Chart Plotting Software
There are a number of free, or relatively cheap, PC-based navigation packages available these days. Chief among them are OpenCPN, SeaClear and two packages by Polar Navy. Each has its merits, so the choice of which to use boils down to personal preference and which operating system your Laptop or Tablet runs.
My personal favourite, OpenCPN is a free chart plotter and navigation software package for use underway or as a planning tool. OpenCPN is developed by a team of active sailors using real world conditions for program testing and refinement. OpenCPN will run on Windows XP to Win 10, Linux, BSD, Solaris and MacOSX. It does not run on Android or IOS (yet). There is an active OpenCPN forum on the Cruisers and Sailing forum where you can seek advice or, if you have the skills, contribute to the program's development.
If you search hard enough you can find CM93 V2 vector charts for OpenCPN available for download from a number of torrent sites. Be careful though, as the title suggests, they are somewhat out of date and torrent sites are good vectors for viruses. As to whether or not it is legal to download them, I don't know. They have been superceded several times (with better encryption), but I dare say someone still owns the copywrite.
SeaClear is a free PC based chart plotting system for Windows. With a GPS connected, SeaClear displays your current position, speed, heading and other data on the screen. The chart scrolls automatically and new charts are loaded before you sail off the edge. Tracks may be saved to file for later reviewing and log book entries can be made manually and automatically. Unlimited number of routes and waypoints can be created and used to assist navigation.
SeaClear makes very efficient use of memory and runs happily on low end laptops and netbook computers. It can even run on Linux based operating systems, eg. Ubuntu, running Windows emulation software such as Wine.
Find out more about SeaClear and download the software: SeaClear.
There is also an active SeaClear users group on Yahoo where the answers to most questions can be found: SeaClear Users Group.
Polar Navy have two packages to offer: PolarView NS, which runs under Windows, Linux or MacOSX operating systems and PolarView MX, which runs on Apple IOS devices. Both are "try before you buy" downloads.
UK Admiralty Charts
Up until recently the only way to import your UKHO Admiralty charts into SeaClear or OpenCPN was by scanning them, usually in sections, and then converting the graphics image into the SeaClear or OpenCPN chart format. The process is both difficult and time-consuming unless you have access to a full-size scanner. Fortunately there is a better way.
If either OpenCPN or Polar Navy are your preferred software package go to Visit My Harbour and order UK Admiralty Charts for OpenCPN or Polar Navy on either DVD or usb dongle.
And if SeaClear is your preferred software package go to Visit My Harbour and order UK Admiralty Charts for SeaClear.
Either one of those packages will give you 400+ full scale, up-to-date Admiralty raster charts, fully licenced for navigation, plus another 400 or so harbour plans and chartlets.
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Sight Reduction Form
Print double sided and on one side you can reduce morning, noon and afternoon sights, while on the reverse you will find a plotting sheet adapted from Andrew Evan's Sextant Users Guide. Ideal for that "Sun-run-Sun" sight. Download.
Universal Plotting Sheet
For the more traditional minded here is a Universal Plotting Sheet to try.