The US Navy put stealth destroyer Zumwalt to the test by sailing it into a very rough storm with waves as high as 20 feet

• The Navy destroyer USS Zumwalt purposefully sailed into "very rough" seas last fall for a test.
• The ship sailed through storms off the coast of California and Alaska with waves up to 20 feet high.
• The Zumwalt successfully passed the Rough-Water Trials.

The US Navy put the stealth destroyer USS Zumwalt to the test by sailing it straight into a storm with waves as high as 20 feet, Naval Sea Systems Command announced recently.

Navy engineers tested the destroyer in storms off the coast of California and Alaska last fall as part of the second phase of the Rough-Water Trials. The ship held up in Sea State 6 conditions with waves as high as 20 feet.

The World Meteorological Organization Sea State scale runs from 0 to 9. Sea State 6 is considered "very rough." The conditions are atypical and punishing for the ship and its crew. Sailors are unlikely to face them more than a few times in their careers.

The first phase of the trials, part of the Performance and Special Trials program, was conducted in 2019. The Zumwalt sailed through Sea States 3, 4, and 5, mild to rough conditions with waves ranging in height from just under two feet to 13 feet.

That testing was preceded by Calm-Water Trials not to far from DDG-1000's home port in San Diego, California. With the latest tests in rougher waters, during which the warship did not experience any unsafe motion outside acceptable limits, the PS&T program is complete.

Before the Zumwalt was first put to sea, there were questions about whether or not the ship's tumblehome hull could provide the desired stability. There were even concerns that the ship might roll over in certain conditions.

The captain of the Zumwalt told Defense News, which first reported the latest trials, last January about a stormy situation near Alaska the year prior that involved Sea State 6 conditions.

Capt. Andrew Carlson said that the ship "really handles well," telling the outlet that "I'd rather be on that ship than any other ship I've been on."

"You definitely have to get used to the roll, which is very short compared to other ships," he said. "For those of us who have been on cruisers, especially up top, you kind of lean over 15 degrees and you wonder if you are going to come back. We didn't experience any of that."

Naval Sea Systems Command said that last year's Rough-Water Trials "confirmed prior characterization of the seakeeping behavior of DDG 1000 in severe wave environments."

The Navy commissioned the Zumwalt, the first of a new-class of destroyers, in 2016, but the warship was not delivered to the service with a working combat system until April of last year.

DDG-1000 fired its 30 mm Mk 46 MOD 2 Gun Weapon System for the first time last May and first launched a SM-2 missile from its Mk 57 Vertical Launching System last October.

Among problems like cost overruns and major delays, a big problem with the Zumwalt was the two 155 mm guns of the Advanced Gun System.

When the Navy reduced its order for Zumwalt-class ships from roughly thirty ships to just three, the cost of the rounds for the guns shot up. A single round of the Long-Range Land Attack Projectile was going to cost almost $1 million.

The unacceptable price of the ammunition was just one of the problems with the guns that forced the Navy to reevaluate the combat system and change the ship's mission from a naval fire support role to one focused on anti-ship combat.

The three ships of the class are the Zumwalt, Michael Monsoor, and Lyndon B. Johnson. Only the lead ship has been delivered to the Navy.