Concave venturi design

Has there ever been a concave (Negative scoop) venturi design in a surfski ? Advantages: Smooth hull profile, nothing to break. Disadvantages: Doesn't drain quite as efficiently ? More labor intensive to manufacture ?

They have invented stuff much better than that, an opening bailer? Smooth hull, zero drag and then drains very fast when open.

Not sure you want a ventury with constant drag 100% of the time, even when empty?

I believe kai waa (makers of the amazing vega surfski) make their outrigger canoe venturis that way. The Venturi cover is flat and the hull is recessed behind and under it. I am not sure why they do not do that on their skis but suspect it might have to do with the need to get center of gravity lower in a ski for balance. To do that the floor of the footwell and the outer hull have to be quite close together. With an outrigger balance seems to be not such a critical issue.

No, If that system were so good they would do it on their skis, and guess what, they don't?

An outrigger has a drop of water to get rid of in the footwell so that system works just fine as it did with skis that had no adjustable footplate. Been there done that!

However a modern ski has huge amounts of water to empty out so a much more efficient system is needed. This involves much more drag to suck much more water out as fast as possible, but with the option of reducing that drag to Zero once empty.

Ranga, you're right about that (bailers). I was interested more from a historic perspective before bailers were the norm.

The original V10 and EVO had a single bailer somewhat similar to what you are asking about. IMO they were useless and had to modify those drains on the ones I had. Obviously, the majority of paddlers prefer the dinghy style bailers (or they just don't have experience with anything else). Sorry Ranga, but, I prefer venturis with bullets. They are very efficient with little drag. Of course I don't care about drag and just want the water out of my boat. And I dare say, an opening bailer has more drag than venturis when open. Opening bailers in sufskis bring thoughts of Rube Goldberg to my mind.

Opening bailers work. They work very well.

I have no idea why you think they are useless. They've been working perfectly in dinghies for decades.

The bailer in my ski works well, drains a full cockpit very quickly.

A bailer has one terrific advantage over venturis; the footwell doesn't fill up when you stop paddling. That really matters in cold climates.

I did not say opening bailers are useless. I was referring to concave bailers. Please reread my post!
Obviously opening bailers are very popular and I recognize the advantage in flat cold water paddling situations. A venturi can simply be plugged in that situation too. I also understand the drag issue. I paddle in the surf and have no desire to be monkeying around with opening and closing a bailer. Opening bailers are a mechanical device that makes them prone to failure or damage. I envision busting one sliding my ski on to my roof racks, for example, if I forgot to close it. Can't happen with my venturi/bullet bailers. I also think that sand might cause a problem with opening bailers? I also believe they are more prone to leaking into the hull/laminate and pretty sure Ranga is very familliar with repairing them? I had an opening bailer in an old sailing dinghy 40 years ago and it worked great in that application. Just don't think that I, personally, would want one in a surfski. I respect yours and others opinions to disagree with mine.

Fath2o

"The original V10 and EVO had a single bailer somewhat similar to what you are asking about. IMO they were useless and had to modify those drains on the ones I had."

Yes, but this was 2005 ish and at that time they were cutting edge until skis like Red 7 started putting bullets on. They weren't useless, they were just less efficient and there was only one of them. Like you, I decided to modify mine. I added a diy bullet and it sucked out the water double-speed. I still use my V10 G1 today and I'm quite happy with how the venturi with bullet performs.