This BBC report contains video proof that HMS Endurance, called a ship here, is actually a boat!
The point is in the Royal Navy’s definition. Sailors get extremely upset (yes really, if you are not a sailor) when you call their ship a boat. I’ve done it in conversation in playful annoyance to see the wincing reactions from my nautical chums.
The Royal Navy definition it that a boat is something that can be carried by a ship. Check the video. It’s a boat.