Where to put solar vents in C&C 30 MkII?

[serpa4]

The C&C 30 has 4 opening Lewmar hatches; two in the cabin, one in 1/4 berth, and one in the bathroom. My boat is 2000 miles away and cannot verify it though. I just bought it.
I would like to install solar vents to move air and control humidity.
Where should I put them? Here are my thoughts.
One in the bathroom due to showers and higher water use. One in the /14 berth to keep the temps cool and fresh air supply. And, finally one in the cabin. I think I need to avoid the large port over the V-berth due to water intrusion while sailing to weather, noise over the berth while sleeping, and finally, perhaps I might on occasion cover the port for darkness while sleeping and the vent would be covered.
Anyone know what size vent is needed as I don't know the Lewmar hatch dimensions or material (Plexiglas?).
Anyone have a better recommendation on the quantity and locations?
Thanks.

 

[Benny17441]

Nowhere near the bow of the boat where water could reach. We were sailing an h34 off the coast of New Jersey on which someone had installed dual vents by the bow hatch and the weather started turning on us. Before we could reach safe port we dipped the bow a couple of times into rather large waves which resulted in a cascade of water coming down inside the cabin. Checked them out to see if they could be closed but could not figure it out at the time .