The Al alloy is environmental friendly, easy to recycle, and provides a high added value to fishing boats. Aluminum alloy do not corrode due to the formation of an anticorrosive passive film, such as Al2O3or Al2O33H2O, which resists corrosion in neutral solution. In seawater, however, Cl-ions destroy this passive film. We investigated on several electrochemical tests undertaken to determine the optimum conditions in seawater for corrosion protection of casted AC7AV aluminum alloy. The components of casted AC7AV aluminum alloy are similar with Al-Mg alloys (5xxx series) which are used for ship. Result of electochemical experiment, the optimum protection potential range with regards to hydrogen embrittlement and stress corrosion cracking was determined to lie between-1.3 and-0.7 V(vs Ag/AgCl).