What I expected to happen was...:
Being able to control the boat similarly to 1.5.2 version of minecraft.
I place the boat from the beach, right click to enter the boat, press "W" to move forward and then start pressing "D" or "A" to turn. I then press "S" to brake.

What actually happened was...:
I place the boat from the beach, right click to enter the boat, press "W" to move forward and then start pressing "D" or "A" to turn. This did not turn the boat but by looking right or left the boat did turn in those directions respectively. I then press "S" to brake which seems to take an extremely long distance to slow down. Once stopped, pressing "A" or "D" will not turn the boat, and not until I press "W" again and look in a particular direction will the boat turn.
I attempted the boat controls on two different worlds in version 13w19a and was able to reproduce this problem.
I changed back to 1.5.2 on two different worlds and there was no problem.

Steps to Reproduce:
1. Place the boat
2. enter the boat
3. Press "W" to move forward
4. Press "A" or "D" to turn
5. Look left or right to rurn.
6. Press "S" to stop