When I exit a game while standing on a boat and then rejoin the game I spawn on the ocean floor below the boat.

When I exit a game while standing on a boat and then rejoin the game I spawn on the ocean floor below the boat. (Singleplayer)

What I expected to happen was...:
Spawn on top of the boat where I left the game.

What actually happened was...:
Spawened below the boat.

Steps to Reproduce:
1. Move outside of spawn chunks
2. Place a boat on water
3. Stand on top of the boat
4. Save and exit the game
5. Rejoin the game