Riptide is not working to its fullest extent

The site has listed that the Riptide enchantment moves you (4xLevel)+3, resulting in a supposed 15 blocks for a Riptide III. Through testing in clear areas, and making sure I was not hitting mobs or blocks in the pathing, it only takes you 9 blocks at a level 3 enchantment. I have exited out and restarted the game since noticing this and it did not change this.