In traditional approach to position fixing navigator exploits available uncertain measurements and various systems indications. Thanks to the nautical knowledge position is fixed and evaluated. Final results are rather intuitive than proved by limited data processing [7]. Mathematical apparatus based on probability theory and series of assumptions is not flexible enough to include knowledge and ignorance into position fixing calculation scheme. Limited ability is available regarding fix accuracy evaluation. In the paper Mathematical Theory of Evidence is exploited in order to extend foundations for implementation of new approaches. The theory extended for fuzzy environment creates new opportunities enabling modeling and solving problems with uncertainty [2], [3], [17]. Concept of using the new basement for position fixing was presented by the author in his previous publications. Herein comprehensive introduction to the platform is presented, moreover evidence assignment transformation is depicted in context of solving position fixing problem.