Gold Hog - Riffles
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Breaking down the riffles…
Do I REALLY have to write this myself? Hey, where did
everyone go? Figures, they leave when the tough part comes.
OK… here it goes.
We spent hours and hours and hours setting up riffles, recording them, and
then watching the results in slow motion. At first we wanted to figure out
the “best riffle”, but then we realized this was the WRONG concept or idea.
How could we POSSIBLY “figure out” the BEST riffle if we didn’t know what
the REAL JOB of a riffle was? This is where our study takes a slightly
different turn compared to others.
Ours takes a slightly different turn because we wanted to start with a
“blank slate”. Most people think that a riffle is designed to “hold gold”.
After REALLY observing what happens under water and in slow motion,
we think this is the WRONG way to view it. We think you should view the
riffle as a “working machine” within your tray / sluice box,
not a “storage or holding center”.
If you learn nothing from our work except this point, learn it and learn
The REAL JOB of a riffle is to create a “working zone”. This WORKING ZONE
has many parts, behaviors, and actions. This working zone uses some
gravitational pull, but this is also increased by the PULL DOWN or THROW
DOWN of the working VORTEX the riffle creates. So, look at the figure below
and tell me what area is the most important. Pick a range of 5
The “conventional wisdom” and what people look at most
often is the 1-5 range. You’ll often hear something like, “My riffles are
holding a bunch of materials and that’s good. “ However, this logic has its
flaws after watching ALL the material work around and into this “working
zone”. Does the riffle actually “HOLD GOLD”, I GUESS you could say it
appears it does and YES gold will be found tucked in behind the riffle , but
again we think that thought / concept should be viewed a little differently
and expanded upon. We’ll explain it later in a CRITICAL
called the WORKING ZONE.
CRITICAL THOUGHT… often not discussed…
Proper spacing, Gold’s Energy, and the WORKING ZONE.
(Here comes another curveball.)
How does gold fall? It falls fast, very fast. That is true and it does this
because it is VERY heavy. However, when you “LAUNCH IT” off a riffle,
it also has a great deal of energy / velocity /momentum which allows
it to travel farther than most materials.
You can get a better “visual” example by thinking about throwing a ball.
If you throw a wiffle ball with all your strength it might go 20 – 30 yards
before gravity forces it to earth. Now throw a baseball the same way and it
can travel a 100 yards easy. Throw a wiffle ball into the wind, it will
stop quickly. Throw a lead ball, the same size as the wiffle ball, into the
wind, the wind will have little impact on its travel. This starts to get
into “linear momentum”. Linear
momentum is a measure of an object's translational motion. The linear
momentum “p” of an object is defined as the product of the object's
mass “m” times its velocity “v”.
(Think we read this off the side of a beer can somewhere.)
So, rather than being a “stationary object” falling faster than the rest, it
now is a “fastest, heaviest bullet” with longest range. So quite often,
LARGER gold will hit the matting between 9 and 14. (Behind the vortex)
Smaller gold hits it anywhere from 5-14. Quite often the materials that are
being pulled directly into the vortex and washing behind the riffles,
initially, are lighter materials as they are easier to grab and move.
We mention this observation because a LOT of people are
moving their riffles closer and closer together. Sometimes this distance
can be too close. This sometimes causes the gold to ride the top of
vortexes like a downhill skier bouncing mole hill to mole hill. (We've
recorded it on video, not guessing.)
on our observations and testing….
There seems to be a “rule of thumb” out there that spacing
riffles should be based on Rx2= S (open space). So, if you have a 1” high
rifle the spacing would need to be 2” of clear space. Our observations found
this to be totally wrong for MOST setups. (Based on the fact that NOT all
heavy material is PULLED down by the IMMEDIATE vortex.) Much of the heavy
material falls at the rear of it, just beyond it, or even significantly past
it. Even a ½” riffle can demand a 2.5 - 3” spacing to make sure the gold is
being exposed to a “working zone” and POTENTIAL capture by matting /
settling. If you followed the Rx2=S formula, the spacing would only be
about 1”. If you have a good water flow and speed running, a ½” riffle can
produce a working zone of over 2.5” alone. If you want the material to
settle before hitting the next riffle, then you need to add a bit more.
The RULE OF THUMB we came up with is that EACH sluice box is different, so
there is NO exact rule of thumb. Again, we must rely on
“Kentucky Windage”. Pitch, water speed, amount of water (volume) will also
impact this setting. However, from our recorded observations we believe
(opinion) that it should be in line with Rx5=S . So a ¾” riffle would
have 3.75” of open space. A 1” riffle would have 5” of open space, a ½”
riffle would have 2.5’ of open space. Again… it will vary and you need to
test, but one thing we found is that Rx2=S, does not work well and sets up
for gold losses.
There is a TON of more info we collected about this
process, but for now let’s leave it there. We just want you to “get that
picture” in your mind.
When you speed up gold, it has the potential to travel farther than other
materials. Hence the “fast falling” theory really is often
overridden by linear momentum.