a gray disk with a shinny rail on which a wheel turned

on a fishing trip while drinking coffee i stood on a porch observing the lake i felt apressence behind me i turned and saw a gray disk approaching at a very slow speed about 100ft. above me .the disk was headed west to east with a slight wooble.it was about 10 meters in length and 4 meters high.the top of the disk rotated in both clockwise and counterclockwise directions.the top of the disk rested on a wheel that was on a rail of what appeared to be stainless steel.this rail was very bright in color,very shinny.the  bottom had three 7s which were inverted, three bars of equal length which appeared convex.the disk proceeded to the end of the lake dipped right and peeled off and down to the left and disapeared behind trees at the far end of the lake.
Date is approximate.  Witness elects to remain semi-anonymous.  PD