Length of line to sinker?

Sorry, but I have another newbie question    When using a three way swivel or sinker slider, how much line do you put between it and the sinker?  Do you mark fish on finder, and make length equal to the distance the fish are from the bottom?  Does it depend upon fish type?  Are bottom feeders actually at zero depth?  How far from bottom do fish in kelp hang out?

As always, thanks in advance for your advice.  Now that I'm hooked on yakfishing  , you gotta feed this addict   

It really depends on what you are fishing for. I don't use a lot of 3 way setups unless I am halibut fishing. Then I try to get it as close to the bottom as possible without getting tangled in the grass etc...

Setups vary with the target species and structure.  Generally, fishfinders are utilized for finding structure and bait not to target specific fish.  Using a 3-way over a reef with no kelp I'd go 12-14 inches of 10 lb test for the sinker and 3' or less of 30-40 lb for the business end.  In kelp I would direct tie to a torpedo and run a couple of dropper loops above, having a hot bait on a long leader will tangle up in the kelp.  Keep them baits on a short leash.  I'll only run a slider set-up when on the pick or drifting sand, they actuall tangle alot less than the 3 way.  

Different fish will reside at different depths.  Typically school fish like blacks and blues will reside at any depth in the water column.  Lings, vermillion, coppers etc...will usually be hangin on the bottom.  

IMO For halibut:

3 way swivel -

from swivel to live bait (gotta use live bait) = 24 inches of seaguar flourocarbon line
from swivel to sinker = 12 inches of 20 # mono and a loosely tied knot on a 4 ounce (depending on speed of drift) ball sinker.

*The reason why I "loosely" tie the sinker is just in case I snag the sinker on something on the bottom...I can simply give it a few tugs and loose the sinker but still keep the set-up intact (an over hand knot will do)

The Overhand Knot
The Overhand Knot or Half Knot
 

This is the simplest knot. Therefore probably the most used. The knot is very useful to support knots in yarns. The loose ends become a bit thicker. When this support makes the total bend too bulky you have to look for another bend. The overhand knot is not strong, so it is not used in situations where you might expect great force. It also reduces the strength of the rope or yarn by about 50%. But as an "anti-slip-knot" it does not have to withstand a lot.
This knot on the WEB.

    notes entered!

IMO For Rockfish:

carolina rig: use live bait, frozen anchovy or squid and simply "trooch" (slow paddle) directly on top of structure. Try to keep offering a couple of feet above structure to avoid snagging the bottom.

* I'll use 15 to 20 # mono for leader.

Thanks!

For halibut I'll use a plastic slider with 12-18" of dropper off it.  4-5' of leader to the hook, or as long as I can handle.  I like my live bait to swim around a bit in search of a butt.

-Allen

for even faster bottom bouncing, like 2-4 mph,
I have used 4 to 6 feet of dropper with an 8oz to 16oz weight (sometimes with a release)
and similar length of leader when pulling a plug (like a jointed rebel with 2 treble hooks)
around near the bottom. I use a ball bearing swivel to reduce chances of tangles.
this is good if you like to be on the move and paddling.

J