A heat exchanger is a device used to transfer thermal energy (enthalpy) between two or more fluids, at different temperatures. This tube type lubricating oil heat exchanger is used to extract heat from lubricating oil circulating in the main engine of a vessel. Its operation is based on the principle of heat balance, given as: Q=MhCph∆Th = McCpc∆Tc. This heat exchanger was designed using the Logarithmic Mean Temperature Difference method and it takes up sea water at 27 degree celsius and exits it at a temperature of 68 degree celsius. The exchanger has 96 tubes and a shell area of 0.0239 square meter, with an overall heat transfer coefficient of 172.3W/moc and effectiveness of 50.41 percent. The paper shows standard steps to design and analyze the working and performance of a Tube type heat exchanger. By plotting a graph of effectiveness against lubricating oil temperature difference, using the energy balance equation and analyzing same, the maximum possible effectiveness is obtained. The uniqueness of this design is essentially in its mode of operation, simplicity and construction.