New product -- http://www.atninc.com/dorcap_en.php

The press release says: "The innovative Dorcap is fastened over the open hatch, maximizing the ventilation below deck, and can be reefed down for squalls, rain and changing weather. It is self standing as it does not require a halyard to stand up. It acts as a true dorade. Even if the rain is horizontal, it prevents the water from coming in, while allowing the air to enter the open hatch. Mounts over standard size hatches."

My boat has all hatches forward-facing and no dorades -- it is ventilation-challenged in the rain and this product might be a solution; but I'm not clear about whether it's a good solution. It all depends on how it attaches to the hatch and how it keeps out wind-driven rain, whether it's easily mounted/reversed/stowed etc. It's not cheap either, so it has to be well constructed and engineered to justify the price.