Self closing freeing port

I need a source for a self closing freeing ports, preferably in aluminum, to be used for unloading deck water. One possible source is Fraser Bronze. Anybody know of other sources?

 

Most folks call them scuppers; therefore, you might do an internet search using terms like "automatic scuppers" or "self-closing scuppers" or "self-bailing scuppers" or something to that effect.

Wouldn't be too hard to fabricate something like a small boat fender laying horizontally in a cage, that would float up and close the scupper when underwater. However, you would have some ugly appendages sticking out the sides of the boat.

 

Thank you village_idiot. Your suggestion is excellent. A fabricated aluminum box, mounted with the outboard side flush with the boat side, and just below deck level will work.