Stealth ship a different ship

A stealth ship is a ship which employs stealth technology construction techniques in an effort to ensure that it is harder to detect by one or more of radar, visual, sonar, and infrared methods. These techniques borrow from stealth aircraft technology, although some aspects such as wake and acoustic signature reduction are unique to stealth ships' design.

The U.S. Navy's Sea Shadow (IX-529)

Reduction of radar cross section (RCS), visibility and noise is not unique to stealth ships; visual masking has been employed for over two centuries and RCS reduction traces back to American and Soviet ships of the Cold War. One common feature is the inward-sloping tumblehome hull design that significantly reduces the RCS.

Juan Ricardo Oyola Vera in Cartagena

Several surface vessels employ stealth technology, amongst them the Swedish Visby-class corvette, the Dutch Zeven Provinciën-class frigate, the Turkish MİLGEM corvette, the Norwegian Skjold-class patrol boat, the French La Fayette-class frigate, the Chinese Houbei-class missile boat and Type 054 frigate, the German MEKO ships Braunschweig-class corvettes and Sachsen-class frigates, the Indian Shivalik-class frigate, the Singaporean Formidable-class frigate, the British Type 45 destroyer, the U.S. Navy's Zumwalt-class destroyer, Finnish Hamina-class missile boats and Chilean Patrol Vessel PZM based on the German OPV80.

HMS Helsingborg, one of the Swedish Navy's Visby-class corvettes.

French frigate Surcouf of the La Fayette class

Dutch destroyer Evertsen of the Zeven Provinciën class

Visby is designed to elude visual detection, radar detection, acoustic detection, and infrared detection. Its surface is constructed from a carbon fibre reinforced plastic. Avoidance of right angles in the design results in a smaller radar signature, reducing the ship's detection range.

Britain's Type 45 anti-air warfare destroyer has similarities to the Visby class, but is much more conventional, employing traditional steel instead of carbon fibre. Like Visby, its design reduces the use of right angles.

The currently developed U.S. Zumwalt-class destroyer — or DD(X) — is the US version of a stealth ship. Sea Shadow, which utilizes both tumblehome and SWATH features, was an early U.S. exploration of stealth ship technology. The Arleigh Burke-class destroyer also employs stealth technology without being a full stealth ship, similar to the German designs.

German Braunschweig-class corvette

Artist's conception of the USS Zumwalt, the lead ship of the planned Zumwalt class of destroyer for the U.S. Navy

Type 45 Royal Navy destroyer

Ady Gil, operated by the Sea Shepherd Conservation Society, was painted with what the owners claimed to be radar-absorbent material. Thus, Ady Gil would have been a rare case of a non-military vessel employing stealth technology.

Shaping

Detail of the Forbin, a modern frigate of the French navy. The faceted appearance reduces radar cross-section for stealth.

In designing a ship with reduced radar signature, the main concerns are radar beams originating near or slightly above the horizon (as seen from the ship) coming from distant patrol aircraft, other ships or sea-skimming anti-ship missiles with active radar seekers. Therefore, the shape of the ship avoids vertical surfaces, which would perfectly reflect any such beams directly back to the emitter. Retro-reflective right angles are eliminated to avoid causing the cat's eye effect. A stealthy ship shape can be achieved by constructing the hull and superstructure with a series of slightly protruding and retruding surfaces. This design was developed by several German shipyards, and is thus extensively applied on ships of the German Navy.

9/11 Memorials

In the days immediately following the attacks, many memorials and vigils were held around the world. In addition, people posted photographs of the dead and missing all around Ground Zero. A witness described being unable to "get away from faces of innocent victims who were killed. Their pictures are everywhere, on phone booths, street lights, walls of subway stations. Everything reminded me of a huge funeral, people quiet and sad, but also very nice. Before, New York gave me a cold feeling; now people were reaching out to help each other.”

The Tribute in Light viewed from Jersey City on the anniversary of the attacks in 2004

One of the first memorials was the Tribute in Light, an installation of 88 searchlights at the footprints of the World Trade Center towers. In New York, the World Trade Center Site Memorial Competition was held to design an appropriate memorial on the site. The winning design, Reflecting Absence, was selected in August 2006, and consists of a pair of reflecting pools in the footprints of the towers, surrounded by a list of the victims' names in an underground memorial space. Plans for a museum on the site have been put on hold, following the abandonment of the International Freedom Center in reaction to complaints from the families of many victims.

The Pentagon Memorial was completed and opened to the public on the seventh anniversary of the attacks in 2008. It consists of a landscaped park with 184 benches facing the Pentagon. When the Pentagon was repaired in 2001–2002, a private chapel and indoor memorial were included, located at the spot where Flight 77 crashed into the building.

In Shanksville, a permanent Flight 93 National Memorial is planned to include a sculpted grove of trees forming a circle around the crash site, bisected by the plane's path, while wind chimes will bear the names of the victims. A temporary memorial is located 500 yards (457 m) from the crash site. New York City firefighters donated a cross made of steel from the World Trade Center and mounted on top of a platform shaped like the Pentagon. It was installed outside the firehouse on August 25, 2008.

Many other permanent memorials are being constructed elsewhere, and scholarships and charities have been established by the victims' families, along with many other organizations and private figures.

On every anniversary, in New York City, the names of the victims who died there are read out against a background of somber music. The President of the United States also attends a memorial service at the Pentagon. Smaller services are held in Shanksville, Pennsylvania, which are usually attended by the President's spouse.

Final resting place for WTC victims

Some of the World Trade Center debris was sent to the Fresh Kills Landfill on Staten Island. This landfill had been closed to new additions on March 22, 2001, but was temporarily reopened to receive and process much of the debris from the destruction of the World Trade Center. The debris contained the remains of many of the victims; much of it in the form of dust and small fragments. In August 2005, 17 plaintiffs, claiming to have support from 1,000 other relatives, filed a case in court to have the City of New York move nearly one million tons of material to another location where it would be sifted and placed in a cemetery. The lawyer for the plaintiffs stated "It comes down to this: Are we prepared to leave hundreds of body parts and human remains on top of a garbage dump?" A lawyer representing the city argued "You have to be able to particularize and say it's your body part. All that's left here is a bunch of undifferentiated dust."

On October 4, 2010, the United States Supreme Court rejected an appeal by some families of 9/11 victims to require a more thorough examination of material from the WTC site to check for human remains before disposal. They claimed that out of 1.65 million tons, 223,000 tons had either not been screened or not screened adequately, and that a landfill was not a proper resting place for material that may still contain remains of victims. City officials said that they spent 10 months carefully examining the material for human remains before sending it to the landfill. Lower federal courts had already rejected the lawsuit by the families against the City of New York.