Every unit has its own move range and attack range. After moving a ship within its range you can attack the enemy if it's nearby. As soon as you've made your moves, the enemy takes over and performs a counter attack. Every attack is computed that way: Beside the attack points there are some more things which are calculated in. There are critical hits (1% probability) as well as misses. Plus there are combinations where the attacking ship makes only a damage of 50%. The following list shows the main targets where a damage of 100% will be made (attacker -> targets): CV (Carrier vessel) -> DD, CA, CL BB (Battleship) -> CV, BB, CA, CL CA (Cruiser) -> CL, BB, CV, DD CL (Light Cruiser) -> DD, PT DD (Destroyer) -> SS, PT SS (Submarine) -> CV, BB, CA, CL PT (Patrol Boat) -> SS, CV