Increasing the Thunderbolt ability will increase the overall damage it does. Additionally, damage levels can also be increased by using Open Fire, Barrage and Cannon Rams. Thunderbolt rounds are only mildly effective against ships masts and sails.
However, it can cause considerable hull damage.
To use Thunderbolt, be stationed at a cannon and press 5 or click the icon at the bottom of the screen. Once one round has been fired, it will take several seconds to reload. You can improve your reload speed by using the Passive Skill Rapid Reload.
Below is a table of Cannon Damage for Thunderbolt:
|1||474 to 948|
|2||593 to 1185|
|3||712 to 1423|
|4||830 to 1660|
|5||949 to 1897|
|*Only with Cannon Ram Boost|
|6*||1083 to 2165|
- Please note damage ranges listed are before any additional damage bonus, i.e. Barrage.
With Ship Customization, when pirates reach Rank 4 Hull Upgrades, they can choose between 5 different upgrades. One of these upgrades is the Storm Chaser Upgrade, which gives the ship a 15% chance of a cannonball fired out of a broadside, to be Thunderbolt. If a pirate chooses to progress to Rank 5 or 6, they will have an even higher chance of Thunderbolt broadsides.
The sheer range of this round makes it very effective at engaging and doing large amounts of damage while being out of range of enemy counter-fire. Many pirates will use this round to damage a ship's masts from a distance before closing in.
Several Skeleton enemy ships also use this cannon ammunition, such as the Phantom, Storm Reaper, Death Omen ships. Spanish Undead and French Undead fleets are also known to use this cannonball. Additionally, the En-Garde is the only Navy ship known to use this ammunition.