Here’s some great solutions for keeping the air flowing in and out of your boat this summer. 
Thanks Carolyn Shearlock.

Port Visors

For those of us in rainy areas, Port Visors allow us to keep ports open in all but the nastiest squalls. Admittedly, in nice conditions they may block a little airflow, so you have to balance how often they’ll improve ventilation versus how often they’ll restrict it. Port Visors are made of UV-resistant Lexan (it’s practically unbreakable) and come in a variety of shapes and sizes. There’s no metal to rust, and because they attach fairly easily with adhesive, there are no screw holes that have to be sealed. They’re permanent, and they’re tough enough that lines slide off them. Another advantage is that they have a bronze tint that provides some shade — it’s sort of like wearing sunglasses. They won’t block all splashes, so you’ll still need to close your ports in most conditions while the boat is underway.

Simple Exhaust Fan

An exhaust fan is a wonderful thing in a galley or head, but most are through-deck, not very efficient, and not safe for offshore journeys. The Basic Port Fan is cheaper, quieter, requires virtually no installation, and can be put away in bad weather. It requires only about 6 amp-hours per day on low when running full-time, and it’s rated for 70,000 hours — that’s almost eight years of continuous use. This fan moves about four times as much air as a computer fan, and it can be positioned to pull in air from the outside or exhaust the interior. At five inches square, several can be mounted around the boat for good cross-ventilation. Position the fan using bungee cords or hook-and-eye fasteners, then run the 6-foot cord to a cigarette lighter or 12-volt plug, or hardwire it. There’s no hole in the boat to leak!