diff --git a/src/ai/api/ai_marine.cpp b/src/ai/api/ai_marine.cpp
--- a/src/ai/api/ai_marine.cpp
+++ b/src/ai/api/ai_marine.cpp
@@ -54,7 +54,7 @@
 	DiagDirection to_other_tile = ::DiagdirBetweenTiles(t1, t2);
 
 	/* Determine the reachable tracks from the shared edge */
-	TrackBits gtts2 = ::TrackStatusToTrackBits(::GetTileTrackStatus(t2, TRANSPORT_WATER, 0, to_other_tile)) & ::DiagdirReachesTracks(to_other_tile);
+	TrackBits gtts2 = ::TrackStatusToTrackBits(::GetTileTrackStatus(t2, TRANSPORT_WATER, 0, ::ReverseDiagDir(to_other_tile))) & ::DiagdirReachesTracks(to_other_tile);
 	if (gtts2 == TRACK_BIT_NONE) return false;
 
 	to_other_tile = ReverseDiagDir(to_other_tile);