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Garrett ATX Review - Beach Detecting In Hawaii


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Hi Jim,

Thanks for the comments.

As far as discrimination goes never use more than needed so if you are getting along fine without do not use it just because I did. Out of water there should be little or no need for it but getting the coil into salt water or over saturated wet sand may produce signals best eliminated by bumping the disc up a notch or sensitivity down a notch. You just have to play with it and experiment.

I recommend not using weights unless absolutely necessary and only if you have the proper training or experience. I am a certified SCUBA instructor, with dry suit, zero visibility, and night diving certifications. I've spent thousands of hours in the water weighted up on SCUBA or on hookah systems in fast moving water. I have a very high comfort level handling myself in the water in extreme conditions..

I am leveraging that experience by getting into 3-4 foot surf break that without weights would simply toss me up onto the beach. It is pretty much all I can do to stay put with weights to keep me on target in the surge.

The weight belts do have quick release buckles and can be ditched in seconds if need be. More on Hawaii detecting including photo of me geared up with a suit. https://www.detectorprospector.com/magazine/steves-mining-journal/garrett-infinium-kaui-hawaii-gold-jewely/

The truth is if I had more time I could get into those areas anyway by waiting for calmer water and most people should do just that. And there are certainly other places I could and did work that were mellower, more protected locations. Never ever exceed your comfort level and know your limitations in the water because drowning is a real danger.

Number one hazard as far as I am concerned - surf and boogie boarders. When they are in the water I always know where they are and stay away from them. A tourist on a surf board is a missile out of control looking to knock you cold if looking down and unaware. And with weights on it is down you go, gurgle, gurgle, game over!

I have my hands full working in surf so duck to the bottom and fan and the weights hold me on bottom in place. I am basically breath hold diving for several hours. A more sensible situation is to just work in mellower conditions using a long handle scoop, mask and snorkel and no weights. Ease into it and under all circumstances stay safe. A suit may be needed but adds buoyancy also which again tends to necessitate weights if attempting to reach bottom. So wading and a scoop are the best option for nearly everybody.

A couple book favorites:

ADVANCED WATER WORKING TECHNIQUES by Andy Sabisch

http://www.sabischbooks.com/books/general-th-ing/

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HARDCORE BEACH HUNTING by Gary Drayton

http://www.garydrayton.com/New_Sovereign_book_.html

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You want to see some eye popping finds check out Gary's blog at http://hardcoretreasurehunting.blogspot.com

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Thanks Steve, great info to consider.  I am comfortable in the water, lots of snorkel experience, but I'll try some shallow water hunting first, without weight belts. I know of one Laguna beach area that is usually protected from waves from offshore rocks and kelp beds and many swimmers snorkel there (including me) to check out the Garibaldi and other cool fish. I hunted the short section of beach there and found a lot of coins so maybe it has not been hunted much. The sand is only a few inches deep, underlayed by marble sized gravel. 

   On the ATX settings I did notice a big change as soon as I transitioned from dry sand to wet sand. On the wet sand the ATX made a slight whine noise at the end of each swing. Next time I will try increasing the discrimination just a bit and perhaps I can then increase the sensitivity. It is fine either way, but I would prefer to run the machine as quiet as possible. I can always throw down a ring and listen to how it sounds against the background. The coins have been a great experience to learn the machine, but I am really only interested in the rings or jewelry. 

   Again, thanks for the great tips and links,   Jim

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There is a lot of resistance to getting detectors set to run quiet because it involves reducing settings that reduce sensitivities.

On the beach it is common to encounter what you have described. A tone at one end of a swing. Usually it is when walking parallel to the beach and on the downswing to the water. The sand is getting wetter in that direction, and the increase in salinity produces a signal.

The real problem is on the upswing. The autotune/automatic threshold circuitry is trying to keep a steady tone going. On the downswing it is working to suppress the tone. When you swing the other direction the circuits lag catching up and the machine will go dead quiet. The detector now in effect has a threshold that has been set way too low, and any faint targets encountered on the upswing will probably be missed. The downswing is not an issue as much as you are basically supercharging the threshold but a faint signal can also get missed in the midst of the overall signal.

It has been hard for me but more and more I am setting my detectors to find the hottest setting that gives quiet, even performance, even if that in theory dumbs the machine down. Tuning too hot in theory lights up a target that might otherwise be missed but then again it may still get missed because it sounds like noise. In the end it is up to the engineer to deliver a detector to me with enough power that when properly tuned it gets the results, and the ATX does just that.

