We have had some requests for this already and are interested to do it, however, it is likely a lot of work and we have too many higher priority things at the moment. Aside from the fact that OpenSeaMap uses more than 300 custom icons which we would probably have to reproduce and then integrate, we would also have to build support for drawing these arcs from the beacons and lighthouses.
After we get the next big release out, we are planning to work on topographic maps and the track recording/waypoint functions. We can look more then at the feasibility of doing marine maps.