Washington State University 'semi-sub’ shows military potential of sailing at waterline

A team of researchers from Washington State University (WSU) has developed a semi-submersible unmanned vehicle that eventually could change the way people travel in water.

According to a WSU Insider report, the prototype is 1 1/2 feet long and constructed from 3D printed and off-the-shelf parts and tested for seaworthiness in water, demonstrating its low drag and low profile. 

“A semi-submersible vehicle is relatively inexpensive to build, difficult to detect, and it can go across oceans,” said Konstantin Matveev, a WSU engineering professor leading this work, in the report.

According to the report, the research team published the results of its efforts in the journal Unmanned Systems. The study also noted that, while semi-subs have been used for nefarious reasons for years, the WSU team hopes to show how they can be used effectively by the military.

“It’s not so susceptible to waves in comparison to surface ships since most of the body is underwater, so there are some economic advantages as well,” Matveev said.  

The report noted that the semi-sub moves in the water mostly at the waterline and does not require the same strength of materials required for a submarine, which needs to be able to stand up to pressures that come from being underwater for extended periods. 

The report also noted that by being small, with a smaller footprint to contact with the air, the semi-sub can more easily receive and transmit data and can be programmed to react in specific ways, covering a specified path or approaching or fleeing certain objects in the water, all while traveling about 3.4 mph during rests. 

The researchers added in the WSU report that they rigged the semi-sub with sonar and used the technology to make a map of the bottom of a reservoir, located near the WSU campus in Pullman, Washington, to test its capabilities of data transmission and collection. 

While measuring just 17.7 inches long and 3.9 inches in diameter, Matveev noted that larger versions of the semi-sub could be built to carry cargo. He also noted in the report that his lab is perfecting the shape of the semi-sub prototypes to fit other purposes. 

According to the report, Matveev is working with the U.S. Naval Academy in Annapolis, Maryland, to hone the operational capabilities of the sub and compare data with results from other experiments.  

Ultimately, this technology could change the future of water transportation, with semi-subs proving economic and environmental benefits over ships, according to the report. The study concluded that the crafts also could be used to refuel shops or stations at sea and eventually could be used to transport goods and materials at a cheaper cost than container ships.