Clever design- CSS-1 collapsible SDV

Flag The concept of folding canoes is common in military circles, but conventional thinking has it that Swimmer Delivery Vehicles (SDVs) are too large. Their bulk requires winches or cranes and dedicated trailers to transport them. The smallest SDVs, termed Diver Propulsion Vehicles (DPVs) can be carried short distances by hand but have to sacrifice the streamlined fuselage altogether, leaving the swimmer exposed to the oncoming water. This compactness comes at a price because it reduces speed and thus range. Prolific Submarine designer Carsten Standfuss, best known for the EURONAUT wreck diving submarine, came up with a clever way around this problem. What if SDVs were collapsible also?

Carsten, who has an extensive knowledge and archive of SDV and small submarine developments and contributed to the Covert Shores book, recently found these plans and photos of the project. Although technically a civilian/hobby project, I feel that the concept is ingenious. It is so obvious when someone else has thought of it! I love it so I am sharing.
Clever design- CSS-1 collapsible SDV

The tandem layout was similar to the successful HAVAS and Cos.Mo.S military wet subs.
Clever design- CSS-1 collapsible SDV
The CSS-1 (also CSSX-1) was designed to have the fuselage constructed from four essentially identical fiberglass sections, which bolted together to form a two-man chariot style wet sub. When disassembled, the bulky fuselage sections stacked together like plates.

Initially the four sections (forward top and bottom, aft top and bottom) are made using the same mold. The forward top part then has a cutout for the forward driver, the stern top part has a cutout for the aft driver. The stern bottom part is uncut like the bow bottom part.
Clever design- CSS-1 collapsible SDV

The nose contains a lamp or echosounder in the bow, and the stern has a similar hole for the thruster motor with a Kort nozzle (a ducted propeller). The four rudders are shown are in the standard ‘+’ configuration but the decision was made for the same rudders in an ‘x’ configuration.

In general it just four different parts:
- 4x GRP shell
- 4x rudder/hydroplanes aft
- 2 x forward hydroplanes
- 2x watershields

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The horizontal connection between the hul sections was sealed by a black Bumper rubber gummi about 5-6 cm high and all around, backed up by some security screws. The vertical connection by a metal frame behind the GRP and sunken screws about all 6 - 8 cm. All tanks for ballast water and batteries are screwed or clamped for easy removal and maintenance.

The design progressed to the construction of molds for the fiberglass work but halted as other projects took precedence. What could have been….
Clever design- CSS-1 collapsible SDV
Clever design- CSS-1 collapsible SDV
The orange/gold craft standing vertically on the bench in the background is a modified Aquazepp Diver Propulsion Device (DPV).

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