Well Rick, you and I both know how duckbills work, I just simply can't remember how 161 had her cockpit drains set up. I know the 23 Cat has (2) 2" drains in each aft corner in the cockpit sole in molded-in drain channels, but the were pretty standard 90s running to t/hulls on the hullside...
What we DO know is that the skinny end of the duckbill has to be oriented towards the hullside t/hull. I don't believe orientation is a concern, vertical, horizontal, whatever. For instance, head pumps (manual or electric) have duckbills to prevent waste from coming back in the toidy. Orientation is not an issue...