If riding a boat, crash into a tamed dog, next hit land, and finally turn a lot, you end up dying. Why?

I was seeing if a dog could come in your boat like Minecraft PE. So i rammed my boat into the dog, and then hit land (dirt block). Right when I hit the land I started started to turn a lot. Next I thing I know i'm dead. It said, "Closetdoortb has hit the ground too hard."