M8 vs M9 Nugget Hunting

[RSmith]

Has anyone done a side by side comparison of these two coils in the gold fields to see the difference with the smaller (sub grain size) gold flakes?

[Steve Herschbach]

Coil sizes for gold are a trade. Larger coils get better depth on large gold but can lose sensitivity to small gold. Small coils get better results on small gold but less depth on large gold. I see no reason to expect any different with the M8 vs M9. The M9 being round actually is quite a bit bigger in coil area than the M8. I have an M9 on the way but I doubt I will use it nugget detecting as elliptical coils are better for getting into tight spots. If I am after small gold I will use the M8 and if I was hunting larger stuff I'd just jump right to the 11" coil. I suppose you could look at the M9 as being a compromise between the two. For me it is more a beach and park coil though.

This chart illustrates the advantages of small and large coils on all detectors regardless of make. The depth etc may vary but the principle is the same. Note that a small coil can get MORE depth than a large coil, something people generally don't seem to understand in general detecting, where larger always means more depth. Not true.

Another reason I like this chart is that it illustrates a reality of coil use for me personally. Middle coils often have middle results. I tend to always be running a very small coil, or a very large coil. My middle size coils often go unused. If I am after the smallest targets I go for the smallest coil. And when I am going after big stuff, I tend to jump up at least a couple coil sizes from the smallest. The chart illustrates this as the 10" coil actually gets the best depth on nothing. It's in theory the best all around coil though, just depends how you look at it. The M9 is possibly that best all around solution while not excelling at either end of the scale.

May as well mention the M15 coil here while I am at it. If I was hunting tailing piles for lost oversize nuggets, like I did for most of my nugget hunting career in Alaska, the M15 would probably be my coil of choice. Caveat being you need medium to low mineral ground. I'd not use the 15" coil on extreme mineral ground as it will magnify the ground minerals too much. The 11" coil would be the better solution for those areas and large gold.
 

Coil Size vs Depth Fisher Gold Bug 2
Source - Field Testing the Gold Bug 2 by Gordon Zahara

[RSmith]

Thank you Steve,

As always you have given a very helpful and informative response. 

[UT Dave]

Been a minute since I've seen this chart.  It really does very effectively illustrate the paradox of coil size on small gold.

I have all four MC coils.  Wish I had time to do a similar chart with it for my own curiosity.  Life has me steppin' and fetchin' right now though and it won't happen anytime soon.

- Dave

[okara gold]

I have the 9 as well as the 8. Although I'm not in the gold fields I am looking for gold every time I go to the beach, whether it's a fine broken chain or a 1 oz ring. I have recently switched to the 9 inch and do notice I cannot run my sensitivity as high as the 8. About 3 points lower with the 9. The wet salt sand produces more blow back/ noise with the 9. I am using it primarily because it is covering more ground with every sweep and with lots of people on the beach and in the water at this time of year I'm concentrating more on fresh drops. I would think that in any gold fields that are heavily mineralized, the same conditions I am experiencing here would be the same there.