The secrets of Big coils for deep gold!

I have absolutely no idea, but I would like to know.

Also, Woody's article in the latest GG&T about palaeochannels, make me scratch my head and ponder some of those "targets" I've eventually walked away from.

Well kept secrets it appears.

U lost me with that big word.

regards
oneday

The first place to start with hunting deep gold is in an area that you can determine as having deep ground, not trying to be a smart ass, but here in WA most places you go to has relitively shallow ground and many of the big nuggets that would have been around have probably been sucked up already in the early days of detecting.

The chances of you getting big deep gold will increase with a bit of research and making observations as to the depth of the ground, as an example if you have an area that is relatively sparse in vegetation then the reason would be that the ground is shallow to the bedrock and therefore it cant support heavy plant growth, keeping this in mind if there are areas of heavy vegetation growth and also crab holes then you can determine that these areas have greater depth, if these are in or near areas where you have found small gold then there is every chance that bigger pieces are hiding down deep.

Also you have to be geared up for the hunt and set your machine for the task, no point in using a small coil if you are chasing deep gold, big coils are heavy to use for extended periods but with the aid of a hipstick or support harnesss like the new minelab one you can comfortably swing for a few hours at a time, the reason I say a few hours is because the longer you go the more fatigued you become and the less likely you will be to keep you mind on the game, as concentration will play a big part in it also.

You have to keep in mind that unless you are a born "tin ass" that the chances of getting a big deep piece that has a pull you up signal right from the start is unlikely, you have to train your mind and hearing to the more subtle changes and wavers in the threshold, and be prepared to dig and scratch until you have determined what has caused the change, most of the deep gold that I have found has been more or less sounding like ground noise or even just a murmur and unless you are aware of this you can easily dismiss any sound like this and walk away from it.

Also you have to use the right settings for the particular machine you have, earlier machines such as the sd2000 were known for depth, later machines have evolved to be better at finding smaller pieces, a google search and researching other forums will uncover many settings and tips for making depth adjustments, unless you have your machine set for the task you will be wasting your efforts, I have always condsidered that a stock standard sd2000 running on a regulated battery system combined with a good booster/signal enhancer and quality headphones would be as good as you could get, this theory has been backed up by some old mates that have found big deep nuggets in the early days of the sd's.

Anyway use whatever machine you have and try out any settings you can find that will enhance your detectors depth, also be prepared to spend a lot of time for little return and to be digging a lot of holes, but one good find will make it all seem worthwhile in the end.



au-fever

Got to agree with you there AU-I use a 2100 as a back up -slightly modded for easier tuning -and it has very good depth and its bullet proof unlike its owner-Dragon

yep totally agree--
if u r on the banks of the swan or cookes creek and u cant see the bedrock then a large coil will hunt down deeper gold.

if u r in the pilbara and bedrock is in most places then a 8" or 11" mono will surfice but I know a lot of fossickers would rather use a 18x12 or something similar just to cover the country.

hills and gullys that have a lot of schist poking out dont really need a big coil as far as i'm concerned. 11" would surfice. Gullys with a lot of soft material then yes a large coil will enable u to get some depth.

regards
oneday

Thanks for the insights guys. Have a couple of places I will have a look at and play around a bit and see how I go.

Thanks au-fever for giving me reasons to consider what coil to fit. We just arrived home from three weeks overseas and a lazy week down south to recover. I think we'll be home for a while but I've taken some mental notes that make a lot of sense when explained as you have.

I've noticed a few of you mentioning crab holes. What are you referring to?

Crab holes are areas of depressions in the ground, low spots that hold water and become really deep and boggy,sometimes in amoungst trees but also can be out on the flats,they hold water so cattle will congregate in and around them as well.

When dry the cracks can be deep and you need to take care when detecting them as snakes also find the deep cracks and holes a good place to live, One time I saw a death adder sunning itself in amoungst the dry cracks, that was at Bernies Patch Karratha.

The surface may appear cracked and broken forming holes that appear like "crab holes" hence the name crab hole or crab country.

Larger nuggets have been found in crab holes, I suppose that as a nugget is travelling downhill through the ground it comes to a crab hole and sinks down deep becoming trapped there.

au-fever

The problem with ancient stream channels is the gold tends to concentrate in the gut or V bottom of the channel, thereby limiting the detection area, restricting the potential of pinging a target or two. Typical best ground for detecting has the gold scattered about over the flats, gold the old boys could not chase because it was spread too far apart for effective processing of the soils either through dry blowing or sluicing etc (reverse of what we suffer from with channel concentrated gold).

