Boat velocity changes in 14w32b

When you build the boat lift and use it in 14w32b or 1.8+ or 1.9+. It's doesn't work properly. But in the 14w32a or older boat is working properly.

Please see this video.
Testing on 14w32a : https://www.youtube.com/watch?v=fhz6zsBzNz8
Testing on 14w32b and 15w36d : https://www.youtube.com/watch?v=4xaz-IH7y0k