The bonnets Jon and I posted about would only work on aft-facing hatches. As I mentioned, though, a windscoop used in conjunction with the bonnet over an aft-facing hatch might be a very good solution. It would keep out the rain, but also funnel air below. The Westsail 32 I sailed across the Pacific had an aft-facing forward hatch, and a windscoop blasted plenty of air through the boat. Unfortunately I wasn't clever enough to think of adding the bonnet so that the hatch could be left open even when it rained.

Max