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Noise emissions from ships can be a significant source of annoyance when residential areas are located near the wharfs where ships are moored. Therefore, it is important to predict harbor noise in order to get an effective environmental noise control. Prevision models apply to several practical cases such as the evaluation of the noise impact in planning new ports, or in widening existing harbor, or in locating new mooring positions. In general, commercial simulation programs allow to carry out noise mapping taking into account road traffic, rail traffic, airport traffic and industrial plants; specific modules are dedicated to such items. Noise from ships, on the contrary, is not usually included in the libraries of these software. To test the reliability of such simulators in predicting noise field from complex sources such as ships, in the present work efforts were devoted to model the airborne noise propagation for two different vessels, a multipurpose ship and a fishing research vessel, using a commercial software and starting from simple source models. The development of the model for both ship types was made in five steps: acquisition of the input data; creation of the ship in the sound propagation software, definition of the noise sources; model validation; output data. Various characterizations of ships as noise sources were considered, including the presence of local and extended noise sources. Simulated data were then compared with measurements on field. The obtained results rise some questions about the measurement techniques adopted to characterize the source levels and the validation data, the simplifications made on the ship surface and the typologies of sources utilized in the study. Future developments in numerical simulators are needed in order to better describe outdoor noise propagation from ships, taking into account the specific nature and complexity of such sources.