She was definitely talking about the partial-drowning water wheel and not the limb breaking wheel.
But instead of getting attached to the edge, the Ero version has you attached to the side, spread-eagle. A vibrator or other sextoy is placed on or in the victim's genitals, then they are rotated so only the upper half of their body is submerged in water.
The victim is then forced to hold their breath the entire time while resisting the orgasm, because if they do they'll subconsciously let out the air and start drowning. After enough time they're rotated out to catch their breath, then the cycle starts over again.