Apparatus and methods for routing

A method of automatically developing a marine route in an electronic route developer, comprising:

• an electronic marine route developer employing measured water depth information to develop marine navigational routes;
• and
• a user interface accepting user input regarding a waypoint of a marine route, wherein the electronic route developer:
• determines whether a user-supplied waypoint is a point of navigability;
• and
• automatically develops a marine route based upon a user-supplied non-navigable waypoint, wherein the electronic marine route developer employs water depth measurements to determine a navigable waypoint for substitution in the route in lieu of the non-navigable waypoint, wherein the navigational route developer automatically develops a marine route by discretizing into uniform square discretized cells a multidimensional region that encompasses start and end waypoints with nodes placed in cells, each node connected with its neighbors, and develops a marine route that includes at least one intervening waypoint when the end waypoint and start waypoint are not points of navigable visibility to one another, wherein the electronic router includes water depth measurements in a determination of navigable visibility.