In our AAA games we have a coastal artillery rule, but its quite a bit more limited:
“Shore Guns:
Coastal artillery was largely outmoded during WWII, except in the 5 territories underlined below. Ownership of these units depends upon the ownership of the territory, as they cannot be moved. When passing between the sea zones: 12 &13 (Gibraltar), 15 & 16 (Turkey), 5 & 6 (Norway), 6 & 7 (United Kingdom & Northwestern Europe), all enemy naval units except submarines, must endure 1 cycle of fire from Anti-ship guns located in the above territories. Coastal Artillery units attack as Antiaircraft guns, but count as 2 hits to Battleships. Once a territory with coastal artillery is successfully invaded, the shore guns are destroyed.”
Our rules on them are based on the assumption they’re taken out before/during an amphibious invasion. Granted, the above is more for simplicity’s sake yet adding some flavor. This also goes with the rest of our AAA House rules
( http://www.axisandallies.org/forums/index.php?topic=20025.90 ), not too sure how it would perform with Global. :-) And BTW, the coastal artillery FMG sells for the game Singapore 1942 are excellent representations…