Revealed: Turkey's secret Italian SDV
CE4F article originally posted 22nd July 2016. Info on Turkey added 29th Jan 2017

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Cos.Mo.S CE4F 4-man SDV
Photo from Yildiz Teknik University website

Flag Flag The CE4F was the last and most secret Swimmer Delivery Vehicle (SDV) built by the famed manufacturer Cos.Mo.S based in Livorno, Italy. Within naval circles Cos.Mo.S were well known for their CE2F two-man chariots which were widely exported from the 1960s until ~2000. Sales brochures and photographs of the CE2F were widely distributed and many books discussed them as the classic Cold War western SDV alongside the SEALs’ SDV Mk8. The follow-on CE4F however was barely reported: the original customer, and only known operator, was the Turkish SAT (Su Altı Taarruz) Special Forces. It is only in Jan 2017 that the existence of the SAT version has been made public when an example was given to Yildiz Teknik University (WEBSITE).

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The CE4F was designed for the Turkish Navy's elite Special Forces SAT (Su Altı Taarruz) which is generally equivalent to the US Navy SEALs and has a history of using Cos.Mo.S submersibles. The new craft had to be non-magnetic with a relatively up to date electronics fit including internal navigation, obstacle avoidance sonar, autopilot and folding optronics mast.

Cos.Mo.S CE4F 4-man SDV
Photo from Yildiz Teknik University. Note the mini-torpedo tubes just visible in the nose. The streamlined torpedo tube outer cover is missing.

In building an up-to-date four-man SDV, Cos.Mos.S deviated from the classic in-line crew arrangement of their earlier designs. At first glance the smooth lines of the craft resembled the prototypical US made SDV Mk.8, but the more torpedo-like with a circular cross-section and ducted prop at the rear. It was actually similar in dimensions to the previous generation CE2F except in width, which would potentially allow it to be carried externally by midget submarines in a similar manner to the two-man chariots.
Cos.Mo.S CE4F 4-man SDV
The divers sat in a 2 x 2 layout, all facing forward like in a car. It was not entirely new however; the battery compartment, which was buried inside the streamlined GRP (glass reinforced plastic) fuselage, was actually very similar to the one in the older CE2F. But the major similarities ended there. The layout was unique among SDVs, with the battery compartment and variable stores (mines, torpedoes, Special Forces stores) in the nose, and the crew almost at the back of the craft.
Cos.Mo.S CE4F 4-man SDV
Photo from Yildiz Teknik University website

Length: 8.55m (28ft)
Beam: 1.422m (4.6ft)
Height: 1.475m (4.6ft)
Displacement: 4.05 tons submerged, 3.85 tons surfaced
Speed: 7.5 kt max, 6 kt cruising
Operating depth: 60m (180ft)
Max depth: 100m (300ft)
Range: 30 nm
Crew: 4 swimmers
Armament/payload: 1 large mine or stores container up to 820kg. 8 x 124mm mini-torpedoes.
Sensors: Optronics mast, INS (internal navigation system), autopilot, OAS (obstacle avoidance sonar), multi-function buoy.

The prototype did not meet performance and handing requirements. Modifications were made to the control surfaces, adding flow conveyors to the rear hydroplanes and additional vertical fin area.

Additionally, the deal came at a difficult time for the company. It was under the leadership of international arms dealer Carlos Cardoen who had replaced the Italian founder Ing Pucciarini. Cardeon was willing to supply arms to sanctioned countries including Iraq under Saddam Hussein, and even tried to sell the entire Cos.Mo.S company to him.

Eventually in the early 2000's the Italian Government stopped the Iraqi deal and, combined with other sour deals, the company defaulted. Cardoen was subject to an international arrest warrant but evaded capture.

The prototype CE4F was relegated to storage and is now, fifteen years later, on display at the university. Subsequent development is unclear.

Cos.Mo.S CE4F 4-man SDV
Photo from Yildiz Teknik University website

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