Hi all,
I was reading this thread and thought how easy it would be to get better details, like Lat & Longs for the area's needed by using a simple App on a smartphone.
I use Navionics UK & Holland App from my Android Galaxy SII and the details on there would be spot on for your needs, as it gives Lat & Longs, along with detials of the bouy or marker on a chart.
Hope this helps out?
Let me know.