The lack of a supporting decision tool in submarine pipeline launching activity inspired this work, which intends to provide a quantitative measure about the risks involved in this kind of job. This tool uses Graphs, Fuzzy logic, AHP (Analytic Hierarchy Process) and the help of many experienced professionals to achieve this goal. The Theory of Graphs (Euler, 1736) studies the relationship between objects in a specific mathematical set and has a fundamental unity which is composed by a structure of nodes that interconnect the objects through their edges, the so called Graph. Nowadays, the graphs are used to model real spatial distributions in a computational environment in order to solve routing problems, network flows and flowing streams of any kind. The Fuzzy Logic is able to deal with uncertainty better than Crispy logic, bringing more confidence in supporting decisions regarding subjective issues. Fuzzy Inference Systems are supporting decision making in many areas. This project uses graphs abstraction and Fuzzy Inference System in Submarine Engineering scope to aid in the marine pipelines' route selecting problem. The area where the pipe will be placed is surveyed with acoustic geophysical methods as bathymetry, side-scan sonar and sub-bottom profilers. These resultant maps are then interpreted using the risk classification developed in this work and the gridded area is related to a graph, where each graph node represents a grid node, and a graph edge represents the path between two adjacent nodes with a specific weight. The object of interest of this project is the method responsible for the weight input (risks magnitudes) into graph's edges based on a Fuzzy Inference System. The Fuzzy Inference System uses AHP and a compilation of many specialists' opinions. These opinions were collected from pipeline engineers with many years of experience. They went through an online questionnaire about several factors that represent risks to pipelines such as tectonic zones, faulting, subsurface gases, different types of ocean floor, and marine physiographic features, presence of garbage, areas susceptible to freezing and domains taken by other submarine facilities. Once each graph's edge has the weight given by the risk magnitude the safer path can be calculate by the shortest path algorithm. This work is based on a methodology which was applied in many Civil engineering construction projects. This new methodology coded in Java® programing language resulted in a Software called MAPIRA (Marine Pipeline Risk Assessment), a support decision tool that intends to aid marine pipeline launching professionals. It uses GeoTools® libraries (Since 2006 in OSGeo Project) and brings a way to solve the safer path problem to marine pipelines installation and providing a quantitative measure about the risks marine pipelines could face.