use double scuppers. They make Scupper drains for cabins below water level that will drain but not let water in with a hose. Just put them in your deck then run a line out the transom on both sides and put scuppers over the lines so incase the set on the back of the boat get stopped up you have a back up in the flor too. Look on
www.boatfix.com for them. They will have a good but reasonable set. Here's a link to see the below water line deck drains with scupper balls.
http://www.saveabuckmarine.com/produ...?sku=232-CSD92
use these in the deck and these on the transom for double safety.
