Last Post 13 Jan 2015 03:57 PM by  William Hall
Dredge Adjustments
 3 Replies
Author Messages
Lester Kemble

12 Jan 2015 06:21 PM
    I have a 2" Keene Dredge with a crash box sluice on It. When it runs the weight of the water brings the end of the sluice down near the water. That point is can be adjusted by moving the sluice on the dredge frame. Question is how much or how many inches should the end of the sluice be above the water?
    New Member
    New Member

    13 Jan 2015 06:24 AM

    This is what Keen uses for there 4" dredge it should be close for all and it does not heart to have the sluice box end in the water you should go by what the material in riffles look like. there should be about 3/4 of the riffle with black sand and small pebbles with larger pebbles down stream from the riffle with a small patch of expose carpet in front of the next riffle it should look like that after you stop running material and let the water run for a while


    Most models have a slight adjustment to raise or lower the sluice box. The proper sluice box adjustment can effect the

    recovery of values. If the sluice does not have enough angle, the sluice box will "load up" causing the riffle openings to

    fill with unwanted excess material. Too much angle will cause the material to flow too fast, resulting in loss of values, evidenced

    by the riffles running too clean. The optimum adjustment of a properly working sluice box is evident by only a

    portion of the riffle is visible while operating. A loss of values can also occur if the solid content of the suction discharge is

    too heavy in solid content. Remember, the solid content should not exceed 10 %. A normal sluice box tilt is approximately

    3/4” inch to the running foot. Afour foot sluice box should have an approximate tilt of 3"


    13 Jan 2015 10:24 AM
    There is no one setting that works for all dredges. You will want to run you're dredge as flat as possible while still clearing the lighter material from the riffles. This will change depending on the mass of the material you are working.
    William Hall

    13 Jan 2015 03:57 PM

    The modern Keene's 3 stage dredge box will run slightly in the water. You cant get the end of the box outa the water and maintain enough slope to clear behind the riffles as explained in the previous post.

    Old style dredge boxes whom ever the manufacture, you want the end of the box out of the water just slightly to keep the end of the box from loading up, but not to much, as the higher you lift the material the less suction you have at the end of the hose.
    Keep the box as low to the water as you can, but still keeping the end of the box outa the water.
    Its a balancing act. Each time out will be slightly different.
    Don't worry to much on startup, once the box fills with material and water is when to consider adjustments.