Ship hull form modeling is currently a time-consuming task, due to the limited capabilities of the underlying surface representation. Tensor-product B-splines are almost exclusively used in this field, but are limited to four-sided surfaces, which in general does not allow to represent complex surfaces such as ship hull forms easily. This thesis introduces generalized B-spline surfaces to overcome the limitation of B-splines to four-sided surfaces and shows how hull form modeling is simplified and quality of results improved based on this surface representation.