Gravity dredging

What would stop a gold prospector doing this in the arrow river,nothing mechanical about it.


Yea iv had the same idea Siphoning the water with gravitational push and the river flow doing the work a .

At that wee dam that is full of gravel? Has to be a shitload of gold in there…

Several pissed off claim owners would likely stop it…

Not on a claim I’m talking about the public area


I do not think you would get enough fall without a huge long length of hose would you?

Yea but it makes perfect sense to gravity dredge 0.8grams of gold with $6k of 4inch dredge hose. Let the clown go try it and be disapointed

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I had a look on YouTube and found a guy in Taiwan doing it in certain spots with good vacume and bugger all hose .if I were to try it il use 110mm unpunched drainage pipe 30m $277 few floaty devices or coke bottles .ribbed hose just let it run for an hour after "dredging"an clean hose out .get the right creek an you’d get 2 -3mtr of head no worrys in under30 mtrs of hose .

Sounds like the go,and I dont need to do this nor will I try was a mere suggestion, im happy dredging with my 5 inch elsewhere, I’d use pipe like you said not dredge pipe as some other clowns reckon.


imagine getting a blockage half way down 30 m of hose , with stuff all suction , that be fun


Lol have tried this in arrow not enough drop in river worked little bit but would need abt 25m+ of hose i used 10m

Gravity dredging will be a waste of time in most situations. I’ve tried it myself yep. In summary I used a 30 metre length of novaflo. You’d be better off with pvc lengths of downpipe like they used on gold rush White water. The trouble with flexible pipe is it will pop up from the forces at work over and over again even with rocks holding it down. In concept gravity dredging is a sound idea just not too practical in most situations. Youll need a lot of gold to make it worthwhile. The pipe will get blockages in the bends. The main thing is the length needed and you’ll be working an area with good fall so lots of back and forwards. Really a 2 man operation as the work area will be out of sight of the sluicebox. I’d do it again but would limit it to a small waterway with small gravels and low volume of material to move. Was fun doing it at the time.


It’s consider “hydraulic dredging” still not technically legal because any action where material is moved other than by hand is considered mechanical in nature. Not organic.

Is saying that I have used it. It works but use a cage and limit how much material goes down the tube. All material displaces the water therefore lessoning the overall vaccume.

I was looking into Gravity dredging and it seems like if you could get it to work it could be great fun. I cannot really find much on it but is the system just get a long pipe with a sluice or something at the end and put it on an angle in the creek so all the water goes down with a high force so it pushes all the gravel down with it? And wouldnt it be possible even with lets say a 5 or 10M pipe if the creek had enhough of a drop eg you had it set up on the top of a water fall? I was just wondering as I thought it could be a fun experiment to see if I could get it going .

And would this be super a efficent way to set it up? with the arrows= the rivers flow at the surface, so you have the top of the dredge set up just at a pool for example at the bottom of rapids and dredge into the higher up gravels above? Wouldnt that give it tons of power as you would have the dredge on an upwards angle and be at the bottom of a steep drop in the creek.

Cheers any further info is appreciated.

Last year we started dredging just above a drop of with no room for the dredge so plonked it in the pool below and ran the hose up over the big boulder, pools had about a 1.2m hieght difference and with a 4 inch keene the engine just ran at idle as any faster would blow out and you couldnt pry oversize stones off the nozzle, it had plenty of suction without the motor but just not quite enough flow to run the triple sluice. A single stage sluicebox id say would work perferct.

You dont need much fall to make it work well but bear in mind a long hose would be a bitch to unblock jams, heavy when full of water and youd def want to limit bends etc to reduce blockages.
10m max i rekon before it got too much of a handfull and that would severly limit your options to dredge. Would be ideal for small mountain streams with steep gradient or plunge pools.

Procrustean bed… The productive approach is to choose the technique to fit the location, not vice versa.