Waterproof Pulse Induction Detectors Compared

[cudamark]

22 hours ago, Steve Herschbach said:

Only five years later, over half the waterproof pulse induction models are gone. Tesoro Sand Shark, Garrett Sea Hunter, White's Surfmaster and BeachHunter, all gone. Rumor is that the ATX is on the short list to being discontinued. SDC even though it is "waterproof" is really is not a submersible beach PI. Amazingly we are pretty much down to the Fisher Impulse AQ (now at $1999) as about the only new with warranty option left on the table. Sadly it is held back by never being fully realized as promised with the so-called Limited Production model being in eternal production, the newer version died on the vine. Maybe the new Nokta Pulse will help a little, but the reality is that the new multifrequency detectors have all but killed off pulse induction beach detecting. With that in mind maybe Fisher can be forgiven for not putting any more effort into the Impulse AQ.

Calling the Impulse AQ waterproof is stretching the definition a bit too. You get neck deep and drop it, and it ends up beyond the rated depth limit. I'm wondering how the GM2000 will do in salt water.

[The Lama]

On my beaches there are a few days a year where black sand is deposited so thick usually up against a cliff or seawall where the water changes momentum the black sand can be so pure that smf is worthless ,a couple years ago in one of these situations we were killing it in the less black sand 10 feet downslope and somebody noticed 2 coins on the surface an nox,legend and an apex couldn't hear luckily i had an infinium in my truck and i killed it on the pure black sand but my point is on my beaches the pure black sand is deposited high up so waterproofing is not so important  

[Steve Herschbach]

1 hour ago, The Lama said:

On my beaches there are a few days a year where black sand is deposited so thick usually up against a cliff or seawall where the water changes momentum the black sand can be so pure that smf is worthless ,a couple years ago in one of these situations we were killing it in the less black sand 10 feet downslope and somebody noticed 2 coins on the surface an nox,legend and an apex couldn't hear luckily i had an infinium in my truck and i killed it on the pure black sand but my point is on my beaches the pure black sand is deposited high up so waterproofing is not so important  

Ocean currents create surface and subsurface deposits of magnetite in the water. Old beach lines also exist offshore in many places, created when water levels were lower (anyone doubting this, Google up on the Nome beach gold deposits). These underwater areas are patchy and move around continually as currents alternatively expose then bury them.

The nature of these newer SMF detectors is that they are subject to “silent masking” when encountering these patchy conditions. In other words, the detector goes dead temporarily and the operator does not even know it. It’s too bad they don’t have an overload feature like the 24K and some older detector models, that literally squawk at you when they overload.

But yes, I agree, the worst stuff I have seen is on the higher beach. That’s partly due to the gold pan like winnowing action that takes place on the beach, but also due to the wind blowing off lighter sands, leaving the heaviest behind. This can’t occur underwater obviously, and so over time the high beach can reach extreme concentration levels you won’t normally see in the water.

The high Sierra Mother Lode country has decomposing magnetite rich serpentines, where the surface soils are just beds of magnetite with a little non-magnetic stuff tossed in. Kills VLF/SMF. I remember one spot in particular where I looked on in amazement as my VLF called a 30-06 brass shell casing sitting on the surface a ferrous target!

From my long post here, quoting the master himself, Bruce Candy:

"In geologically new soils, the degree of mineralisation is usually weak, except for some volcanic soils. These relatively new soils are commonly found in North America and Europe (from glacier scrapings during the last ice age and mountain erosion etc). In contrast, surface soils which have remained surface soils for a long time often have high mineralisation, because the action of water, over a long period, causes iron compounds to migrate to the surface. For example, Australia has old soils, having had no glaciers recently or significant mountains to be eroded. Some volcanic rocks or sands, known as black sands, may be highly mineralised and are found, for example, in a few USA mainland and Hawaii areas. These black sands (or rocks) are made of mostly magnetite, an iron oxide called ferrite. These typically produce almost entirely X signals, and almost no R. They are heavy, that is they have a high density, and can be identified because they are strongly attracted to a magnet. Small roundish magnetite/maghemite pebbles (a few mm in diameter) are also attracted to a magnet. These, for example, may be found in many Australian goldfields, but do produce significant R signals. Thus, USA goldfields are typically different from Australian goldfields:

The USA soils are mostly mildly mineralised but in some areas may contain either nearly pure magnetite black sands or rocks, which  are problematic for metal detectors as they have very high X components (strongly attracted to magnets).

Australian goldfields have highly mineralised soils, but very few black sands or rocks that contain nearly pure X magnetite. (Emphasis added) The magnetic materials are in the forms of magnetite-rich small pebbles and rock coatings, clays and general “sandy” soils. These all contain magnetic materials that produce high levels of X signals as well as R. The ratio of X and R is random, and the R component arises from extremely small magnetic particles called superparamagnetic materials…”

 

Long story short people who have never encountered this sort of stuff have a hard time understanding what is just old school common knowledge in gold prospecting circles.

[Tony]

Sad to see the demise of a proper 30+ foot depth rated beach pulse detector but detectors like the Manticore have changed the playing field for many coral based sand beaches. My rebuilt White's PI3000 (don't laugh) is still needed for a few locations that are subject to magnetic black sand "infestation".....certain spots fill with black sands that are the result of winter storms and heavy swells that appear to draw in the black sands from deeper water. The Excalibur just "nulls" constantly and you'd be lucky to find a ring an inch or two down into the sea floor.

There is a market for someone to launch a "fit for purpose" beach pulse detector....keep it simple in a robust (clear) enclosure with three or four controls.

 

[Tony]

If I could go back in time 25 years then I'd beg, borrow, steal to buy a few of these units.

All you need is two controls in a very reliable underwater case (Ikelite).

Jim Pugh......we need you back !!

 

[Joe Beechnut OBN]

4 hours ago, Tony said:

White's PI3000

My friend ED still has his old PI 1000's and the other a 2 or 3000 in the yellow. He's a Nox user now. We had a guy at the club that used one up until he passed about 7 years ago. He would hold it with both hands with the machines coil flat on the bottom moving it left to right and back

 

Had a friend give me a Barracuda, the battery was shot.. made a battery for it, weird voltage like 8 volts?, Had the AQ so I gave it to another friend, Steve Noga. I should have shot video of the compare I did using it.. No doubt build like a tank with the ikelite case.. Jimmy shared many notes and pictures when I asked for info on it.. I think new they sold for 699.? , a great machine for its time. 

[Tony]

I finished my rebuild on the PI 3000. Runs perfectly and gets 12" on my wedding band....not too bad for a 30uS delay. 

Black sands and moving salt water doesn't alter the smooth audio.....and the enclosure were made by Ikelite and a screw down end cap can't be beat for keeping water out.

 

[Tony]

1 hour ago, Joe Beechnut OBN said:

I think new they sold for 699.? ,

$999......according their website. I remember the Aquastar (Eric Foster) was just over $2000 back around the same time 1999-2001. Baracuda was well priced.

[Tony]

Joe.....Eric was working on a new Aquastar prototype before he got sick. I think he had most of the PCB sketched out. It was going to be mounted in a high quality enclosure from Blue Robotics. I was going to test the unit for him once completed. Sadly the project was never finished due to his illness.

https://bluerobotics.com/product-category/watertight-enclosures/locking-series/