Naval Experimental Testbed SV-04

The Central Committee has focused the development of two main categories of combat vessels: heavy ironclads as the main line of battle and fast moving Shchuka Boats for coastal patrols. Despite this they have seen the potential utility in a third specialized type of military vessel which could prove invaluable, an airtight craft able to conceal itself by submerging itself underwater. Experiments in this field began in 28 IA, though developments in said field have been accelerated since the onset of the escort war under the Ministry of Industry and Technology's SV (Submersible Vehicle) project.

SV-01 was an experiment in regards to life support capacity completed in 29 and was little more than a two meter long steel drum with compressed air tanks weights into which a young pig was enclosed, submerged under ten meters of water for periods of eight to twelve hours and then brought up by winch. As the pig survived the six tests this lead to the construction of SV-02 in 31 IA, an enlarged version with a view port, electric light and a seat for the naval volunteer to test it's effects on humans, using fifteen volunteers. Again this system proved to be effective. SV-03 was a more extensive design completed in 33 IA. While broadly similar to SV-03 it involved a set of ballast tanks. There were several problems with this design which meant that it had to go through several rebuilds before it was satisfactory in terms of both functionality and reliability. The onset of the escort was disrupted further development in the project but despite that two weeks after the Battle of Daagsgrad SV-04 was ready for service. Infrastructure's first fully functional manned submarine.

Measuring 13.5 meters from stem to stern and weighing 20.6 tonnes, SV-04 (nicknamed by her crew the Osetr) had a crew of eight specially trained sailors. Her construction incorporates a large number of specialized systems. Her most notable feature is that she can spend up to twenty four hours fully submerged at depths of up to 10 meters.  She is powered by a single 40kw electrical motor powered by a set of lead acid power cells (which could be swapped out for Fabricated power cells which have a energy density several orders of magnitude greater), allowing her to achieve a speed of up to 12km/h on the surface and 5km/h submerged. After a couple of 'pig trials' to test it's air supply she was set on her maiden voyage in escort with the Ironclad Revenge completing a 15 km long circuit including a submergence test. A longer sea test followed a few weeks latter, followed by several more tests.

While a few mechanical issues cropped up the SV-04 was in general a success as a test bed for naval technology. Even so the Central Committee in February 37 IA gave the official statement that while the progress made in this field is considerable, viable military submarines are still a long way off. Despite it's comparatively small size and the unexpected boon of rubber components the SV-04 was quite costly in terms of both manpower and machine production. It is also slow, low range (officially rated at 800km surface) and is unarmed. Research will continue but in the estimations of the Central Committee it will be a decade before viable armed submarines can be put into production.