DDG 1000 Zumwalt Goes to Sea

By Chuck Oldham (Editor) - December 8, 2015

Zumwalt at sea for the first time. DDG 1000's tumblehome hull, wave-piercing bow, large deckhouse incorporating the ship's radar, sensors, and stacks, and the enclosed turrets for its 155mm guns are all features maximized for stealth at sea (see story below). U.S. Navy photo courtesy of General Dynamics Bath Iron Works

The future USS Zumwalt (DDG 1000) underway for the first time conducting at-sea tests and trials on the Kennebec River. The multimission ship will provide independent forward presence and deterrence, support special operations forces, and operate as an integral part of joint and combined expeditionary forces. U.S. Navy photo

Onlookers gather to watch and take photos as the future USS Zumwalt (DDG 1000) departs for sea tests and trials. U.S. Navy photo courtesy of General Dynamics Bath Iron Works

The future USS Zumwalt (DDG 1000) underway on the Kennebec River. The two turrets for the 155 mm gun turrets, wave piercing bow, and single large deckhouse are very evident in this photo. U.S. Navy photo courtesy of General Dynamics Bath Iron Works

Zumwalt at sea seen from the bow shows just how radical her design is. The ship's vertical launch tubes for her missiles are arrayed down the sides of the ship. U.S. Navy photo courtesy of General Dynamics Bath Iron Works

The newest class of U.S. Navy destroyer, named for CNO Adm. Elmo Zumwalt, left Bath Iron Works shipyard in Maine for her first sea trials Dec. 7. Zumwalt (DDG 1000), with the tonnage and size of a cruiser, is first of an abbreviated class of three. Originally meant to be a class of 32, rising costs caused the remainder of the ships to be cancelled, and the class are now envisioned as being more like floating testbeds for a range of technologies.

Their two 155mm (6.1-inch) Advanced Gun System naval rifles are planned to be capable of launching guided, rocket-assisted rounds up to 83 nautical miles, and are water-cooled to maintain a rate of fire of 10 rounds per minute per gun. However, the Navy plans to test its first electronic railgun on a ship of the class as well.

The ships were always meant to be optimized for land attack, but have air defense capabilities as well through their Peripheral Vertical Launch Systems. The system incorporates 80 vertical launch tubes just inside of the skin of the ship, with a thicker inner skin protecting the ship’s vitals in case the missiles are struck by enemy fire and explode. The principal is similar to blow-out panels in armored vehicles.

Because of the scale and power of their integrated electrical systems, they are the best candidates to carry the Navy’s first practical railguns and powerful free electron lasers to sea. The class employs turbo-electric power, where four jet turbines power the ship’s electrical grid as well as the electric motors for propulsion. While other ships use podded electric motors, however, the U.S. Navy stayed with traditional internal electric motors driving propeller shafts piercing the hull. The electric motors contribute to the ship’s acoustic signature being very low.

The DDG 1000-class destroyers displace more than 15,761 tons, and are 610 feet long at the waterline, the first ships in decades to be longer in that dimension than overall due to their tumblehome hulls and wave-piercing bows. The tumblehome architecture is one aspect of their stealth shaping, and a controversial one, with some questioning their stability.

Along with the hull, the deckhouse and gun turrets (with fully enclosed barrels until firing) are composed entirely of sloped and angled planes to deflect radar waves, with minimal openings and projections for ship’s boats, anchors, and antennae to reflect radar waves. The antennas of the ship’s SPY-3 radar are integral parts of the ship’s deckhouse, and set flush with its skin. Initially the ship was intended to have a dual band radar, but this was abandoned. The ship’s mack (mast and stack) also employs passive cool air induction to lower the infrared signature. The upshot of these design aspects is said to be a radar signature comparable to a small fishing boat.

Up until now very few photos of the Zumwalt have been released, and those that have emphasize her lines from one or two angles. Seen in these photos, the ship looks powerful and purposeful. But any nod to beauty and grace has been discarded in the pursuit of stealth shaping, the likes of which likewise made the Air Force’s F-117 very efficient in terms of low observability, but hardly a thing of beauty.