America's Most Mysterious Ship with Backward Propellers

On a moonlit night off the California coast, a strange and angular vessel glides silently and seamlessly from the side of a massive barge. Her movements are quiet and deliberate, but her unusual shape seems to shift with each passing moment.
At one angle, she appears as a sloped trapezoid; at another, a jagged shard glinting in the moonlight; then, something upright and almost otherworldly, defying every expectation of what a ship should be. But the most advanced sensors, sonar, radar, or even infrared, register nothing.
Her presence is an enigma as if she simply does not exist.
From the early 1980s until April 1993, the United States Navy maintained that illusion. After all, this vessel was the Sea Shadow, America's only known attempt to vanish on the water as effectively as the F-117 Stealth fighter does in the air.