If it's not blowing, cowl vents aren't enough in some conditions.

At those times, you want to open the overhead hatch in a cabin. These look like small dodgers to me, the type you used to see more often on older boats covering small companionways or even large hatches also used for getting below or handling large sails.

If you could open your overhead in say a veeberth without a drop of water falling below, that would be a nice improvement to any boat.

With that thought, I would expect them to be a little pricey. Imagine having a dodger built for your hatch(or would it)? What do they cost and is the installation simple?