To those wondering. This is a exploit cstg and them are using. In order to to this bug.
Have a group of people each holding a sail. Do a countdown and have each person place a sail at the same spot. If done right you can have 2 sails in the spot of one glitched without the ship sail unit points. I figured its better to post how to do it instead of reporting it because devs reads reddit more than their support tickets.
This is broken when done on schrooners...you can go 35+ knots. Obviously we did it just to test we are not using the exploit ourself but it is broken.