Boats act abnormal in regaurds to certain rotation commands when the player is riding them

/execute @e[type=boat] ~ ~ ~ /tp @s ~ ~ ~ ~90 must be run twice in order to work, and will then turn the totaled 180 degrees

commands which use actual coordinates for rotation do not work at all, unless the player relogs

ex:  /execute @e[type=boat] ~ ~ ~ /tp @s ~ ~ ~ 45