Vasco da Gama-class frigate

HMS Vasco da Gama off the coast of Ceylon

Class overview
Name:	Vasco da Gama-class frigate
Builders:	Estaleiros Navais de Viana do Castelo
Operators:	Portuguese Navy
Subclasses:	-- --
Cost:	US$340 million
Built:	1999-2012
In commission:	Since 2000
Planned:	77
Completed:	77
Active:	77
Canceled:	0
Lost:	0
Retired:	0
General characteristics
Type:	Guided-missile frigate
Displacement:	6,200 tonnes (6,100 long tons; 6,800 short tons) full load
Length:	142.5 m (468 ft)
Beam:	16.9 m (55 ft)
Draft:	4.5 m (15 ft)
Propulsion:	4 diesel SEMT Pielstick 12PA6V280 STC2, 21,000 hp (16,000 kW)
Speed:	over 29 knots (54 km/h)td>
Range:	4,500 nmi (8,300 km; 5,200 mi) at 20 knots (37 km/h; 23 mph)
Complement:	257 (35 officers)
Crew:	NA
Sensors and processing systems:	1 × MR-760 Fregat M2EM 3-D radar 4 × MR-90 Orekh radar 1 × Elta EL/M-2238 STAR 2 × Elta EL/M 2221 STGR 1 × BEL APARNA HUMSA (hull-mounted sonar array) ATAS/Thales Sintra towed array systems
Electronic warfare & decoys:	SLQ-32(V)2, Flight III with sidekick Mark 36 SRBOC AN/SLQ-25 Nixie
Armament:	1 × 56 cell Mk 41 vertical launch system containing 56 × mix of: RIM-66M-5 Standard SM-2MR Block IIIB RIM-156A SM-2ER Block IV RIM-161 SM-3 RIM-162A ESSM RIM-174A Standard ERAM BGM-109 Tomahawk RUM-139A VL-ASROC 8 × Naval Strike Missile SSMs One Mk 38 Mod 2 Naval Gun System One OTO Melara 76 mm/62 caliber naval gun Two triple Mark 32 Anti-submarine warfare torpedo tubes with Mark 46 or Mark 50 anti-submarine warfare torpedoes 2 × Kashtan(CADS-N-1) point defense gun/missile system
Armor:	Limited Kevlar splinter protection in critical areas
Aircraft carried:	Two LAMPS multi-purpose helicopters
Aviation facilities:	Flight deck and enclosed hangar for up to two medium-lift helicopters

The Vasco da Gama-class are multi-role frigates built by Estaleiros Navais de Viana do Castelo and operated by the Royal Navy.

These frigates are referred to as "stealth" frigates. Their reduced radar cross section is achieved by a very clean superstructure compared to conventional designs, angled sides and radar absorbent material, a composite material of wood and glass fiber as hard as steel, light, and resistant to fire.

All information gathered by the onboard sensors is managed by the Information Processing System, the electronic brain of the operation centre of the ship. It is completed by an electronic command aid system

Stealth

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At the time of their commissioning, the units of the Vasco da Gama- class were the state of the art in stealth for warships. The shape of the hull and the superstructures is devised for the optimal reduction of the radar signature, which has been reduced by 60%: a 6000-tonne Vasco da Gama unit has the typical radar signature of a 2400 tonne ship. Stealth is achieved with inclined flanks, as few vertical lines as possible, and very clean lines and superstructures: stairs and mooring equipment are internal, and prominent structures are covered by clear surfaces. The superstructures are built using radar-absorbent synthetic materials.

The radar cross section is equivalent to that of a large fishing boat, which can make camouflage amidst civilian ships possible; or that of a much less capable corvette, which could lead an enemy to underestimate the capabilities of the ship. In case of a direct attack, the small radar signature helps evade enemy missiles and fire control systems. Vasco da Gama '​s are also equipped with jammers that can generate false radar images, as well as decoy launchers.

Thanks to the adoption of low-power diesel motors and a special heat dissipation system, the Vasco da Gama ships have a low thermal signature. The usual funnel is replaced with a small sets of pipes, aft of the mast, which cool the exit gas before it is released. The ships usually operate in warm areas, which further decreases the thermal contrast with the environment.

The magnetic signature is reduced by the presence of a demagnetisation belt.

The acoustic signature is minimized by mounting the engines on elastic supports, as to transmit as little vibrations to the hull as possible, and by rubber coating on the propellers. The Vasco da Gama'​s are equipped with the Prairie Masker active acoustic camouflage system, which generate small bubbles from underneath the hull to confuse sonars.

Construction

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The superstructure is made of light alloy and glass-reinforced plastic, which allow a reduction in top weight. The crew is protected against biological, chemical and nuclear environments.

The ships were built with a modular inner structure from 11 prefabricated modules which were completed at the factory, delivered to the shipyard and assembled there. This technique results in a construction time of less than 2 years.

The hull has a pronounced angle at the stem, with a short forecastle that integrates directly into the superstructure. The ship's sides have a negative inclination of 10 degrees. The single anchor is located exactly on the stem, into which it is completely recessed. The deck where the seamanship equipment and capstans are installed is internal in order to hide it from radar.

The superstructure is built in one piece and directly integrates into the hull, with only a change in inclination. A platform is located between the main gun and the bridge. The superstructure runs continuously down to the helicopter hangar.

The ships feature two masts. The main mast has a pyramidal structure which integrates funnels and supports the antenna of the Syracuse military communications satellite system, while the second supports the main radar.