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Drass SDVs and midget submarines

Discussion in 'Naval Warfare' started by Zarvan, Nov 14, 2017 at 12:11 PM.

  1. Zarvan

    Zarvan ELITE MEMBER

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    DRASS
    Mon 13 November 2017By H I Sutton


    Updated. Originally posted 10th June 2017.
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    This article relies heavily on information from unnamed individuals. Sincere thanks to everybody who has helped.Information and corrections welcome. Contact the author HERE

    Drass SDVs and midget submarines
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    [​IMG] The secrecy surrounding Italian Swimmer Delivery Vehicle (SDV) manufacture is legendary. Drass are an established name in the defense industry supplying hyperbaric chambers for diver decompression. They also offer a range of SDVs and midget submarines based directly on the previous Cos.Mo.S designs. Their connection to Cos.Mo.S has been known in relevant circles but it is only very recently that they went public with their new-build SDV offering, and you still may not find any information on their website (at time of writing). This article introduces the SDV types and cross-references them to the Cos.Mo.S design heritage.

    Before involvement with the Cos.Mo.S designs, Drass (formerly Roberto Galeazzi) had previously designed SDVs:
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    From Drass website

    Based in La Spezia, conveniently near to the Italian naval Special Forces (COMSUBIN), Drass were close neighbors of Cos.Mo.S during the time that the latter was a major midget submarine and SDV exporter. So it is not entirely Surprising that Drass have taken over the Cos.Mo.S designs after they went out of business (see notes HERE). Although the fundamental designs are established classics from Cos.Mo.S, Drass has incorporated up to date lithium-ion battery technology, a new control and navigation module and the latest generation of sensors.
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    DG-160 Shallow-water Attack Submarine
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    The largest DRASS midget-submarine, the 140 ton DG-160 is reminiscent of the unbuilt Cos.Mo.S X-201 SWATS submarine concept but with a more conventional ‘+’ tail section based on the MG-120 design.
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    left: photo of Cos.Mo.S MG-120 bow with twin torpedo tubes and sonar dome on top, right: CG of DG-160 with two DRASS DG2 SDVs on deck.

    CLICK for HIGH-RESOLUTION image.
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    DG-160 Specification
    Displacememt: 141 tons surfaced, 169 tons submerged
    Length: 32.24 m
    Width: 2.5 m hull diameter, 4.12 m with hydroplanes
    Height: 6.45 m
    Crew: 7 + 8 PAX
    Range: 2,000 nm, 160 nm on batteries
    Speed: 10 kt max, 5 kt cruising, 8.5 kt surfaced
    Operating depth: TBC
    Armament: 2 x 533mm torpedoes standard, plus 2 x 533mm torpedoes or 6 x mines in laterial tubes as mission-specific load
    Other: 2 x SDVs or up to 6 x inflatable boats
    Equipment: Passive sonar, active sonar, SWR Intercept Sonar, Radar Warning Receiver, TV periscope, Underwater Communications, Ring-Laster gyrocompass, echosounder, doppler velocity log, Electromagnetic log

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    DG-120 Shallow-water Attack Submarine
    The DG-120 sacrifices Special Forces payload for a larger complement of wire-guided 400mm torpedoes with 11 nautical miles range. Only two commandos can be carried in addition to the seven-person crew.

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    DG-120 Specification
    Displacememt: 115 tons surfaced, 130 tons submerged
    Length: 28.2 m
    Width: 2.3 m hull diameter, 3.92 m with hydroplanes
    Height: 6.4 m
    Crew: 7 + 2 PAX
    Range: 1,800 nm, 120 nm on batteries
    Speed: 9 kt max, 4 kt cruising, 7.5 kt surfaced
    Operating depth: TBC
    Armament: 6 x 400mm torpedoes, 6 mines.
    Other: 1 x inflatable boat
    Equipment: Passive sonar, active sonar, SWR Intercept Sonar, Radar Warning Receiver, TV periscope, Underwater Communications, Ring-Laster gyrocompass, echosounder, doppler velocity log

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    DG-85 Shallow-water Attack Submarine
    The smallest of the DRASS midget submarine designs, the DG-85 is intended for a) attacks on ships moored in harbor or harbor installation using the 6 mines which are carried externally, b) patrol of coastal areas as deterrent against enemy ships approaching own coastal targets using 400mm wire-guided torpedoes, c) Intelligence gathering using acoustic, electronic and communication (SIGNIT) sensors, and d) deployment of mines in very shallow waters / harbor mouths.
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  2. Zarvan

