Allow me to chime in with my two cents worth: I've raced many, many high performance sailing dinghies, and most of them had cockpit drains. They work very well, assuming you are moving along at at least the pace you should be achieving in a racing kayak. The faster you go, the faster they drain. And, assuming you're going fast enough, they'll suck down any quantity of water - in due time.
Most dinghies don't ship an entire boatload of water on board, though, and the ones that might often have cut out flaps in the transom to drain large amounts of water. In a Laser - or a Force Five - (both of which have mere footwells) if you aren't going fast enough for the bailers to work, one just frantically "kicks" the water out of the cockpit.
Regardless, with a standard sized kayak cockpit full of water, you aren't going to be paddling fast enough for a drain to work! I daresay they would drain off the occasional wave that makes it's way inboard, though.

If you want to bail a well sloshed cockpit - and still keep on racing - I heartily suggest a battery powered pump. They are pretty small, cost about $40, run on 3 "D" cell batteries, and are fully submersible. Just flick it on and get back to racing (or, more likely, trying to stay upright!).

Dave

: Donald
: Thanks for the information. Since you have actual experience with a drain in
: a boat... Can that drain in your Force 5 empty the entire boat if it is
: fully swamped? if so, how long does it take, and how fast do you have to
: go?
: Thanks
: Mike