Rails Riversurfboard

Hey Guys,
I’m landlocked and started shaping 2 years ago. I shaped some nice boards but i can feel that there is something missing. I read a lot of theories and stuff about the hard/ soft rails and in the sea it all makes sense to me. What i was thinking about was, that if there is no upstream/ lift necessary from the rails in a stationary wave in a river, why do all these boards still have soft rails? In general (at rivers) the floatation is given by the surface of the board and the speed of the current right?!
A typical riverboard shoud be very manouvrebale and fast, which is in my opinion better with hard or even sharp rails like a kite/ wakeboard. Would be great to know what you guys think…

General informations of the boards i usually make: 5’2"-5’4"x20 1/2"-21 1/2"x 2 1/2- 3’’
Fish shape wih a wide round nose.
Tail is usually about 12-14" wide.

Hopefully you got some nice ideas!

Match the shape of your board to the “shape/slope” of your standing wave.
The dynamics of surfing are still the same (see PM).