Open 60 sailboats have a pedal-looking control in the middle of the cockpit. Does anyone know what it does and how it works?
It is a 'on-station grinder', a centralized station for turning the winches of the sheets (lines) attached to the clew of a sail. They are multi-speed, meaning you can have a serious mechanical advantage (5, 10, 15, 30:1) under dire conditions that a 2-speed winch with a handle simply can not work unless you have Arnold on board. And even then...
Generally used on 9-meter, 10-meter, and larger racing sailing vessels. Generally now they are hydraulic.
It is a winch. Which is used to generate a larger force needed for bigger boats. What it actually controls is not entirely clear.
My best guess would be it's for the main halyard (to raise the sail) or at least something to do with the sail. Looking at this picture the man is looking up at the sail in harbour while using the winch in question. So I would guess he is looking how high he raised it.