Building Mode is the period of time in the game cycle where water is not present on the map and players can safely build ships without fear of being attacked.
It is highly recommended to only build and construct during this period as the threat of being attacked and bombed is great during the Flood. However, building time is short, as it only lasts for 150 seconds. As a final result, combat is totally disabled with ship cannons and players are not equipped with weapons.
During the short time between building mode and the time when guns are able to finally fire, swords can do damage and can kill players.