The Sensitivity works by reducing overall target response while the Discrimination (pulse delay) acts first on tiny low conductive targets. Reducing Sensitivity will reduce the response on both a gold chain and a large ring. Increasing the pulse delay can cause the same gold chain to give a reduced response but have less impact on the response from the ring. So increasing the Discrimination a notch may be more beneficial with rings than dropping the sensitivity a couple notches. Notice in the owner manual excerpt below reducing sensitivity is the last suggested option.

Finally, the ATX does now have a ground balance circuit that can run into the salt range. This means you can use the ground balance to eliminate salt effects while leaving the Sensitivity and Discrimination at the most sensitive settings. This is being billed as having the capability of eliminating the salt effect while retaining sensitivity to more gold items.

I honestly am still sorting out which combination of settings works best on which targets but in the end it is something you do want to experiment with yourself. Anything you discover would be a great help if you post about it. You can be sure I will do the same.

The pulse delay is measured in microseconds and on a Whites TDI the control runs from about 10 uS to 25 uS. I do not know what the range is on the ATX but it is similar. Short delay times light up tiny gold but also light up saltwater because both respond the same. To be good on small gold nuggets the ATX has to have a short delay range, but to work in salt water you must be able to adjust the range higher. From PI guru Eric Foster at Link deleted since Findmall update broke all old links

"A delay of 10uS is the best for sensitivity to small gold jewellery, but dropping back to 15 is not going to dramatically affect the sensitivity except for things like ear ring studs, very thin chains, broken rings etc.

Two things that do affect the shortest pulse delay that can be used are the salinity of the water, and the nature of any wave action. These two factors are interdependant, as wave action in more saline water will give the greater effect. Certain places on the coast have the sea water diluted due to river outflow, and here the effects are much less. The nature of the beach can also have an effect. i.e. the ratio of solid material to water; underlying clay or bedrock, and any iron mineralisation present. Some detectors do not have an adjustable delay and this would limit their flexibility.".

Long story short reducing the Sensitivity or increasing the Discrimination (pulse delay) and the Ground Balance or a combination of any of them to eliminate that downswing signal is a good idea. Or, work straight down to the water and then straight back up along with slower swings can keep the effect under control to a large degree.

Garrett ATX Owner Manual page 28

Saltwater Operation

When mixed with water, salt and other electrolytes become conductive and may therefore cause any detector to respond as if the saltwater were a metal target. In fact, to a detector, saltwater has an electrical conductivity very similar to foil, fine gold and other poor conductors.

Traditionally with pulse detectors, to address the saltwater response the Delay/Discrimination setting was increased until the saltwater response was sufficiently eliminated. This method, although effective, can significantly reduce the detection of fine gold, jewelry, and other poor conductors due to the increased Discrimination setting.

Therefore, to help reduce this undesirable loss of detection, the ATX has an alternative method to address saltwater. Specifically, the ATX can automatically ground balance out the saltwater response without the need to increase Discrimination; thereby maintaining a better response to fine gold, jewelry, and other poor conductors.

The two methods to address saltwater are:

1) Ground Balance Method: Leave Discrimination set to minimum and Ground Balance to the saltwater as would be done for any other ground. This method will provide the best detection of fine gold, etc., but will produce a low-tone response for all targets. It is important to Ground Balance the detector when it moves to a new region of the beach (i.e. from wet sand to dry sand at the water's edge).

2) Traditional Discrimination Method: Incrementally increase the Discrimination setting until the saltwater response is sufficiently eliminated, typically around 3–7. Ground Balance is not required with this method. This method will maintain normal high and low tone responses, but will have reduced detection of fine gold, etc. Reduce the Discrimination setting toward zero when moving from wet sand to dry.

For either method, the following basic techniques will help to achieve the best performance:

1. Swing the searchcoil flat and at a constant height. Do not bounce the coil or lift the coil at the end of swings.

2. Hunt the three different regions of the beach (dry sand, wet sand, submerged) one at a time rather than going back and forth between regions.This will allow the detector to be set optimally for each region.

3.Swing the searchcoil parallel to the water's edge to minimize changes in moisture levels within a given swing.

The detector may become less stable in shallow, breaking surf where the searchcoil is in and out of the saltwater. In this area the detector is encountering a constantly changing environment produced by the surf, making it more difficult for the detector to stabilize. Experiment with the two methods above to determine which you prefer, and if necessary, reduce Sensitivity to obtain stable operation.

Excellent post by Eric Foster on same subject Link deleted since Findmall update broke all old links

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