Hi there,
The same concept is used on sail boats and also power boats...
They do work - they also can allow small amounts of water to get in to the bilge... so sail boats that are racing use them because they usualy take water on board in rough seas regardless and this lets it out which means they have less in the bilge than they would if they didn't have the self bailing bungs.
The ultimate is an electric bilge pump.
The same concept is used on sail boats and also power boats...
They do work - they also can allow small amounts of water to get in to the bilge... so sail boats that are racing use them because they usualy take water on board in rough seas regardless and this lets it out which means they have less in the bilge than they would if they didn't have the self bailing bungs.
The ultimate is an electric bilge pump.