriatic Sea, the hazard of maritime accidents increases as well. Oil spillage in the Adriatic Sea would cause unrecoverable damage to the environment, tourism and economy. Hence the project Structural reliability of damaged oil tanker in the Adriatic Sea was initiated, with the aim to propose methodology of structural safety assessment of a damaged oil tanker in the Adriatic Sea and to set up a procedure for rational decision making for a ship in the situations requiring emergency response actions. Calculations of damage stability and longitudinal strength were made within this paper. Classification societies provide special rules for damage stability. 21 damage cases were modeled for a homogenous, fully loaded tanker. For each one of them a compartment plan and characteristic stability and longitudinal length curves were shown. The obtained results were compared to classification society rules and results for the undamaged tanker. It was shown that the tanker meets all the stability requirements, with a great margin. Maximum bending moments vary from a decrease by 68.3% to an increase by 52.47%, compared to the value in undamaged condition. Lack of information about section modulus in damaged conditions makes it impossible to get the real insight in the danger of load increase due to flooding. One way of attempting to decrease load is ballasting, but it has not always proven to be an efficient and safe solution