Look at the following example. Boats on d4, d5, e5. A boat on g7 moves to e5. When the boat on g7 moves to e5, then it takes the other three boats with this move. This special case is unlikely to happen.
Promotion rules Promotion rules are complicated.
On a2, a7, b1, b8, g1, g8, h2, h7, a pawn promotes to knight. On a3, a6, c1, c8, f1, f8, h3, h6, a pawn promotes to rook. On a4, a5, d1, d8, e1, e8, h4, h5, a pawn promotes to king. However, when a player owns three or four pawns, a pawn may not promote. Also, when a player has one or two pawns, he may promote to knight and rook.