Numerical analyses were performed to calculate the heat transfer and friction factor of a finned-tube heat exchanger used for exhaust gas boiler in ships. The heat exchanger has two main design constraints. The first constraint is velocity lower limit to prevent soot of exhaust gas from being deposited. And the second constraint is permissible pressure loss in order to forbid increase of back-pressure which may lead to a high thermal loading of engine components. Based on those reasons, tubes of the boiler have to be arranged in-line so as to decrease amounts of soot deposition. And the tube-diameter of the boiler has to be larger than that of prevalent finned-tube heat exchanger. In this study, the heat transfer and flow friction factor of the presented finned-tube heat exchanger were correlated using computational fluid dynamics since the existing heat transfer and friction correlations are not valid for such a large tube-diameter with in-line arrangement. Number of tube rows was firstly considered because the exhaust gas boiler has formulaic specification as mentioned earlier. The correlation formulas which were obtained from the computational analyses can be used for further studies such as performance prediction or geometrical optimization.