Help with Island Problem


i`m drawing a new coastline following the FSX KML Tutorial and so far everything worked great except that i always have a "land" border around my island like depicted on the screenshots. I understand that the new Hydro Poly needs to be exactly the size of the QMID grid but i`m just unable to find out how to get the exact corner coordinates for the grid. I have been trying it since two days to get rid of that border but to no avail.
I hope someone here could explain to me how i can remove that border.


I`m now at this point as shown below but the border is still visible unfortunately:

best regards
Manuel Seiwald
Now i feel really silly hehe :)

That indeed worked, thank you very much.
I was thinking that this would remove the islands from the other grid cells so thats why i didnt try it.