Hey Lars,
Your are discovering what we all eventually find out about proprietary
map formats.

The thing that is closest to what you want to do is made by Fugawi.
You can scan in maps, calibrate them and then use a pc hooked to a gps
receiver. Admittedly, you have to be a bit of nerd to do it but the
results are nice in that what you have on paper is exactly what you see
on the pc or PDA screen.

They also have the feature of downloading the maps to fugawi software
running on a PDA. I use that feature a lot on old PalmIIIxe. The
newer PDAs with high res color and bluetooth wireless for the GPS
receiver makes a nice combination as well. All it takes is $.

Yes, we need one of the major chartplotter to break ranks. Lowrance
uses the argument that their compression technology is so good that
they can't disclose it. That's not really a valid argument anymore now
that flash memory has gotten so cheap.

Have fun.

Don