Therefore most dredge permits refer to the nozzle size, not the hose size, when imposing rules and restrictions. The volume of material processed is determined by the nozzle opening, not the inside diameter of the hose. A 5' dredge may have a nozzle opening of 4' for this reason. However, nozzles are used on dredges which restrict the intake to a size smaller than the inside diameter to help prevent clogs. So a 5' dredge has a main suction hose with a 5' inside diameter. Manufacturers rate suction dredges by the inside diameter of the main suction hose.

Floats are also needed because there is rarely a nice gravel bar in just the right place to set up a dredge without floats. Every inch of vertical lift above the surface of the water robs power/suction from the system. This is because a dredge has just enough power to lift water and gravel to just above the surface of the water. Dredges almost always need to be mounted on a set of floats. A sluice box works because gold is 15 times heavier than sand and gravel and so is easily trapped by the riffles and carpet in the sluice box. Material is transported from underwater to the surface and run through a sluice box to capture the gold. VORTEX removal rates are ACTUAL removal rates as seen with actual material moved using Magnetite black iron sand and rocks weighing 2.375kg per liter as to the sample product.A suction gold dredge is basically an underwater vacuum cleaner. VORTEX performance figures DO NOT have a small print clause with an Asterix symbol next to figures which would represent 'best case Scenario' removal rates as opposed to actual removal rates. Suction does the work and water flow continues the work done. Once the hose is clear then water flow takes over. Powerful, simple, effective.Įxample: Getting a 'RIDICULOUSLY THICK MILKSHAKE' ® ™ to move through a straw is similar to dredging a very sticky seabed and suction is key because if you drive a suction hose deep into sticky mud the water flow in the suction hose will often stall and the hose is essentially filled with a 'plug' of mud and only high suction will clear the hose. Vortex dredges have been designed to combine high suction values and high water volumes to tear up sticky soils with very high suction then keep it flowing with high water volume.

2 inch dredge with suction nozzle