The French and the Italians share the Horizon-class stealth-minded guided-missile frigate design. In the former, these are the "Forbin" and the "Chevalier Paul" while, in the latter, these comprise the "Andrea Dorio" and the "Caio Duilio" (the subject of this article). While DCNS Lorient handled construction of the French warships, several local Italian shipyards were part of the Marina Militare's building effort where the class is further differentiated as the Orizzonte-class. As air defense destroyers, their primary ocean-going role is in airspace denial and neutralization of inbound aerial targets. They can also serve as command and control ships, hunt enemy submarines, and deal with ranged surface threats due to their weapon balance.
NOTE: Some sources will classify the Horizon-class ships as guided-missile frigates.
Caio Duilio was ordered for the Italian Navy on October 27th, 2000 and saw her keel laid down by Italian shipbuilding industry on September 19th, 2003. She was put out to sea on October 23rd, 2007 and was formally commissioned for service on April 3rd, 2009. She homeports out of La Spezia along the upper West coast of the Italian boot and fights under the motto of "Nomen Numen". As of April 2018, she remains in active service.
As built, the warship displaces 7,770 tons under full load and has an overall length of 501.5 feet, a beam of 66.6 feet, and a draught of 24.9 feet. A fuel-efficient COmbined Diesel-Or-Gas (CODOG) arrangement is used for power that consists of 4 x Avio (General Electric) LM2500 gas turbines and 2 x SEMT-Pielstick 12 PA6 STC marine diesel engines driving 2 x Shafts astern. 1 x Bow thruster is also fitted for precision maneuvering and there is additional power from 2 x Power stations and 4 x Isotta Fraschini VL1716T2ME diesel generators. Maximum speed (under full gas turbine power) in ideal conditions reaches 29 knots and cruising (under the diesel marine units) is about 18 knots. Range is out to 7,000 nautical miles when heading consistently under 18 knots.
The warship carries supplies for up to 45 days at sea and has full crew accommodations for up to 255 personnel made up of officers, petty officers, and enlisted candidates. A typical crew is around 230 and this includes a modest air arm as well as various security personnel. Installed systems run the gamut of modern and advanced sensors and processing components comprised of the Selex RAN 30Z/I (RASS) E/F-band surface-search radar, the Selex SPY-790 (EMPAR) muti-function 3D phased radar (G-band), and the Thales/Selex S1850M D-band long-range 3D radar suite. The SLQ-750 makes up the ESM fit and the Nettuno 4100 series unit handles the Electronic Warfare (EW) section. Radar jammers, an anti-torpedo system, and chaff/flare launchers round out the long list of systems found aboard.
Armament is a mix of projectile-based and missile-based weapons. There are 3 x 76mm OTO-Melara "Super Rapid " turreted main guns carried along with 2 x 25mm /80 caliber OTO-Melara (Oerlikon) autocannons. 2 x EuroTorp torpedo launchers handle a stock of MU90 lightweight torpedoes. The heart of this craft, however, is its DCNS "Sylver" A50, a 48-cell Vertical Launch System (VLS) housing either MBDA "Aster 15" or the longer-range MBDA "Aster 30" surface-to-air missiles (and additional sixteen cells are supported as needed). 8 x S/S Teseo Mk2/A missile launchers are also present. In 2017, a pair of SITEP LRAD MASS CS-424 acoustic guns were fitted to combat specialized threats to the ship.
The combination hangar/helo-deck set over the stern can launch and retrieve a medium-lift helicopter, typically the AgustaWestland AW101 or NHIndustries NH90 is seen. These helicopters can be utilized in the at-sea resupply role or modified to serve as Search and Rescue (SAR) or submarine/anti-ship platforms as needed, broadening the tactical value of the vessel.
Caio Duilio's profile exhibits many physical features consistent with modern ship design: an unbroken, full-length bow line, slab-sided panels, enclosed primary structures, etc... The smoke funnels are concentrated near midships and are fully-enclosed with a low-profile design approach used. The main mast, also wholly enclosed, sits atop the bridge superstructure while a secondary mast is set at midships with a third, shorter, mast set over the aft superstructure section. The flightdeck with its attached hangar facilities make up the stern section.
After acceptance into service in 2009, Caio Duilio joined her Horizon-class sisters (including the French twins) for joint exercises - the first time the quad were together in any one place. From there she participated in several celebratory actions and voyages during 2010 and into 2011. In the latter, she also partook in "Proud Manta 2011" which involved other NATO ocean-going elements. While managing a rather low-key, uneventful existence to date, the warship is wholly outfitted to undertake many roles for the Italian Navy including counter-piracy sorties, humanitarian/disaster relief, and convoy/battlegroup escort.