7,5 or 18.75 KHZ MINELAB 9" ROUND X-TERRA CONCENTRIC COIL for beachhunting

[Michlar]

Hello,
I'm from Denmark - sorry for my bad english:blush:

I normally detect for coins and relics on/in heavy soils. But now I have been on a couple of beachhunts (saltwater-beaches) with my detector....and it is very interesting. But It has only been on dry sand, because my coils are not waterproof. I own a X-terrra 705 with two coils ..... the 7,5 and the 18,75 kHz Double D 10" coils.............. I would like to buy the 7,5 or 18.75 KHZ MINELAB 9" ROUND X-TERRA CONCENTRIC COIL for beachhunting, because they are waterproof up till 1 meter. But I'm very much in doubt which one will be the best on wet saltwater sand......in the surf....and on shallow waters (I hope that you understand me :blush
Which concentric coil should I go for ??
Regards
Michael Larsen, Denmark

 

[Digger]

Any of the frequencies will find coins. But for beach hunting with one of the two you mentioned, I'd recommend the HF 18.75 kHz coil due to it being more sensitive to small gold jewelry. However, depending on where you are able to ground balance your X-TERRA with the two DD coils you have, you might find the areas are too highly mineralized (black sand) for a concentric coil. To determine if concentric will serve your needs, take note where you are able to properly ground balance either of your DD coils. If you are able to ground balance them at the beach with a ground phase reading in the mid to upper 30's, you should be OK using a concentric. (although it will provide a lower number on the ground phase reading). If the ground phase number when using one of the DD coils is in the low 20's or less, you might find the concentrics just won't neutralize the mineralization effects of the sand. In that case, you should stick with a DD coil. One possibility you didn't mention is the new Coiltek 15-inch DD, which is waterproof. On the other hand, if you don't have high concentrations of black sand (high mineralization), the concentric should do fine. JMHO HH Randy

 

[7centsworth]

Here is a post that Digger posted about which coils are and are not waterproof. http://www.findmall.com/read.php?55,1068029,1068029#msg-1068029

 

[Michlar]

Okay....I think that I will go for the 18,75kHz concentric then. we don't have high concentrations of black sand (high mineralization) at the danish westcoast, so I hope it will work. I have just heard some rumors about the 7,5kHz concentric working a bit better in salty conditions............but I supose It was only rumors??
regards
Michael Larsen, Denmark

 

[David]

But remember all single frequency VLF machines(like the X-Terra's and all others) do not work as well on wet saltwater sand, but do work very well on dry saltwater sand.

For working best on wet saltwater sand use a Fisher CZ, Minelab BBS-FBS, or any PI machine which gets the best depth but poor discrimination. My first choice for wet saltwater sand in high junk-trashy areas is a Minelab BBS-FBS machine.

 

[Michlar]

Okay
regards
Michael

 

[Digger]

Granted, the metal detector industry makes specific models for specific types of hunting. But don't think you have to spend another $1000 or $2000 on another detector to be a successful beach hunter. The X-TERRA 705 has functionality that has proven to be a winner. The key is to know how the hunt the beach. This involves understanding how mineralization differs between dry sand and wet sand, knowing how to adjust the X-705 for the site and how to physically hunt a stretch of sand, to get the best results. The salt water in wet sand intensifies the ground mineralization, compared to the same sand when dry. This not only requires a change of ground balance. But will also require that you lower the Sensitivity when hunting in wet sand (compared to what you might run in the dry sand). Here is a post made some time back, by Barnacle Bill, regarding the use of the X-70 on the beach. The 705 will react the same way.

http://www.findmall.com/read.php?55,653711,653711#msg-653711

In conclusion, my suggestion would be to hunt parallel to the waterline, sweeping the dry sand separately from the wet sand. Doing so will allow you to maintain settings for longer periods of time. Set your 705 to Tracking Beach. Tracking Beach will maintain the appropriate ground phase setting and updates quicker than regular Tracking. If the detector starts to chatter, slow down your sweeps to allow time for the ground phase settings to keep pace with the changes in the mineralization levels. Overlap your sweeps by 1/2 when using a concentric coil and by at least 1/3 when using the DD coils. Practice various methods and write down what works for you. If you come up with any "magic" solution, don't hesitate to let us know what it is!

HH Randy