Impact and Black Sand

[Sven]

Most of our beaches here in Ontario Canada has sand with magnetic black sand mixed in.
Some popular beaches here seem to never give up the goods, coins and jewelry. Everyone always figured the beaches were cleaned out, there are many detectorists who hunt them.
And we also thought people were just not losing much, keeping valuables locked in their cars.
One beach in particular at one of our club meetings, they say is littered with garbage rarely make any good finds.
We did take a Sunday drive to that beach for fish'n chips. Noticed how darkish gray the wet sand was.
Now just for giggles took home two big 7-11 size soda pop cups filled with sand about 100' in the dry sand from the shoreline.

Here's what I found that could shed some light on the lack of finds complaints.
Took a few detectors, ground balanced over the sand. In all metal mode, they all picked up the 6" gold ring, and US nickel. Switch to disc mode, not a peep. One detector with a very slow sweep using a 5" DD coil, a one way click.
The Impact in all Di modes 14khz, 5x9 coil, not a peep. Switch to Deep mode, it will pick up.
Most people will hunt the beaches in disc mode to knock out foil and maybe more, for the most part the detectors cannot punch through the sand, missing most if not all targets that are deeper than 3-5". If in all metal mode, those people who hunt in it, will find goodies----maybe!!!!!! Or just junk?
Why, seems the sand is causing a wrap-around effect. You will only see this happen if you are using a target ID metered screen. All silver to gold will be downgraded in target ID numbers close to the iron range. All the targets that would normally be in the iron range get wrapped around back into the high target ID numbers that silver and copper would normally ID at. Would report with a high audio tone as well.

Now that has me thinking, hunt these beaches in All metal mode or a disc mode that does penetrate using the Impact. Listen for the low tones and low ID numbers. Then get ready to dig treasures....? If this is the way these beaches should be detected, then detectors with a customizable program could be set up.

Any thoughts on this?

Or just get out there with my PI, that punches right thru these sands of gloom.

Possibly what I have found out can help others who have similar conditions.

 

[squirrel1]

When you say you switched Impact to deep mode and it starting picking up gold ring 6" deep, did the detector just give iron tone? Or a nonferrous tone?

 

[Sven]

Any modes that the Impact picked the ring up in skewed ID numbers to iron as well as a iron tone. My other detectors had similar results.

 

[Mudwhale]

In New England we have bleached white sand beaches that quickly turn to Black magnetic salt water sand at the tide line. The only hope here is COG mode. I have used this mode away from the beach just to get away from some very hot areas with EMI and possibly burnt coal dumps.

 

[squirrel1]

Any modes that the Impact picked the ring up in skewed ID numbers to iron as well as a iron tone. My other detectors had similar results.

Thanks Sven.
Anytime I see someone talking about high minerals I try and pay attention.

 

[Mudwhale]

COG mode works great here! This mode ignores black magnetic sand in a huge way! It ground balances at 0 versus the default. It is also the weapon of choice with extreme hot ground and areas with harsh EMI. It's in the machine...USE IT!!!!!

 

[Sven]

Just rec'd a water hunting book Water Hunting Secrets of the Pros Vol. II by Clice James Clynick. CJC member on Findmall who also has an Impact.
The book by the way makes excellent reading.
He actually had a write-up on black magnetized sand, he mentions disc mode hunting is really not the proper mode to hunt in. And that all metal mode should be used, lower sensitivity, focus on the short consistent target sounds that stay still.

As you mentioned try COG mode. As I mentioned scan thru the Impacts modes to see which one works for you. The Di modes did not seem to work as they are discriminate modes. Any of the modes that were all metal based worked. The Impact does seem to have many bases covered with what its able to handle in the way of different soil conditions.

 

[Mudwhale]

Went to the shore this evening where white sand quickly tuns to black wet saltwater sand. The Impact went a little noisy the closer I got to the black wet sand. When I got over the wet black stuff the Impact got too noisy to hunt with in any mode. The mineral scale was at 5 bars. I switched to COG mode and all the noise was gone. I re-ground balanced and I found a silver ring and a 1964 silver half dollar. COG mode is the only mode to use when the gound is really unstable.

 

[Tom Slick]

You said it got too noisy to hunt in any mode. Then you said the noise was gone in COG mode. Sounds to me like the Impact worked very well in COG Mode so your first statement was incorrect?

 

[Mudwhale]

Sorry for the time delay..WORK!!!

Yes, when I got into the real black sand here in CT, which is the entire coast line, the Impact would not settle down in any mode I chose. All I got was a lot of EMI soundiing chatter and noise. It Was very distracting and I decided to switch to COG mode according to the manual. The Impact went silent after I ground balanced it and all was good from there on. This is only the third time I have had to use this mode. Once was a coal infested site and the other...I don't know but it worked. The COG mode uses the 0-15 Iron scale... JFWIW....

 

[Tom Slick]

"the Impact would not settle down in any mode I chose" except the Cog Mode.

 

[Mudwhale]

DOH! I meant except for COG mode. Sorry for the confusion! Normally I stick to DI99 and DI4. I tried GENd mode, DEEP, and the VLX modes and they were too chatty. I tried shifting the main frequencies and tried the frequency shift feature in the menu. COG mode ran well here. I am suspecting that a combination of strong EMI together with the black sand is the culprit in places here. The CT coastline is riddled with all kinds of buried utilities, cell towers and underwater cables.

 

[cjc]

|I actually put a bit in my new book about hunting black sand in all-metal mode--just listening for anything small and consistent--it works. With the impact the slowed down response of Deep Mode does quite well. By it's nature this machine is already inhibiting inconsistent responses. I run up at 97 and dig anything with extention--my "blunt instrument" mode--works great!
cjc

 

[Mudwhale]

Thanks for the info! I tried DEEP here and got more EMI noise than any other mode when I tried it. EMI is apparently a killer in places here. Cog mode has worked for me here.