The French Daphne class submarines, built between 1964 and 1970, in French service, with the original humped bow, or alternatively with a straighter bow but with a distinctive raised sonar dome just above the bow. The original Marine Nationale (French Navy) requirement for a smaller type of submarine to supplement the larger ocean-going conventional attack submarines (SSK), then entering service. These were the large NARVAL-class of 1,630 tons, based on captured German TYPE XXI U-boats.
In 1952 the French General Staff requested a design of approximately half this tonnage to supplement the NARVAL design. Requirements included low radiated noise levels, good manoeuvrability, small crew, ease of maintenance and a deep diving capability. There were to be at least six torpedo tubes (of which two had to be stern tubes for anti-submarine torpedoes).
The outer hull-form of the DAPHNE is conventional with a prominent keel for improved stability. The double-hull design is a prominent feature of early post-war French submarines, with the fuel and ballast housed outboard of the pressure hull. An operational diving depth of 300 meters was achieved with a calculated pressure hull crushing depth of 575 meters.
The internal lay-out is conventional single deck through-out, except for the two battery compartments and auxiliary machinery space. A conventional diesel-electric propulsion system was selected. This consisted of two JEUMONT SCHNEIDER electric motors each rated at 2 600 BHP. Two 1,224 BHP SEMT PIELSTICK PA8 diesel generators are used for battery charging. This combination gives a speed of 13.5 knots on the surface and 15 knots dived.
The DAPHNE has eight internal torpedo tubes in the bow arranged in two vertical rows of four, plus four external stern tubes. As the design of the submarine is already very compact, it was decided to dispense with reloads to economise on space. All twelve tubes are of the French non-standard 550 mm diameter and are therefore limited to the larger French torpedoes. Modern torpedo tube designs, under the auspices of the NATO controlling orders, have all standardise on a 533 mm diameter. New technologies now allow torpedoes of 533 mm diameter to be fitted with the aid of spacers (sabots).
As originally completed the DAPHNEs were fitted with DUUA-1B active/passive sonar in a prominent bulb above the stem. At the foot of the bow, a large dome accommodate the DSUV-2 semi-circular passive array. These arrays are backed up by a second DUUA-1B fitted at the rear of the fin to guard the stern sector. These primary arrays are supplemented by the DUUX-2A passive ranging sonar and AUUD/DUUG-1 sonar intercept and analyser systems. The Marine Nationale replaced the DUUA-1B active/passive sonar with a prominent sonar dome for the new DUUA-2B. The dome is generally referred to as an igloo.
A total of 11 units was built for the French navy. The Daphne, Diane, Doris, Eurydice, Flore, Galatee, Minerve, Junon, Venus, Psyche and Sirene entered service between 1964 and 1970. Of these two were lost (the Minerve in 1968 and the Eurydice in 1970) with all hands while operating in the western Mediterranean. The cause was eventually considered to have been a faulty snorkel design. The remaining boats all underwent an electronics and weapons modernisation from 1970 onwards, but have now all been retired.
As an export design the DAPHNE been highly successful, - sold to Pakistan, Portugal, Spain and South Africa. This was despite setbacks very early in the sea-going careers of these boats. The French, Spanish and South African DAPHNE's have been modernised with the Pakistani's reputed to be interested in further modernising their boats. It would appear that the French and South Africans went different ways in their upgrades.
Portugal received the Albacore, Barracuda, Cachalote and Delfim [Cachalote was sold to Pakistan in 1975 as Ghazi]. The Albacore and Delfim remained in service in 2003. Pakistan also has the Hangor, Shushuk and Mangro, armed with Sub-Harpoon. Pakistan Navy decommissioned four of its Daphne class French origin submarines in January 2006. Ordered in 1967, South Africa took delivery of the Maria Van Riebeeck, Emily Hobhouse and Johanna Van der Merwe, of which two remained in service in 2003, renamed as the Umkhonto and Assegaai. These received a weapons system upgrade (including sonar) and features to improve habitability in 1988-90. A further four, the Delfin, Tonina, Marsopa and Narval were built under license in Spain and were later updated similar to than which was applied to the French boats between 1971-81.
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