The Navy's inner ocean, the mask, tests ships and other ocean technologies

The Navy’s inner ocean, the mask, tests ships and other ocean technologies

  • The Naval Maneuvering and Sea Sailing Basin, or MASK, is one of the largest inland ocean testing facilities in the world.
  • Ships, submarines and other naval vessels are tested here from design to completion.
  • The massive wave pool can simulate almost any real ocean condition.

The newest US Navy warship, the USS ZumwaltIt will be a leap forward in the latest naval defense technologies. It will have an electric propulsion system, a “wave piercing” pointed bow, a stealth design, as well as advanced weapons, to me all handsMarine Journal. But before that ship can hit the waves, its safety and naval capabilities must be tested at the Navy’s massive Inland Ocean Facility.

One of the first steps to building a new military ship of any kind is to thoroughly examine it for strengths and weaknesses, in the test waters of the Navy’s Maneuvering Dock and Seakeeping Dock, or mask. The 240-foot-wide, 360-foot-long pool holds more than 12 million gallons, and it tests military and non-military ships for seaworthiness. These include ships, submarines, and autonomous vehicles that are used to it Research in ocean conditions.

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The mask can simulate virtually any marine condition around the world’s oceans. “We can test small-scale models of Navy ships in every single environment that you will encounter as a full-size ship,” Steve Oymet, deputy technical director of the Naval Surface Warfare Center in Carderock, Maryland, where MASK is located, tells popular mechanics. “We can fully understand what that big ship is going to do. And these facilities allow us to do that.”

The pool itself is 20 feet deep with dark blue water, with a 35-foot moat. Along the sides, a train of long, thin oars protrudes above the surface of the water and sometimes moves in a snake-like manner. They can create any kind of wave a ship might encounter in the ocean, and drop ship models ranging in size from 10 to 30 feet. Electric motors and a timing belt drive the motion of the wave machine’s paddles, as they oscillate in and out of the pool wall.

In 2013, the facility replaced its 21 pneumatic domes, which were slower and less responsive, with 216 individually controlled paddles in the pool’s confines. The long, slender paddles are about six feet long and three feet wide, and can raise waves from a variety of angles along the pool, mimicking long and short irregular waves. The waves can propagate in any direction as desired. Swells can cover the pool, or they can be localized in just one section. Oars can also recreate eddies, which may happen at sea when fast-flowing tides enter narrow straits. The shallow “beach” area can test the conditions that occur when waves bounce off the coast.

Navy Inner Ocean Test Mask

The Wave Energy Prize competition is in its final phase of testing at the Naval Surface Warfare Center, Carderock Division, hosted by the US Department of Energy in 2016.

Monica McCoy / Public Domain

Perhaps the most powerful part of the upgraded system is the precise computer control. Testers can design a specific sea state and program a computer to create it. Operators can call up a virtual 3D model of the types of waves they want, even before executing a specific wavemaker program.

Repetition is key to accurate testing, says Miguel Quintero, who runs the facility. He and his team design experiments and build models and tools for testing. Because the system allows the same test to be run multiple times under the exact same conditions, testers can collect more data and be confident in the results.

The thing is, when those waves finally move, the water that bounces back creates hydrostatic pressure on the wave-making paddles. Sensors detect this pressure, and a computer algorithm determines how much power the paddles need. Then the paddles can continue to move at the correct speed and frequency to precisely generate a specific type of wave.

The wave pool includes two transducers that track what is happening in the tank at any given moment while the wave is in action. This computer feedback means the system can precisely control the waves, stopping them completely when desired. “There’s a controller that says, ‘We’re making this wave and it’s going to travel that fast,’ and this racket knows what shape to expect, at what time. So you either push a little or pull back a little to help maintain shape,” Quintero says. popular mechanics.

Waves can be up to three feet high for one large wave, or up to a foot high for a pool full of waves. But the tides in the wave pool don’t actually expand in an ideal proportion to the actual waves of the ocean. “These two processes are the same, but on different levels, they interact differently,” Quintero says. The length can be scaled straight up or down, so at a hypothetical 10:1 scale, a 40-foot wave in the ocean would be equivalent to, say, a four-foot wave in an artificial environment.

Testers are more interested in two other wave components: amplitude (the height of the wave) and frequency (the number of times a new wave arrives in a specified period of time). If the test required examining the effects of real three-foot-high ocean waves that hit a ship every 10 seconds, they couldn’t just divide those numbers down to get a simple ratio. The periodicity of the wave – the number of times it hits the bow of a ship, for example – requires calculating the square root of the time period. “So the actual smaller wave will look a little different than the full size, because the amplitude and period don’t scale the same,” Quintero says.

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Ship Power Challenge

Ship design testing begins long before a new type of ship or ship modification is built. Once shipbuilders have a new requirement, say the ability to go at a certain speed or carry a larger amount of cargo, the MASK test takes those features into microcosm and puts them against all the sea conditions a ship might encounter. The tests will closely examine how different parts of the ship perform under calm and adverse conditions, including the propeller, artillery, and other parts of the ship that struggle to resist drag or water, especially in volatile conditions. Testers can go back to the shipbuilders and tell them what to expect, based on how they perform at MASK.

“Our job is to reduce the risk, to make sure that if we’re going to spend that much money building a ship, it’s going to do whatever we want it to do. And we’re going to get a full understanding of what that ship is going to do in all of those environments… to help the designers focus on the actual design that’s going to be The end product, says Ouimette.

The next stage is to build a full-scale model. MASK puts the tools into the full version to collect data, then compares them to how the younger and older model works. This also helps predict which design features are safe to keep and which ones should be modified or eliminated. Ultimately, builders can proceed with the modification or new vessel with confidence that safety and performance will not be affected, says Ouimette. “It’s good to know that the work we’re doing will help the people in the fleet.”

You can’t just enter the facility for a casual visit to watch the model ships swing back and forth. But you can watch the paddles in action and get an idea of ​​the sheer size of the pool MASK YouTube page.

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