    Zarvan ELITE MEMBER

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    DG-85 Specification
    Displacememt: 81 tons surfaced, 94 tons submerged
    Length: 21.06 m
    Width: 2.2 m hull diameter, 3.82 m with hydroplanes
    Height: 5.75 m
    Crew: 6 + 1 PAX
    Range: 1,500 nm, 100 nm on batteries
    Speed: 7.5 kt max, 4 kt cruising, 6 kt surfaced
    Operating depth: TBC
    Armament: 2 x 400mm torpedoes, 6 mines.
    Equipment: Passive sonar, active sonar, SWR Intercept Sonar, Radar Warning Receiver, TV periscope, Underwater Communications, Ring-Laster gyrocompass, echosounder, doppler velocity log

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    DG2 EN 2-man SDV
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    The DG2 EN design is a direct evolution of the Cos.Mo.S CE2F X100 design and is intended purely as an offensive system to carry two combat swimmers From a host submarine (or vessel) to within range of their enemy ships in port or at anchor.

    Main article: [​IMG]Cos.Mo.S CE2F chariot

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    The hull is still recognizable as the CE2F but is rearranged with the crew air bottles moved inside the hull (not below the hull) and the belly payload removed. This is similar to the Cos.Mo.S CE3F design which was produced for South Korea. And like the CE3F, the canopy structure has lost its ‘head and shoulders’ cross-section. The payload is carried behind the crew in a locker on the back of the boat.

    DG2 EN Specification
    Length: 7.56 m
    Width: 0.8 m without hydroplanes
    Height: 1.3 m
    Weight (dry): 2.4 tons
    Crew: 2
    Range: 80 nm
    Speed: 4.8 kt max, 3.5 kt cruising
    Operating depth: TBC
    Host submarine transit depth: 100m
    Payload: Special Forces stores or 6 limpet mines carried in locker on back of craft

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    DS4 4-man SDV
    The DS4 is a minimal evolution of the Cos.Mo.S CE4F project for the Turkish Navy's SAT (Su Altı Taarruz) in the late-1990s to early-2000s.
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    The design does not have some of the post-delivery alterations which were added to the CE4F (see below) but does have the additional stabilizers running along the lower hull.
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    Main article: [​IMG] Cos.Mo.S CE4F




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    DS4 Specification
    Length: 8.6 m
    Width: 1.44 m hull diameter, 2.0 m max with
    Height: TBC
    Weight (dry): 3.49 tons
    Crew: 2 + 2 PAX
    Range: 110 nm
    Speed: 7.5 kt max, 5 kt cruising
    Operating depth: 50 m
    Host submarine transit depth: 100m
    Payload: Two sealed containers for Special Forces stores or limpet mines. Provision for 8 mini-torpedoes.
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    These photos, used by Drass in reference to the DS4, are of the Cos.Mo.S CE4F before delivery to Turkey


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    DS6 6-man SDV
    The DS6 is Drass’ answer to the 6-man SDV market which is dominated by US, French and British designs. This allows a team of four Special Forces operators to be transported for a cross-beach mission.
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    Analogous to the unbuilt Cos.Mo.S CE6F design, the DS6 is a lengthened DS4 with an additional row of diver’s sitting in the rear compartment. The air supply is increased but otherwise most systems remain the same, leading to a slight compromise in performance to accommodate the extra passengers.

    DS6 Specification
    Length: 9.1 m
    Width: 1.44 m hull diameter, 2.16 m max with hydroplanes
    Height: TBC
    Weight (dry): 3.66 tons
    Crew: 2 + 4 PAX
    Range: 70 nm
    Speed: 7 kt max, 5 kt cruising
    Operating depth: 50 m
    Host submarine transit depth: 100m
    Payload: Two sealed containers for Special Forces stores or limpet mines. Provision for 8 mini-torpedoes.



    http://www.hisutton.com/DRASS.html
     
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  3. Khafee

    Khafee SENIOR MEMBER

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    @Zarvan A very good thread! Thank You :tup:
     
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  4. Maxpane

    Maxpane FULL MEMBER

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    hm