Developing the technology required to keep the military of the US and our allies on the cutting edge isn't easy. It requires billions of dollars and tens of thousands of people, all working to push the equipment available forward. A lot of this work isn't particularly glamorous or exciting, but occasionally, it requires some truly incredible facilities.
My favorite of these is the David Taylor Model Basin in Carderock, Maryland. This is "Where the Fleet Begins", the place where the Navy does the basic research that ultimately feeds into operational warships. Even today, computers are not capable of the accuracy needed when simulating the flow of water around a ship. To make sure that our next vessels will be as fast and as seaworthy as they need to be, physical models must be tested. And the best way to do that is to create a giant tank and tow a model through it. Of course, it's not nearly as easy as it sounds, and DTMB is one of the world's premier facilities for such research.
The heart of DTMB is the three towing tanks: the deepwater basin, the shallow-water basin, and the high-speed basin. The deepwater basin is 2,775' long, 51' wide, and 22' deep, and is fitted with a wavemaker capable of simulating heavy seas, which can have a significant impact on ship performance. The towing carriage over the basin can travel at up to 20 kts, dragging a model up to 32' long and weighing 5 tons and precisely measuring the forces it takes to do so. The shallow-water basin is at one end of the deepwater basin, and they can be connected if needed for certain tests. It is 303' long, 10' deep, and ends in a 180° J-turn used for testing turning performance. A model will be towed by the carriage up to speed with its rudder fixed in a turn, then released. When the basin was built in the 1940s, tracking was done by fitting the model with lights and dousing all others in the building, then filming the turn. Today, the turning basin is rarely used, as other facilities are better for this type of analysis.
The high-speed basin runs parallel to the two other basins, a full 2,968'. It's only 21' wide, and the depth varies from 10' to 16', but one of the carriages can tow models of high-speed craft, hydrofoils and seaplanes at up to 60 kts. All of the basins are fitted for photographic studies as well as towing force measurements, and were specially leveled to within .005", following the curvature of the Earth. The models used in them are built by DTMB's own model shop, and for decades were hand-crafted to the lines given by naval architects.
Backing up the towing tanks is the Maneuvering and Seakeeping Basin (MASK). This is a one-of-a-kind facility designed to replicate virtually any sea conditions using 216 independent electromechanical wave generators. Models can be towed through them at any angle to measure the forces involved, or free-running models up to 30' long can be used in the 360' x 240' tank. The same building also has a rotating-arm system designed to measure the performance of ships while turning. The basin is 260' across and 21' deep, with an arm on the stand in the center. Models towed from it can reach speeds up to 50 kts in a single revolution, and give unique information on stability, control and maneuverability.
Nor are model basins the only interesting and unique capabilities at DTMB. Despite the old-school methods used to get much of this data, the facility has been on the cutting edge of computer modeling of ship motion and other effects since 1953, when it received its first digital computer, a UNIVAC I. It has facilities for acoustics research, including an anechoic wind tunnel, a circulating water channel that allows hydrodynamic analysis on a static model, and a number of pressure tanks that are used to validate submarine equipment and even scale models of submarine hulls. Several water tunnels are used to study propeller designs, and labs specialize in ship materials and structures. The largest underwater explosives test pond in the country is at DTMB, and it's fully equipped for underwater photography to help develop structures that can resist underwater explosions.
For more information on DTMB, check out this article on the towing tanks from a 1943 issue of Popular Science and the book Where The Fleet Begins, a history of the facility through 1998. I was privileged to be able to visit NSWC Carderock in October 2021, and have written up my experience here.