The best place for ventilation system that will keep Exlex Minor dry inside even when upside down is on the main bulkhead. Like always on a small ocean going yacht things interfere, like the waterproof hatch, the storage etc as well as the incoming air and the outgoing air that has to cross each other. Also the opening for incoming the air and outgoing air be as far apart as possible so that the incoming air does not get sucked out before getting into the boat.

To help me sort out my thoughts I used the mockup in 3 dimensions and two ropes one twisted one braided. By giving them a few extra bends I figured out how to install the ducts. – Each bend reduces the airflow so I had to make as few as possible. Where I made a bend I increased the channel diameter to compensate.

To new readers the system works on the principle that water enter the ventilation channel cannot rise above the sea level. Hence the ducts start by crossing the boat athwartships then descending to as far as possible.  That way whatever angle of heel, even upside down some part of the ducts of both the incoming air and the outgoing air is always above the waterline, thus blocking water from entering the boat. See earlier posts and illustrations.

Below a picture showing how the ducts are bendt.

Below showing in detail the extra bends of the brided rope.

Below a picture of the main bulkhead. The thin lines indicating where the door to the sleeping room is, is probably to thin to been seen.

The below illustration is by Pierre Herve showing the slightly different ventilation on Exlex. Thanks Pierre.

To bee continued…

Regards Yrvind