Coil choice for SD2100

Hi all,
Not sure if this should be in this section or the SD2100 section.
Looking for recommendations for a coil for my SD2100.
It has been suggested that the area I'm in would be best detected with an 18"DD and am happy to get one of those but I thought, before I purchased, I'd see if people experienced with these detectors had alternate views.
BTW Monos are out of the question in the area I'm looking.
I'm currently using a standard 11"DD coil and am looking to achieve greater depth. Unfortunately, the area I'm detecting has mainly small nuggets, 1- 3 grams, and would like to be able to detect them but still retain the capability of detecting another "Welcome Stranger"
Any feedback welcome.

Thanks in advance
Terry

Hi Terry,
The problem you have with DD coils is that the bigger you go, the less sensitive they are to the smaller nuggets, but you do increase your depth. So it's a fine balance to get a compromise for both situations. If you had plenty of time, you could comb the area with the 18DD for the deeper possibilities, then recomb the area with the 11DD for the smaller possibilties, or maybe look at a 14DD which gives you a bit of both, extra sensitivity than the 18DD and more depth than the 11DD.
It all depends on the area you are working, and it is a little hard to specify a particular coil for your needs without really knowing such things as depth, scrub cover, range at which nuggets have already been found, etc, but a 14DD is a good alrounder but the 18DD should still give you slightly more depth.
Hope that somewhat helps
Cheers

Thanks CostasDee,
Thanks for the reply, I do appreciate the play off between depth and sensitivity... been doing far too much reading.
The person that recommended the area would be best suited to an 18" DD has good experience in the general area and has a good eye for the lay of the land. I guess my real concern was that they are an expensive coil and I'd hate to purchase one and find it wasn't a great deal of use in other areas where the 14DD may be a better long term choice given its weight advantage as well as better sensitivity for less depth.
So while I really respect his advice, I'm in a bit of a quandary.

What would be your best guess at the difference in depth between the 14 & 12"?.

Hi again Terry,
It's extremely hard to give exact measurements in inches when it comes to depth because as the soil composition varies, so to does the depth of penetration (I am talking about coil depth penetration here guys). For example, in a very quiet are with basically topsoil. you may find you might do down 30" but with the same coil in heavily compacted and mineralsied ground, you might fid you only go down 8".
I think we have to work in percentages here and these are only my rough guesses and not exact facts. If an 11DD is equal to 100% (in depth) then I would expect an 17x11DD to be approx 135%, 14DD to be approx 145%, an 18DD to be approx 170% and a 24DD to be approx 225%. Now as I said these are my guesses and observations and may not be quite true to what happens in real life, so please treat them as such.
Of course, weight is an issue, cost another, ability to move amongst scrub is another and footprint on the ground, another.
Cheers

Thanks Costasdee,
good subjective information.... mucho food for thought, so tempted to get the 18" but still a major purchase.
I will ponder at length...... and then prob get the 18" LoL

Thanks
Terry

The Commander 15x12" dd is the best all-round dd I've used on SD's. Seems a to be a real sleeper as they dont often get a mention on the forums

I agree with you NuggInOne, and I've often thought of adding one to my list, but they are slightly heavier in comparison to the Coiltek 14DD and they dont often come up 2nd hand at a reasonable price, but if one did, I would add it to the arsenal.
Cheers