DRASS

Updated: DG-450 and DG-350 added. Originally posted 10th June 2017.
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 - Covert Shores
Quick reference table to DRASS and historical Cos.Mo.S types. In all cases DRASS designs have been updated.

Drass SDVs and midget submarines
Flag 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:
Drass SDVs - Covert Shores
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.
Drass SDVs - Covert Shores
Drass SDVs - Covert Shores


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DG-450 Shallow-water Attack Submarine
Drass SDVs - Covert Shores
The largest type in the DRASS line up, the 450 ton DG-450 is significantly larger than any reported Cos.Mo.S designs. It can carry two 6-man SDVs and three heavyweight torpedoes making a truly multi-role platform in littoral waters.
Drass SDVs - Covert Shores

DG-450 Specification
Displacememt: 369 tons surfaced, 451 tons submerged
Length: 34.8 m
Width: 3 m hull diameter, 4.3 m with hydroplanes
Height: 7.15 m
Crew: 9 + 12 PAX
Range: 3,000 nm, 200 nm on batteries
Speed: 12 kt max, 5 kt cruising, 9 kt surfaced
Operating depth: 150 m
Armament: 3 x 533mm torpedoes standard, plus 4 x lightweight torpedoes or 8 x mines in lateral tubes as mission-specific load
Other: 2 x 6-man SDVs or 2 x 8-man inflatable boats and up to 12 Special Forces containers
Equipment: Passive Sonar, Obstacle Distance Measurement System, SWR Intercept Sonar, Radar Warning Receiver, Electronic Support Measure (OPTIONAL), TV Periscope System (2nd Periscope Optional), HF Transceiver, UHF/VHF Transceiver, Underwater Communication System, Sound Powered Telephone, Intercom Network, Inertial Navigation System, Echo Sounder with Sound Velocity, Doppler Velocity Log

Drass SDVs - Covert Shores




DG-350 Shallow-water Attack Submarine
Drass SDVs - Covert Shores

Drass SDVs - Covert Shores

DG-350 Specification
Displacememt: 291 tons surfaced, 352 tons submerged
Length: 34.8 m
Width: 3 m hull diameter, 3.5 m with hydroplanes
Height: 7.15 m
Crew: 9 + 12 PAX
Range: 2,500 nm, 200 nm on batteries
Speed: 12 kt max, 5 kt cruising, 9 kt surfaced
Operating depth: 150 m
Armament: 3 x 533mm torpedoes standard, plus 2 x lightweight torpedoes or 8 x mines in lateral tubes as mission-specific load
Other: 2 x 4-man SDVs or 2 x 8-man inflatable boats and up to 12 Special Forces containers
Equipment: Passive Sonar, Obstacle Distance Measurement System, SWR Intercept Sonar, Radar Warning Receiver, Electronic Support Measure (OPTIONAL), TV Periscope System (2nd Periscope Optional), HF Transceiver, UHF/VHF Transceiver, Underwater Communication System, Sound Powered Telephone, Intercom Network, Inertial Navigation System, Echo Sounder with Sound Velocity, Doppler Velocity Log

Drass SDVs - Covert Shores




DG-160 Shallow-water Attack Submarine
Drass SDVs - Covert Shores
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.
Drass SDVs - Covert Shores
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.

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 lateral 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

Drass SDVs - Covert Shores




Drass SDVs - Covert Shores
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.

Drass SDVs - Covert Shores
Drass SDVs - Covert Shores
Drass SDVs - Covert Shores

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

Drass SDVs - Covert Shores




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.
Drass SDVs - Covert Shores
Drass SDVs - Covert Shores

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

Drass SDVs - Covert Shores




DG2 EN 2-man SDV
Drass SDVs - Covert Shores
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: Cos.Mo.S CE2F chariot

Drass SDVs - Covert Shores
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

Drass SDVs - Covert Shores


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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.
Drass SDVs - Covert Shores

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.
Drass SDVs - Covert Shores

Main article: Cos.Mo.S CE4F

Drass SDVs - Covert Shores
Drass SDVs - Covert Shores

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.
Drass SDVs - Covert Shores

Drass SDVs - Covert Shores
Drass SDVs - Covert Shores
Drass SDVs - Covert Shores
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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This Covert Shores Recognition Guide Covers over 80 classes of submarines including all types currently in service with World Navies.
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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.
Drass SDVs - Covert Shores
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.




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Flag Cos.Mo.S Nessie Fast SDV submersible boat

Flag Cos.Mo.S CE4F 4-man SDV

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Flag COMSUBIN's submersible boat

Flag Chinese MS200 midget submarine
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