Hand Dredging

[HowardE]

To make a dredge, you could probably do it with PVC. Look at this design, and basically replicate it with PVC. Diving Equipment Specialties

The key to making the dredge work is making a venturi elbow above the suction nozzle. You could probably assemble that out of a trap from a toilet drain.


While using a scooter does work for uncovering larger items, its MUCH MUCH slower than dredging. Even if you use a relatively low GPM pump to power the dredge system, it makes good suction if you create the venturi properly.

 

[fire_diver]

Frogman, there isn't any "fine tuning" to the dredge head. The suction nozzle is bent at about a 45 degree angle, and the pressure line is bent in a "U". It should force water into the middle of the suction tube, and aimed straight down the tube. If it is aimed at the sidewall of the suction pipe, it will scour a hole in it. The pressure tube on the nozzle is actually necked down slightly from the pressure line that feeds it. And the suction tip needs to be rolled inward to restrict the opening about 25%. Otherwise, rocks, large shells, etc can create plugups in the line.

Are you planning on using it as a recovery dredge, or just with the discharge line weighted down outsite the excavation site?

 

[billblack]

You might take a look at this thread on Treasurenet:http://http://forum.treasurenet.com/index.php/topic,74871.0.html

 

[Gilldiver]

1) Make sure that the suction end is smaller than the ID of the pipe so you can't suck anything into the pipe that will get stuck.

2) None of these designs have a vacum breaker flap so that you can break the suction at the nozzle to get rocks and other things off the nozzle without shutting the whole system down. This is a great feature if that "other thing" is one of your hands.

 

[Falconpilot]

I have always wanted to try this.. Just to get a feel on how it works.. I know its not very efficent but cheap has a quality all its own..\

Air Lift Device

Dennis

 

[mrmagoo560]

To make a dredge, you could probably do it with PVC. Look at this design, and basically replicate it with PVC. Diving Equipment Specialties

The key to making the dredge work is making a venturi elbow above the suction nozzle. You could probably assemble that out of a trap from a toilet drain.


While using a scooter does work for uncovering larger items, its MUCH MUCH slower than dredging. Even if you use a relatively low GPM pump to power the dredge system, it makes good suction if you create the venturi properly.

We have used a larger system like this for years in the oil field to "jet" the cuttings out of our suction pits.It works real well but sucks up everything,you will need some way to inspect the discharge to make sure nothing is blown out with the debris.