I just improved our ventilation by replacing my Nico vent with a new one. The new model has a sleeve inside which can be extended to make the seal very watertight from waves washing across the deck. This Nico is in our head. Right now the day/ night Nico are on sale at WM ( $40 off)
and cheaper than anywhere else
In addition we also bought a seperate Stailess Dorade from Vetus * was so impressed with T37Chefs I had to get one) and installed that with a mushroom vent inside/ under it which can be tightened down from inside the boat and makes it waterproof.
Thanks t37chef--is your head forward? How sensitive is it to spray/water over the deck? I'm not clear on one thing from your post--did you sintall the dorade with the day/night vent, or were these separate installs you're talking about?