Firing Arcs can take some getting used to in Leviathans as it is:
Be sure to consult the Commanders Manual for the rules on when to use which Arcs
2 Hex Base
3 Hex Base
The Arcs on the 3 Hex Base are measured the same as the 2 Hex Base.
Below is shown how to measure the instance where only Bow guns may fire. This is much more rare in Hex-less play because of the more analog nature of movement.
4 Hex Base
4 Hex Bases have many different Arcs. This can be confusing at first. However, These complicated Arcs only come into play when firing turreted guns from the 4 Hex Base. When firing non-turret guns the basic Arcs are used as with the 2 and 3 Hex Bases. In addition, the same simple Arcs are used when determining the Damage Arc from incoming fire. [The attacker may choose which broadside location is rolled against]