The problem with V bottom gold concentrations is the ground goes from shallow to very deep in only a matter of a few feet, so the potential of hitting a good target is greatly reduced % wise, and V bottom deposits have a tendency of having drop offs in them further limiting getting a deep nugget unless the size increases proportionally. The zone where the ground suddenly drops off to where it's out of reach to the detector is where you need to concentrate with a large coil, the Pilbara and Kimberly's offer a lot more chances for this type of deposit purely because of the amount of water flow these areas experience and the nature of the drainage systems that concentrate the gold. Further south were the ground is more undulating the surface soils tend to hide the deeper ground, one of the reasons why I always swing the largest coil size I can muster at all times, you never know when the ground deepens masked by uniform surface soils.  

JP

I don't have any wisdom to add but would like to say some real good info in this thread, thanks for sharing all.

Gday all
Don't be too quick to write off WA as shallow gold country. Meekatharra, Quinns, Nannine, Doolgunna, Sandstone and I'm sure many other places, have some very deep alluvial. I'm talking metres deep. I pushed a bit of it 30 odd years ago.
A couple of years ago a mate of mine put in some time on a well known, very flogged patch. Running a 4500 and a 18" Coiltek mono in minimalist settings (it was painful to hear the machine) but he knew what to listen for. Anyway, over a two week period he dragged a six ounce and a twenty ounce piece out of the middle of this graded, flogged patch. Both pieces were in the 600-800mm depth range. The ground was inherently noisy to start with and had masked the signals from earlier users.
Next winter I'm going to give my newly acquired 17" NFA mono a good flogging
That old adage about low and slow is probably the best advice anyone can have. Crank up the sensitivity and try and get away from the smoother settings if the ground permits.
cheers
Brett

What a great thread! Thanks everyone for sharing.

Awesome thread guys, thanks to you all for such in depth responses, most definitely has given me a few idea to try,,,, thanks to you all
Happy hunting
Steve, Lea and buddy

i just got some large coils and this thread is just what i was thinking about, very interesting. cheers, roll on next season.

There are many parts of well known and flogged areas that would still hide large deep nuggets, the best patch I found that produced many many ounces, 200oz or more, was in the sort of ground that you would walk over to get to something that looked better.

There was nothing about the spot that would indicate such a large deposit, as a matter of fact a friend that had been in the area some time before even told me that he had detected through there and didnt get a thing, we went elsewhere but a few days later and it had been on my mind that I should try that spot, so going back there for a few hours had me go back to camp with about 4oz, the rest is history.

Long story short the ground looked like nothing but it produced lots of gold so dont get too tied up in working ground that "has the look" sometimes that theory will work against you, as you also have to remember that if it looks good to you it has looked good to the people who have been there before you as well so it would have recieved a lot of attention.

The best spots to try in any known area are the crappy, craggy plain looking bits that others tend to avoid.

au-fever

Au-fever, just goes to show the old WA saying, gold is where you find it,, have encountered what you say often but not with the returns you talk about, ahhhh one day lol
Hope to catch up one day for a beer and a yarn, take care
Happy hunting
Steve, Lea and Buddy

Yep, go slowly over the 'bad' looking ground on your way to the 'good' looking ground as you wander around.
As for big coils, I found when wandering round with the 25" coil that I found more gold with it out to the side or deeper under scrub than actuality deeper directly under it.
The bigger the coil the bigger the all round aura.

Alan

One of the downsides of using large coils, and more particularly on the gpx machines is interference, the bigger the coil the greater the effects of emi.

With this in mind choosing the time which you detect for deep gold is important, my favorite time for this is in the cool of early morning, the ground is cool and calm, and also you will be at your best concentration wise.

Later in the day and as the ground heats up and you also become more weary its much harder to keep your mind on the game, and you are more likely to walk away from some iffy signal that you would perservere with chasing if you were fresh and rested.

Some people prefer night time for this, but I prefer to use the night for relaxation and replenishing my fluid levels,   by the end of the day I know I dont have the concentration span of a gnat so e xperience has taught me that I would be wasting my time, and that I have always had better finds in the early hours of the morning.

Also I would like to add that I still think there is a place for larger dd coils as well, mono's are the way to go for outright depth but the capabilty of a dd coil to handle the ground can sometimes give just enough of and edge to make a signal stand out enough to make you want to investigate it, when it may not when using a mono coil.

I would be interested in say nuggetfinder lightweight spoked dd coils if they ever made any, and also lightweight spoked anti interference coils as well.

au-fever

Interesting topic. Great responses and now I am going to rewrite my Santa list and ask for a bigger coil......does he still deliver to old sheilas?

I thought he delivered to everyone, if they've been good

Good thread, Interesting and helpful replys

Many thanks to all those who provided all the info in this thread it's great & is invaluable advice, with all the info available on this forum in general, I reckon you are well on your way to finding a nugget.

wandwaver wrote:Interesting topic. Great responses and now I am going to rewrite my Santa list and ask for a bigger coil......does he still deliver to old sheilas?

I dont know about Santa but I still do, well I am close to being like Santa all except I dont have a red suit  and I prefer that the girls were being bad during the year rather than being good,   and the badder they were the better the present

au-fever