Hull unit (hoist)
An omni sonar term, in plain English.
The motorized unit that raises and lowers the transducer through the tank.
See it in action
The free lessons show where this shows up on a real screen: start with the learning path, try it yourself on the omni trainer, or look it up on real CSH-10 captures in the field guide. Owners and captains talk settings every day on the forum.