There was once a product called a 'Sudbury vent" which was a water-trapping
ventilator made of a tough clear plastic, hemispherical in shape and maybe
12" diameter. Has anybody seen them in the market?

dave wrote:

Hi all !

I have in my barge a bended roof top in plexiglass (approx 3 meter by 5,
4mm) with sometimes condensation dripping from it. I have been looking
for a while for a ventilor (aerator) to let the hot air escape (looked
at Lewmar, Goiot, many shipshandlers...) and could not find what I am
looking for :

a small aerator (in inox, aluminium or plastic), with an internal
diameter of 4 or 5 cm and external of 5 or 6. Preferably, I would like
sometime that holds itself with the aeration hole, without need for
other holes for screws.

I could only find aerators in alu / inox 10 cm or bigger with 3 screws.

I tough that what I was looking for could be found on any sailing boat
but....

Any hint, provider, .. much aprreciated !!