WASZP Ventilation Fence

The WASZP suffers quite a lot from foil ventilation in colder water.
In the Netherlands i experience foil ventilation from ~october up to mai/june.

The main vertical as well as the wand are leaving a "foamy" trace.
A ventilation is induced once the water/air mixture hits the front of the rear vertical at a certain level under water. The air gets washed downstream along the vertical and causes a flow seperation at about 1/3rd of the vertical. The flow seperation itself moves down the vertical at slightly tilted angle towards the back.

Any rudder movement certainly doesn't help to prevent ventilation. 
I did a quick Ansys CFX Simulation to better understand the issue.

• The maximum possible rudder angle should be somewhere at 25°. I've chosen 7,5° for the simulation as a reasonable rudder input.
• Flow speed is 7 m/s (13 knots)

I believe the low pressure zone helps air, that was hitting the vertical at a certain depth anyways, to travel a litte bit deeper towards the horizontal before initializing a flow separation.

I tested this ventilation fence this spring and was really happy with the result.
The worst you get is from time to time a “half” ventilation down to the fence which is easy to shake off and doesn't cause any loss of control if you chose to ignore it.

I recommend to print it with TPU and 100% infill.
I have chosen a scale factor of 99,9% for a nice tight fit.