They are Anderson mini bailers. Most surfs skis have a fixed venturi. Hole with shroud to create a low pressure are to allow drainage once up ti speed. Epic use the anderson mini bailer in their V12 but retain the fixed venturi shrouds for their V10. I agree with Bill, the mini bailer would be perfect for an open cockpit boat that won,t be used in big conditions.
i have just finished gluing the sheer clamps to my latest project, a surfski using a clc pax 20 hull. As i don,t intend to use it in big conditions or for open water racing, I am considering the mini bailer as well. However, i am a big fan of the Red7 bullet scuppers.