The Hydrex cannon became a common sight on Human warships ever since the beginning of the Human-Shey war. Smaller ships usually have bow-mounted Hydrex cannons with lower yields of 50-100 Gigatons. Bigger ships (Destroyers, carriers, Battleships, etc.) could carry multiple Hydrex cannons, but generally had one on the bow that was more powerful than the others.
The Hydrex weapons were designed in conjunction by Supertech Industries, the Red Hand, and the Rachneed Corporation, as well as recieving massive funds from the CIA. The first model was introduced in 2330, just in time with the start of the Human-Shey war. The weapon fired a navy blue "laser" at its target. Frigates recieved scaled down versions that would reach out put of 900 Megatons to 75 Gigatons. Cruisers generally had two of these weapons, one on the bow, and one on the belly, for in atmosphere bombardments. The belly mounted cannon could deliver 75 Gigatons of damage, with the bow mounted cannon doing 150 for light cruisers, and 200 for Heavy cruisers.
In 2349, the Red Hand and Supertech released the Hydrex-2, using technology they procured from the Nayam federation. The Hydrex-2 had the same yield for all ship classes: 700 Gigatons per minute.
The Hydrex-2f was the frigate version released a year after the original Hydrex-2. There were many incidents where firing of the Hydrex cannon caused system failures on ships due to its massive energy consumption. Thus, the 2f was introduced. Although it had a smaller yield than the original cannon, 300 Gigatons per minute, it was welcomed by the Navy, as it ws something the frigates could actually accomodate.
The 2d was designed for Destroyers. Some of the lighter destroyers had the same problem as frigates, they could generate enough power to fire the weapon and keep the rest of the ship's systems online at the same time. The 2c was given to all light destroyers and some medium destroyers, and had a yield of 500 Gigatons.
The 2c was the Cruiser version. With newer powerplants being introduced in the year 2351, the Hydrex-2c was released to keep pace with the available power. This one had a slightly improved yield, 750 Gigatons per minute. The major difference was that it only used half as much energy as the original Hydrex-2. All cruisers took the upgrade, and even some Heavy Destroyers were able to recieve it.
The 2b was also released in 2351. At the time of its release, it was the most powerful conventional weapon ever seen, with a yield of 400 Teratons per minute. It was able too achieve such a yield with the help of Cetza scientists and reverse engineered Shey technology.
The Hydrex-3 is the pinnacle of Human weapon's technology. Introduced in 2390, the Hydrex-3 took weapons to the next level. The Battleship versions were the most powerful, capable of 2 Petatons per minute when at full power(Though they were generally fired at 25% power, giving them a yield of 500 teratons per minute). Cruiser versions were doing ten Teratons for light cruisers and 50 Teratons for Heavy cruisers. Light destroyers were doing ten teratons, and Heavy destroyers reaching 20 Teratons. Frigates were still stuck in the Gigaton range at around 900 Gigatons per minute.
The Hydrex-3 series was a huge success, but it wasn't enough to satisfy Humanity's thirst for power. In 2405, the Red Hand developed the Hydrex-3pk on their own. It was a massive project that consumed most of the companies funds, but the payoff was huge. The Hydrex 3-pk was a massive, two kilometer long weapon, capable of dealing an Exaton worth of energy in a minute. However, it needed around 4 exawatts of energy to power the weapon for a full minute. Because of the amount of power require to fire the weapon, and how expensive the weapon was, there was a single ship built solely for the purpose of usig the weapon, the Decimator-class. Other than the Decimator-class, the HRS Nuremburg is the only other ship known to ever field one of these massive weapons.