hi Scott,
what I learned about leadcore, I learned from Brad Juaire on Mille lacs. If you have not already read ALL his reports, even back a few years; there is a wealth of info he has written.
You should also plan a day SOON and get out there with him with a few friends. You will learn all you need to know in one day.
But to get you started:
It is 30 feet per color. The older original #18 pound you get 5 feet per color, and the newer 832 suffix lead is 7 feet per color (smaller diameter).
It is easier to add backing, leadcore and leader to a larger capacity line-counter reel, but counting colors does work, but line counters are more accurate. You get bites, you want to duplicate that on all your rods in the water.
The previous poster was right that speed does change the lead depth. Brad runs at 2.0 mph.
Use a 50 foot mono or floro leader.
here is an example, water depth is 32′, and you have fish arcs 2′ off bottom in 30′. You would want to have your lures about 2′ above the fish, so you need to have your lures at 28′. You need to know what depth your lure goes on the 50′ leader, use a lure depth/dive chart to find the depth of your lure at 50′ leader length, let’s say 10 feet; so 10 from 28′ gives you 18′ depth you need to get to with the leadcore. I have the older #18 core (that is 5′ per color) so that would be a little more than 3 1/2 colors of leadcore out to get your lure to near 28′ feet down.
If you have the line counter, that would be
50′ for leader, LC 3 1/2 colors at 105’= 155′ total on counter to get your lure to 28 depth.
Same example with newer #18 LC (7’/color)
50′ leader, 2.6 colors 78’= 128′ on counter.
Hope that helps,
Jack