Much more elegant job than the 'bu, these are basically interceptors mounted vertically rather than the horizontally at the transom.
The transom hook on the prostar functions in much the same manner as these do. They allow for earlier separation of flow from the hull which has the effect of creating a bigger hollow behind the boat.
Although these are still going to have the same problem as the surf gate in that they will cause the boat have to be continuously counter steered to remain on a straight course due to the increase in pressure that occurs right before the interceptor.
I attached an image that shows how it functions and the resulting larger hollow.
Credit for the figure is to Hydrodynamics of High Speed Marine Vehicles