Did some comparision of 11 inch DD and 10 inch elliptical on the wet salt (little long)

[tvr]

Had a week in the Windy Hills section of North Myrtle Beach; hunting was mostly characterized by VERY deep tabs and bottle caps

Most of the week's hunting wasn't with the F75 LTD but I made sure I gave some time to comparing the two coils with the F75 LTD.

Detected about 6 hours with each coil; 3 hours with each coil on two separate days. No rain during the period to dilute salinity. With the 11 DD ground balance would be reached at the last available setting (Zero with no more clicks left) or on some parts of the wet sand one click left. The last time I was in this area (end of last Oct) I was with the 11 inch DD only, and had two of three clicks left to play with. The 10 inch elliptical left me with four or five clicks to play with. Since I only have one of each coil, I don

 

[Scully]

n/t

 

[tvr]

Thanks Scully.

Last fall I read a very short post from someone I respect a lot that the 10 inch elliptical was the better wet sand coil. When I had some time to try the two coils at the same location on the same days; I figured I'd see what I thought.

F75 LTD is a very capable detector in any hunting conditions I've tried it in (once I got past not wanting to use very low sensitivity in high EMI areas); but so far I still prefer my CZ6a or Sand Shark for the wet sand hunting. And I still wish a 3.5 x 18 coil or similar was available for the F75 series as a dry sand and sports field sweeper. Lack of a similar coil for the F75 keeps me taking the Tejon along too.
Cheers,
tvr

 

[Mr.Bill]

When in the wet salt sand. The 10" concentric should be the way to go. I see you discovered that quickly with the easier ground balance. Yes, the bit smaller size of the 10" helps.

Do as best as you can on ground balance. Switch to discriminate mode, and raise it up from the "0" you mentioned until you just clip out most of the salt signals. Hunting wet salt Beach's, one needs to keep in mind that salt is a positive target, just like a piece of metal is to the detector. I wouldn't crank in any discrimination higher than the salt. You may find it gets a little more squirrely if you do. Sensitivity will be a variable setting as the user sees fit to use. Ideal would be right on the edge of stable & un-stable.

Have fun, find plenty of gold jewelry. You certainly have the detector to do it.

 

[SteveP(NH)]

I thought the design of the DD coils inherently cancelled out mineralization better than any concentric coils could. For example this Garrett white paper on search coils (http://garrett.com/hobby/hbby_searchcoil_tech_sheet.pdf) says, " The Double-D configuration is designed to significantly reduce ground interference and, thereby, recover the performance lost by a concentric coil over mineralized soil." Why isn't this true at salt water beaches?

The reason I ask is that I have always spent the money to equip my beach machines with DD coils (assuming that the stock isn't a DD). Is this the wrong approach? I haven't tried my F75 at the beach as I prefer to use my DFX since it is dual frequency but I would think the stock coil on the F75 would cancel out mineralization the beach better.

 

[Mr.Bill]

You are correct about the DD coil, and what it was designed for, but most salt water beach's are not mineralized. The problem with hunting salt water beach's is the "Salt". It's a positive, (+) conductive target. I do believe your considering the salt as mineralization. Mineralization would be a negative,(-) source such as magnetite, or iron ore mixed soil.

Yes, one could encounter both a mineralized beach, along with positive results of the salt. California beach's come to mind. They can be that way in places. Nothing is cast in stone.

If you have both types of coils, you should always test with them the at the places you hunt. But as a general rule, everything being equal if you can, DD coils don't usually perform as well on the salt as concentric coils do. They tend to false more than concentric, have more issues with discrimination, just to mention a couple of them.

Mr. Bill

 

[tvr]

Thanks for the additional explanations and suggestions Mr. Bill!

A little discrimination is the only way I could get the detectors I have that don't have enough ground balance range to balance to the wet salt usable to hunt wet sand. And at that, those detectors that couldn't ground balance to the salt lost depth; some more than others.

One thing I forgot to mention that I observed: when ground balanced to the wet salt sand, sound response to good targets was different. Over the wet salt at ground balance in the 0 to 1 range, good targets respond kind of like bRrrrrr or may be Rrrrrrr; with an emphasis on the leading edge of the tone, but the trailing edge still seemed fairly smooth. Still, the foil and up response is much smoother than the iron or decomposed flaky iron pieces that make the delayed BOING sound. When the ground balance was in the range where I could fast grab it (very slightly damp to dry sand), the sound response is rrrrrr or maybe rrrRrrr and decidedly smoother on the edges than when over the wet salt with the very low GB numbers.
Cheers,
tvr

 

[Mr.Bill]

I have been selling them as fast as they come into stock. Couldn't take one to play with.

I have had exceptional good luck with the new Gold Bug SE at the beach. It's GB range is from Ferrite to Salt Water. The Omega 8000 range is the same, so I suspect it should do well also, although I haven't tried it there yet.

I didn't notice the audio change with the Gold Bug, there again, it GB's just fine. I use Ground Grab.

Mr. Bill

 

[SteveP(NH)]

We have both mineralization (the sand is some spots is purple to black around here) as well as the salt which would explain why everyone uses DD coils around here.