By DCist contributor Elliot Carter

Over the past 75 years, just about every Navy warship has spent some time, in miniature form, in a pool in Bethesda.

That would be the David Taylor Model Basin, built so that naval engineers could perfect their designs in the nautical equivalent of a wind tunnel. Testing of miniature models is a surprisingly important element in shipbuilding, and defense contractors have tested every Navy ship in this half-mile long tunnel prior to construction.

The David Taylor Model Basin is one of the largest of these testing facilities in the world. Intricately controlled waves are generated at one end by a pneumatic wavemaker, and absorbed on the other by a damper. The wavemaker can precisely simulate a range of weather conditions to assess performance on the open seas or in a hurricane force storm. A sliding platform that bridges the oblong pool moves with the models and gathers data using high speed cameras and sensors.

The engineering of this system is remarkable. According to the American Society of Mechanical Engineers: “To meet requirements for uniformity … the rails on the basin walls upon which these carriages will run had to be far straighter and more level than the most perfect railroad track. In fact, to eliminate the effect of gravity on the motion of the towing carriage, the tracks are not straight in the usual sense, but follow the curvature of the earth.” The foundation of the building was laid directly on bedrock to ensure that the rails stay perfectly aligned.

The half-mile long pool is the largest at the David Taylor Model Basin, but there are also smaller ones specialized for certain tests. Shallow water, deep water, and turning pools help testers gather important data that they could not get in the high speed basin.

The basin’s predecessor was located at the Navy Yard. The 1896 Experimental Model Basin was state of the art in its time, but by 1910 flaws in its design were apparent. The riverside foundation was settling unevenly in the ground, and the nearby Anacostia occasionally flooded the facility. The David Taylor Model Basin, named for the engineer who designed the Experimental Model Basin, replaced it in 1940.

In addition to the storied basin facilities, the models themselves are also worth marveling at. This is the domain of the Navy Ship Model Program, a niche office that includes a Curator of Models and three conservationists. They produce and conserve models of all types: from utilitarian hull prototypes to intricately detailed museum pieces that can weigh thousands of pounds.

These decorative models are on display across the country. The best collection in D.C. is at the National Museum of the US Navy, where you can find a ten-foot long model of the USS Missouri that was built over 77,000 man hours at the cost of millions of dollars. The museum is open to civilians during normal business hours Monday through Friday, and service members or contractors can get in on the weekends (10 a.m. to 5 p.m.) with their DOD CAC card.

Visiting the David Taylor Model Basin in Bethesda is also possible, but it’s a bit trickier. U.S. citizens can arrange to take a tour, which are offered on the third Thursday of the month (they recommend getting in touch at least three weeks in advance to schedule it). All visitors are prohibited from taking selfies, or any other photography for that matter.

And there are a couple of other way to get in—if you happen to be a skilled whitewater rafter or engineering student. A local Potomac racing club has been coming to the basin since the 1970s to train in the evenings and on weekends. And the basin turns into an obstacle course every year for the International Human-Powered Submarine Races, where students compete with human-powered subs.