Extend Holding Tank Vent Line?

[gcsitts]

The holding tank on my Catalina 34 vents amidship on the port side through a decklevel hole in a stanchion. Odors drift back to the cockpit when it is flushed or sloshing while underway.
Is there any reason this vent couldn't be led aft and vented out the stern? It would add about 20 feet to the vent line.

[Lagoon4us]

Ours vents down to the waterline, it solves also the back pressure issues but needs some thought to fit to a boat that heels....

[GypsyHawk]

A few considerations. The vent line should be as short and straight as possible. The transom has relatively little airflow. A vent pipe and outlet is more effective if it has plenty of diameter ie 1" and if possible 1 1/2".

[GordMay]

Greetings and welcome aboard the CF, gcsitts.

Originally Posted by GypsyHawk

A few considerations. The vent line should be as short and straight as possible. The transom has relatively little airflow. A vent pipe and outlet is more effective if it has plenty of diameter ie 1" and if possible 1 1/2".

You might also add a second vent line, to the other side of the boat. This will improve ventilation, reducing odour in the tank.