I have a ski with venturis. My Fenn doesn't have the 'trailing bubble' like the picture posted. When you sit in the ski, water comes through the venturi holes and fills each footwell a few inches. when moving at any decent speed, the water flowing past the venturi creates a pressure difference, pulling the water down out of the footwells through the holes. I don't know how it would work on a 'hollow' kayak, it would just simply fill the entire boat with water. If you added a solid bulkhead/seating arrangment, it would only fill that area up to some point. Most surfskis are now made with one footwell which can create a problem with excess water filling up in that bigger space. Surfskis like my older Fenn Millennium have split footwells which reduces the amount of water that fills when sitting still.

I suppose you could also make the seat area drain by running a hose from a hole in the seat to the venturi drain. But I also suppose it would be rendered useless by seat pads, plastic bags, big rear ends, etc.. and that's why you never see that option.

Like I said, the boat has to have buoyancy, and if you just drill a hole or two in the bottom, it will sink. Here's a Van Dusen kayak, which is a hybrid kayak with surfski style bucket. It has some sort of venturi style drain that I think you can actually close if you want.

Eric

: Does anyone know how a venturi drain in a surfski works? and if one could be
: retrofitted to a kayak like my Mystery. In some of the races I do, a fair
: amount of water enters the cockpit, but I'd rather not wear a skirt. I'd
: rather not wear a skirt because of the heat and/or I'd like the option to
: exit quickly due to strainers on high flow rivers.
: Thanks
: Mike