Ships sink in ocean tiles

[Gurn]

Hello

I've added some ships in my mod, everything is Ok when they are on coastal tiles, but when they go on ocean tiles, they go down (as if they climb out from a hill), only the smokestasck is still visible.

Any Idea ?

Thanks

EDIT : Found the response in the GEM bug section. http://forums.civfanatics.com/showthread.php?t=494022
Related to a promotion with the <CanMoveImpassable> feature set to true

Sorry for posting (can't delete this thread myself)