Most rowing machines in gyms are set too "hard" water resistance does not mimic the setting most people use.

There is a rotational aspect in two planes no rowing machine i use mimics: the rotation around the oar gate, an arc of about 120 degrees, as you move forward and backwards, and the throttle twist of feathering the oars.

These limit the utility of dry rowing to me.

I've rowed in a static tank and its more "real" because your push is against water (you basically circulate water in a tank) and you get both feathering, and rowlock plane rotations

(In real rowing, your arm sweeps out a circular arc of the radius from the rowlock to your hands)