This paper presents the hull-to-hull (H2H) project where the concept of hull to hull positioning and uncertainty zones are used to assist navigators and operators to perform safe navigation of objects in proximity to each other. Data from position sensors and geometry (2D/3D) data will be shared amongst the H2H objects to calculate for example hull to hull distance to help avoiding physical contact (e.g. steel-to-steel contact). H2H will utilize a variety of positioning sensors, including the European GNSS systems Galileo and EGNOS. The H2H project aims to develop open interfaces such that any H2H compliant equipment provider or user can use the services provided in the planned standard. Data exchange protocols will be based on existing standards as the IHO S-100 standard for geometry and zone descriptions and for describing additional layers needed for ECDIS. Finally, a working methodology describing the needed steps from use case descriptions to implementation of the necessary services is presented.