1) The ghost ship north of Nantucket harbor. Over the years I've seen an image of a old sailing ship, like a brigantine, in the same area north of the channel opening in Nantucket harbor. It was always just the rigging, never the hull and the sails were never set. Every time I've seen I was in a boat north of Eel point, or about 5 miles to the west of the harbor. I've thought it could be refraction or something but there's nothing on that bearing from that vantage point until maybe Iceland, 2,500 miles away. The strangest thing was the color of the rigging. It was not just black but pitch black, like holes in the sky. Even though it was always in broad daylight there was no reflection or light at all coming off the rigging. I saw it probably 6 times and each time was from the same area/vantage point and under similar weather, lighting conditions.
2) When I was about 13 I was riding my bike down the street we lived on to downtown to get an icecream sandwich after getting out of school. It was my afternoon routine, particularly in the early fall. The day was a warm, pleasant afternoon. I knew I had to apply the bike's brake just past our house to stop before going into the T intersection at the bottom of the road. The next house down from ours was a creepy 1850s 2-story square concrete house. I think it was part of a business because I never saw anyone come in or out of it and rarely saw lights and there was a printing press behind it. Just as I passed our house and was infront of the creepy house there was a terrific blow to the middle of my back. It was so hard my face almost hit the handlebar of my bike. I looked back but no one was on the street. My bike didn't stop until it had gone across the T intersection and hit the curb on the far side. My back hurt and I was so alarmed I ran straight back to my house. There still wasn't anyone on the street. I ran into the bathroom and pulled up my shirt and turned to look at my back. To no surprise there was a big, red (left) hand print fingers and all, in the middle of my back. To this day I have sustained several injuries in that area including a painful and disabling long-term injury. It was an evil hand to be sure.
Wow! Now, for your first story, I'm thinking some kind of mirage, except you've seen it repeated times. But I think there are cases of reflections over several hundred miles. Anyway, that's very strange. The second story is simply "wow!" Both very good for late night around a fire!
When I was 13, we were vacationing and had taken a night cruise from Sweden to Finland. Being a kid, I was out wandering around the deck with another kid I'd met on out there (she didn't speak English and I didn't speak Swedish but that doesn't matter to kids, right!). It was late twilight, you know, dark but you can still see things. It was the perfect evening to be out stargazing but oddly there wasn't a single other passenger out there but us two kids. Suddenly, out of nowhere, about a 100 feet (I'm guessing here but that's how I remember it) off our starboard side an old sailing ship appeared. It was solid black, just like in your story. No reflection from our ships' lights or anything, just black. It was completely silent. It didn't have the sails up so the masts and everything was very haunting against the twilight. And it wasn't rolling with the waves. I wasn't scared but more like, "wow, a pirate ship!". I stood mesmerized for what seemed like forever but was probably only seconds as our liner passed it. When I turned to my friend to see her reaction to the ship, she was gone. I returned my gaze to the ship, but it was gone too. Needless to say, I ran back inside and down to our cabin as fast as I could.