At or about 2300 hrs. during the summer of 1987 or 1986 I was on my boat anchored at Haverstraw Bay, just South of the Indian Point Power Plant, in New York. I noticed an object in the sky moving South at a very slow rate of speed. It displayed four spotlights evenly spaced along the front of the object. The object was silhouetted against the night sky. What amazed and puzzled me, that based on based on it's rate of travel and it's altitude, it should have fallen out of the sky to the water. What puzzled me further was that it made no noise. It reached a point which was almost directly overhead when it stopped forward movement, turned at proceeded back in the direction in which it came, finally disappearing from site. At the time of this sighting I was a Detective Sergeant with the Ossining New York Police Department.