The water was only 2 feet deep where I was working, but the old venturi did not have had that sort of power.

The result was great, power increase was such that the water and gravel came up the hose with such velocity at high rpm, that it shot right over the sluice box and landed back in the creek 2 feet beyond it! I had to slow it right down to be able to wash the gravel. I will try to load 2 photos showing what I came up with. I used alloy for weight reasons, but also because it was what I had on hand. I lined up the new 3/4 inch jet to be slightly pointing downward but up the center of the pipe - so the water jet would hit the bottom of the pipe about 3 or 4 feet up. Mostly because my hand wouldn't fit up past the nozzle restriction. The old shop bought venturi had worn totally out and was very hard to get jammed rocks out of. My pump is a 5 hp Honda driving an Onga pump - a factory built pump/motor unit available here in NZ. The last one was four inch and I used a 3/4 inch jet with a flare out to the 1 1/2 inch supply. Hi there, I have made a few suction venturi nozzles over the years, as I couldn't find or couldn't afford store bought.

Gold dredge suction nozzle