G-class frigate

The G class (Turkish: Gabya sınıfı fırkateyn(ler)) is one of the frigate classes of the Turkish Navy. They are extensively modernized versions of ex-Oliver Hazard Perry-class frigate guided-missile frigates of the US Navy, mainly designed for air defense with a weapons configuration that is optimized for general warfare.

Modernization
The G-class frigates have undergone a major modernization program which included the retrofitting of a Turkish digital combat management system named GENESIS (Gemi Entegre Savaş İdare Sistemi). The system was designed and implemented jointly by the Turkish Navy and HAVELSAN, a Turkish electronic hardware systems and software company. The first GENESIS upgraded ship was delivered in 2007, and the last delivery is scheduled for 2011.

The GENESIS advanced combat management system includes the following characteristics and abilities:
 * A modern and reliable system
 * High performance
 * Open architecture
 * Capacity of tracking more than 1,000 tactical targets
 * Modern digital sensor data fusion
 * Automatic threat evaluation
 * Weapon engagement opportunities
 * Link-16/22 system integration

The modernization program also includes:
 * The addition of an 8-cell Mk-41 VLS for Evolved Sea Sparrow, including the upgrade of the Mk-92 fire control system by Lockheed Martin
 * The retrofitting of a new advanced SMART-S Mk2 3D air search radar to replace AN/SPS-49
 * The addition of a new long range sonar

The Mk-41 vertical launching system (VLS) has been fitted in front of the Mk.13 launcher, similar to their installation on the Adelaide-class frigates of the Royal Australian Navy, which are Australian-built derivatives of the Oliver Hazard Perry-class frigates. TCG Gediz became the first ship in the class to receive the Mk 41 VLS installation.

The "short hull" ex-Perry class frigates that are currently being operated by the Turkish Navy were modified with the ASIST landing platform system at the Istanbul Naval Shipyard, so that they can accommodate the S-70B Seahawk helicopter.

Ships

 * TCG Gaziantep ex-USS Clifton Sprague (FFG-16)
 * TCG Giresun ex-USS Antrim (FFG-20)
 * TCG Gemlik ex-USS Flatley (FFG-21)
 * TCG Gelibolu ex-USS Reid (FFG-30)
 * TCG Gökçeada ex-USS Mahlon S. Tisdale (FFG-27)
 * TCG Gediz ex-USS John A. Moore (FFG-19)
 * TCG Gökova ex-USS Samuel Eliot Morison (FFG-13)
 * TCG Göksu ex-USS Estocin (FFG-15)

In addition the ex-USS Duncan (FFG-10) was sold to the Turkish Navy as a parts hulk