The board is like a chess board but 9 x 9 instead of 8 x 8. This is really a Draughts variant. All pieces start on the black squares and cannot jump or move on to a white square. One player is the Attack and the other the Defence. Pieces are assigned as sea-going vessels such as a Battleship, a U-Boat and even a Sea Plane. The object for the Attack player is to capture as many vessels as possible. The pieces are assigned a point value. The Defence tries to get as many vessels into a Harbour square, where they are safe from attack.