Flyvefisken-class patrol vessel

P555 HDMS Støren
Class overview
Name	Flyvefisken class
Operators	Royal Danish Navy Lithuanian Naval Force Portuguese Navy
Subclasses	Tejo class (Portugal)
Built	1985–1995
In commission	1989–present
Planned	17
Completed	14
Cancelled	3
Active	9
Retired	1
Preserved	3 (for sale)
General characteristics
Type	Patrol vessel
Displacement	320 tonnes (315 long tons) light 450 tonnes (443 long tons) full load
Length	54 m (177 ft 2 in)
Beam	9 m (29 ft 6 in)
Draught	2.5 m (8 ft 2 in)
Propulsion	Combined diesel and gas 1 × General Electric LM500 gas turbine 4,066 kW (5,453 hp) 2 × MTU 16V 396TB94 diesels 4,226 kW (5,667 hp) total 1 × auxiliary GM 12V-71 diesel, 373 kW (500 hp) hydraulic propulsion 3 × auxiliary GM 6-71 diesel generators
Speed	30 knots (56 km/h; 35 mph) on turbine + diesels 20 knots (37 km/h; 23 mph) on MTU's 7 knots (13 km/h; 8.1 mph) on hydraulic drive
Range	3,860 nmi (7,150 km) at 18 kn (33 km/h; 21 mph)
Complement	19-29 depending on role
Sensors and processing systems	Terma Scanter Mil 009 surveillance radar Thales TMS 2640 Salmon variable depth sonar Furuno navigational radar EADS TRS-3D air search radar (Combat role) Plessey AWS-6 air search radar (MCM role) Saab 9LV 200 Mk 3 Fire control radar
Armament	Armament depends on the ships role, but includes the following options: 8 × launchers for Boeing RGM-84 Harpoon Block II SSM 12 × launchers Sea Sparrow SAM 1 × OTO Melara 76 mm/62 gun 2 × 12.7 mm machine guns 4 × 323 mm (12.7 in) MU90 ASW torpedoes 60 mines

HDMS Viben (P562).

LVS Dzūkas (P12).

The Flyvefisken-class patrol vessels ("Flying fish" in Danish) are warships of the Royal Danish Navy. The class is also known as the Standard Flex 300 or SF300 class. The five vessels sold to the Portuguese Navy are locally referred as Tejo class.

Containerised weapon systems

The Flyvefisken ships were constructed using an innovative modular design known as StanFlex: they have a standard hull in which containerised weapons or systems can be placed. This allows them to rapidly change roles, typically in 48 hours. This enables the ships to be configured to perform the following roles:

• Surveillance/pollution control
• Combat
• Mine countermeasures/minehunter (MCM)
• Minelayer

The containers measure 3.5 by 3 by 2.5 metres (11.5 ft × 9.8 ft × 8.2 ft). One container is situated on the foredeck; the other three go on the quarterdeck behind the superstructure and funnel. Furthermore the ships are built using the sandwich principle - a layer of fiberglass either side of a core of PVC cell foam. This forms the structure from keel to top of mast. This building method reduces maintenance costs - so much so that 20 years later the new Diana and -Holm class have been built using the same materials.

Replaced three different vessels

The Flyvefisken class replaced three different vessels in the Danish Navy: Six torpedo boats of the Søløven class (1965–90), six coastal minesweepers of the Sund class (1955–99) and eight seaward defence craft of the Daphne-class (1961–91). It was possible because of the containerised systems and modern technology.

The replaced vessels used World War II (or World War I) tactics: The Søløven boats were light plywood boats propelled by three turboshafts, which attacked the enemy ships with torpedoes in 54-knot (100 km/h; 62 mph) hit-and-run attacks. The Flyvefisken class is not that fast, but their Harpoon missiles are sufficient for the task.

The Sund-class minesweepers were built of wood, bronze and other non-magnetic materials. They swept mine fields by trawling through the area with paravanes on tow separating magnetic and acoustic generators for the bottom mines, and chain cutters for the horned mines. The Flyvefisken class is a minehunter and locates the mines with side-scan sonar and neutralizes them one by one with a ROV.

The Daphne class attacked submarines by dropping depth charges to a preselected depth, while sailing past the submarine. The Flyvefisken class fights submarines with anti-submarine homing torpedoes.

Vessels in Portuguese Service

Four vessels of the class (Glenten, Ravnen, Skaden and Viben) were acquired by the Portuguese Navy in 2010 and re-named Mondego, Douro, Guadiana and Tejo. A fifth vessel, Gribben, was also acquired by the service as a spare parts hull. After a period of upgrade and reconfiguration, Mondego and Tejo were specifically tasked to police Portugal's exclusive economic zone around Madeira.

In 2023, 13 sailors assigned to Mondego were relieved of their duties when they refused to board the ship claiming her to be unseaworthy. The navy rejected the claim, which was made after the vessel had been tasked to monitor a Russian ship sailing in the vicinity of Madeira.

Ships in class

A total of 14 ships were built in the class, in three series:

#	Name	Laid down	Launched	Commissioned	Decommissioned	Int. Callsign	Role
Series 1
P550	Flyvefisken (Flying fish)	15 August 1985	26 April 1986	19 December 1989	Sold to Lithuania, March 2007 - LVS Žemaitis (P 11)	OVDA	MCM
P551	Hajen (Shark)	February 1988	6 August 1989	19 August 1990	Sold to Lithuania, March 2007 - LVS Dzūkas (P 12)	OVDB	MCM
P552	Havkatten (Catfish)	August 1988	13 January 1990	1 November 1990	12 January 2012 - Sold to Lithuania, 23 November 2016 - LVS Sėlis (P 15)	OVDC	MCM
P553	Laxen (Salmon)	March 1988	20 May 1990	12 March 1991	7 October 2010	OVDD	MCM
P554	Makrelen (Mackerel)	December 1988	8 January 1991	4 October 1991	7 October 2010	OVDE	MCM
P555	Støren (Sturgeon)	August 1989	1 September 1991	24 April 1992	7 October 2010	OVBF	MCM
P556	Sværdfisken (Swordfish)	-	1 September 1991	1 February 1992	2 August 2006, scrapped	OVDG	MCM
Series 2
P557	Glenten (Kite)	-	1992	1 February 1992	7 October 2010 Sold to Portugal, October 2014 - NRP Mondego (P 592)	OVDH	Combat
P558	Gribben (Vulture)	-	1992	1 July 1993	7 October 2010 Sold to Portugal, October 2014 - as spare parts hull	OVDI	Surveillance
P559	Lommen (Loon)	-	1993	21 January 1994	Sold to Lithuania, March 2007 - LVS Aukštaitis (P 14)	OVDJ	Surveillance
P560	Ravnen (Raven)	-	1994	7 October 1994	7 October 2010 Sold to Portugal, October 2014 - NRP Douro (P 591)	OVDK	Combat
P561	Skaden (European magpie)	-	1994	10 April 1995	7 October 2010 Sold to Portugal, October 2014 - NRP Guadiana (P 593)	OVDL	Combat
P562	Viben (Northern lapwing)	-	1995	15 January 1996	7 October 2010 Sold to Portugal, October 2014 - NRP Tejo (P 590)	OVDM	Combat
Series 3
P563 Y311	Søløven (Sea lion)	-	1995	27 May 1996	-	OVDN	Surveillance Diving support from 2012

The difference between the series is mainly in the configuration of the propulsion system. Series 2 is not equipped with hydraulic propulsion, but instead has an additional auxiliary engine, and Series 3 has one further auxiliary engine.

External links

• Danish Naval History
• Naval technology on Flyvefisken class