Introduction

Until a decade ago, PC-based navigation software on board of leisure yachts was not an issue. Computers were not well suited for marine environments, dissipated considerable amounts of electrical power and there were few suitable application for marine navigation. Today (2025), this situation has changed and personal computers are now an integral part of the navigation and monitoring equipment on board of pleasure yachts.

Here are some links to (semi-professional) navigation software tools:

• OpenCPN: A chart plotter and GPS Navigation Software.
  OpenCPN is a free software (GPLv2) project to create a concise chart plotter and navigation software for use as an underway or planning tool. OpenCPN is developed by a team of active sailors using real world conditions for program testing and refinement.
  
  The most recent stable version, OpenCPN 5.12.4, was released in September 2025. It is available for different Linux platforms as well as for MacOSX and Windows. The software package can be downloaded from https://opencpn.org/OpenCPN/info/downloads.html.
  
  OpenCPN is a simple, concise Chart Plotter Navigator. It is designed to be used continuously at the helm station of an underway ship or boat, allowing the operator to easily track their position on accurate chart images. Additionally, OpenCPN can display tide and current predictions, as well as information on other suitably equipped vessels in the area (AIS). It also supports dashboard functionality for on-screen displaying of NMEA0183 data of on-board instruments (e.g. GPS, depth sounder, electronic compass, anemometer).
  
  Notice: It seems to be difficult to find appropriate chart data for OpenCPN. Commercial vendors are selling their electronic nautical maps in a proprietary encoded, platform specific format, that OpenCPN can't handle. This way these chart data suppliers are securing their business model of their own proprietary navigation software and are basically impeding all independent software development efforts such as OpenCPN.

• OpenSeaMap: an open-source project aiming to make high-quality nautical charts freely available. OpenSeamap is part of the OpenStreetMap project and it is a chart option to be used with OpenCPN. However, many features such as the depth profile data, are still in a beta phase.

• Interactive map with Leaflet and OpenSeaMap: This is an javascript-based application using "Leaflet" and "OpenSeaMap", that can be used to do some rudimentary cruise planning.
  It allows to mark waypoints and to plot a track on an OpenSeaMap map. These waypoints can be exported in an extra window, showing the Latitude-Longitude coordinates as well as leg and track distance.
  However, this application can be used only for initial planning and the obtained waypoints and legs MUST be carefully verified on a valid sea chart before they can be used for real-world navigation!