Yes, but what you
can use on
OpenCPN is different from the question of what's
good on
OpenCPN. The OP's question concerns
proper charts, not just
charts. I've just been going through this myself.
For what cruising areas are you looking for charts?
I can share my experience, and what I've recently learned, which is somewhat limited but might give you a start.
First of all, you need to try out and understand the difference between vector and raster charts. I had never used raster charts before a few days ago and this was an eye-opening experience for me. They
work in a totally different way -- in many ways like paper charts. As I was advised by one OpenCPN developer, raster charts show you what a professional cartographer decides should be displayed at a given scale -- not what the machine decides (or you decide, by manipulating the controls). I think for plotting purposes underway, this is not as useful as what you get from vector charts, but for planning on a big
screen might be better. You will need to try for yourself.
Almost everyone starting out with OpenCPN acquires a world-wide set of CM93 vector charts. This makes a terrific base map which allows you to have a look at any waters almost anywhere, on any whim. Unfortunately, the
legal status of these charts is not clear -- they may be pirated and illegal, or maybe in the public domain (according to some people), but you will have to
research and decide yourself whether you think it's right to use them. They are not up to date so should never be used for primary
navigation. But for planning they are really useful, although like other vector charts they can be hard to
work with because detail disappears when you zoom out, making it hard to get the big picture you need for planning. This problem may or may not be fully mitigated by using advanced controls in OpenCPN; something I am still
learning. But for sure, getting the "big picture" is much more straightforward with raster charts.
For U.S. waters, you can get commercial-grade vector charts for free in the S57 format (an unencrypted version of S63). See:
S63 Vector Charts | Official OpenCPN Homepage. (From the same official source (NOAA), you can get free, official raster charts of U.S. waters). I wish the rest of the world would provide cartography like the Americans do. For other areas, S63 charts (which require a
plugin for OpenCPN) are very expensive. For European waters, you actually rent them. People say these are much better quality than our leisure-grade electronic vector charts (Navionics, CMap, CM93); I've not tried them so can't say how much.
For European waters, most if not all electronic cartography
sold for use with leisure sailors' computer
navigation programs (as opposed to dedicated plotters) is raster, not vector cartography. For UK, Irish, Spanish, Belgian, and
Netherlands waters, there is an absolutely fantastic company called visitmyharbour.com, which publishes superb pilotage information on its website, and sells raster charts for the above-mentioned areas at a great
price and on great terms. I've bought UK, Irish, Belgian, and
Netherlands charts from them for 50 pounds ($75), which are up to date and officially "For Navigation", with free updates through the end of 2016. The format is somewhat awkward as the charts come on an encrypted USB stick, which has to be physically present, and which has to be unlocked every time you start up your computer.
For the
Baltic and European Atlantic coasts (and some
Caribbean areas), there is an eccentric German company called NV Charts. They sell folios of raster charts which are supposed to be of superb quality, not derived from official sources like Visitmyharbour, but produced in-house by the company's own cartographers. Unlike Visitmyharbour, whose charts cover huge areas and are
cheap, NV Charts cartography are
sold in relatively small areas and cost a relative fortune. The publishers feel strongly that electronic charting should not be used without paper (contrary to what many on here will tell you), and you cannot buy their electronic charts without their paper ones. The owners of the NV Charts company are
Baltic sailors, and the Baltic is notoriously difficult to sail without paper charts, so this may be the origin of this policy.
There is a site called openseacharts.com which is supposed to give access to a wide variety of free vector and raster charts. I have not figured out how to use it, and would be interested to hear of others' experiences with it.
There are many other sources listed on the OpenCPN site, on this page:
Chart Sources | Official OpenCPN Homepage
It would be great to hear of others' experiences with the various sources.