Most manufacturers recommend installing the cooling water discharge above the waterline.
The discharge from the a/c unit should then run to the seawater outlet thru-hull fitting which should be located where it can be visually checked for water
flow and as close as practicable to the waterline to reduce noise
The "water out" thru-hull can be mounted any place on the boat’s hull
that is a minimum of (6) inches above the water line.
The units' discharge through hull
fitting should be between 4" and 8" above the waterline - if below 4" it would have to be treated as a "below the waterline" through hull and would be required to have a valve - above 8" the noise
of the running water may be bothersome.