I read a Guardian propaganda article on Apple News (https://apple.news/AbaQ6QQX7Qr26t56dMSNItg) about a guy seeing a ship hovering over the water off Cornwall. It tries to explain it away as an optical illusion using "science". Supposedly, air temperature differences were bending the light, but that makes no sense, especially given the lack of visual distortion around the ship and the visibility of the bottom of the ship, which would be partially hidden by the water if it were floating normally. While the ship looks awfully normal to be a high-tech hover-ship, this does seem to hint at the possibility that such technology secretly exists, and the ships are disguised as conventional ones. Why it is kept secret or how it works, I cannot answer, though I would image a nuclear powered ship might at least have the raw energy output needed.