Question - setting up a 5 feet long sluice?

[Joel1316]

I was just thinking... If a sluice is 5.5 feet long, it would go with theory of a 5.5 inch drop (angle).
If it has a 5.5" drop, it could mean that the end of the sluice is completely submerged under water?
Is it OK, to have the end submerged (water overflowing the sides)?

 

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[Jason in Enid]

Yeah, it's OK. You wouldn't want it to be too far under, but I would imagine that it shouldn't be too bad. If you are having material pack up in the end, then you may need to do some adjusting.

 

[russau]

the distance of the drop is really determined by the material your working. you need a decent drop to washout the unwanted bigger material. but if you screen the raw material youll endup not needing a step drop in the sluice. why would you need a 5.5 ft. long sluice? and the 1 inch per foot of sluice is ONLY a starting point! it may be less than that or more!

 

[Joel1316]

I've seen a home made sluice on a local ad and it was 64" long. I was just thinking how to set this sluice up in the river.
Good point, if I classify down to 1/4" and have good water flow, may not need the 1' /1" angle...

Thanks guys!

 

[Goodyguy]

I was just thinking... If a sluice is 5.5 feet long, it would go with theory of a 5.5 inch drop (angle).
If it has a 5.5" drop, it could mean that the end of the sluice is completely submerged under water?
Is it OK, to have the end submerged (water overflowing the sides)?

That's one reason why you don't want a sluice that long..... the submerged part will just be wasted sluice due to the inefficient clearing of the riffles, mat, etc.

Tests have proven that friction slows down the flow after the first few riffles and because of that for maximum efficiency the riffles should decrease in height and be spaced closer together as they progress down the sluice or else they are actually working against a uniform flow. The longer the sluice the greater the disparity in flow from front to end. Meaning if you have the flow adjusted right for the first half the sluice the second half wont be and vice versa.

Tests have also shown that in spite of poor riffle design, spacing, angle, flow, etc. gold can still be captured but not without significant losses.

http://hecklerfabrication.com/files/sluice-build-partIII-2.pdf

http://www.goldgold.com/setting-the-proper-water-velocity-through-a-sluice-box.html


GG~

 

[Joel1316]

http://hecklerfabrication.com/files/sluice-build-partIII-2.pdf

» Setting the Proper Water Velocity Through a Sluice Box


GG~

Great read n the goldgold.com site. I will use the idea of using a plastic tarp in an elevator dam (faster/easier).
The other link is quite long, I will download it and read this weekend.
Thanks!