electronic charts format

I am thinking of writing my own navigation software.
Not to save money, but just for the fun of it, and
because I would like it to be an "open system" so that
I can easily add features to it from time to time.
I have sorted out the hardware but I am having problems with
the electronic charts. The charts I would need right now
have to cover the Baltic sea.

When trying to find do***entation about the "S-57" format
I only find very "strange" do***entation which is not
very helpful. It is as if someone has made it obscure on
purpose?
  It is very likely that I just haven't found the right
do***entation for this, but the ones I have found like:

IHO TRANSFER STANDARD
for
DIGITAL HYDROGRAPHIC DATA
Edition 3.1 - November 2000
Special Publication No. 57

are not very intuitive, compared to nearly any Internet RFC, which
you just read and then start implementing it ...

Are there any commercially available charts that can be used on a PC.
And to make it clear, I have no intention of cracking any codes and
I am more than happy to pay for these charts and "lock" them to the
computer that I install them on.

And how do you read these charts?

Josce