Clawman, I think that the best answer to your question is that there really is no definitive answer. The problem is that the question (what leader size?) is too vague and there are too many variables. What dodger are you using? What lure are you using? How stiff is the leader you are using? You can ask 100 different anglers this question (leader size?) and you will likely get 1000 different answers. Here is how I choose to break it down. Consider your most important variables first. These would include (but aren't limited to) dodger size/style, leader strength/material and lure size/style. The way that I approach the issue is to keep some of the variables constant. This means that I do the following:
Some anglers use stiffer leaders for hootchies and flies that don't have any action of their own and softer leaders for spinners and the like. I always use the same leader material and I prefer to use a 15# flourocarbon.
Keep your lure size constant. I will admit that some of my lures are larger than others, but most of them are relatively the same size.
Here comes the controversial part. I keep almost ALL of my leaders the same length, regardless of what is tied on the end of it. As I stated in "the article" that was referenced in another thread, I tie ALL my leaders to 13.5". If I feel that a certain lure does not have enough action, I change the size or style of my dodger. So, if I'm using a 4/0 dodger and feel that I'm just not getting enough action, I will change my dodger to a 3/0 or a tear-drop/wobbler type. Still not enough action? Throw a 2/0 on there. I have personally found that a 2/0 or a larger tear-drop/wobbler type dodger with 13.5" of 15# flouro leader will almost always give me more than enough action. Conversely, if I feel that I am getting too much action on my lure, I will simply go to a smaller dodger. Using this approach will involve having many different sizes of the same color/pattern dodger.
If you still feel like you aren't getting the type of action that you want, there are a few other options. The first would be to have a few different leader rolls that are pre-tied up. For example, one leader roll would have the most action (10") and another would have less action (11" or 12") and yet another would have the least (13"-15"). This way you could keep a constant size on your dodger and lure style/size, but vary the length of the leader. You could also have different rolls that are tied with different leader strengths (i.e. one roll with 8# leader, one roll with 10# etc). Everything is pre-tied so you could experiment with it all to find just the right amount of action. The final way to do it would be to have all your leaders extra long (24" or so) and then cut and tie a loop on the spot to where you think you have the most action. The problem with this is that after you cut and tie a few on the water, it may be a little bit of a pain to keep track of exactly how long you tied each one and keep things consistent.
The easiest answer to the question of leader size is this:
How much action do you want on your lure. If you know how much action you want, it will be a lot easier to decide how long your leader needs to be. The absolute best thing you can do is hold your dodger/lure combo next to the boat at whatever speed you will be trolling at. Start with a known leader length (say, 13.5" is a decent place to start IMO) and then adjust from there. It will take some experimenting, but you will eventually get a feel for how much leader length will be needed on different lures to get the action you desire.
One more point that I really need to stress. Even though you may get 5 answers regarding leader length, has anyone ever told you EXACTLY WHERE THEY ARE MEASURING? I measure all my leaders from the bottom bend on the trailer hook all the way to the top of my loop (double surgeon loop that attaches to the dodger). Some anglers my be measuring from the eye of the top hook and others that will measure from the top of the lure. So, when I say I go 13.5" with my method (bottom of trailer to top of loop), that would mean that it would translate to roughly 10"-11" with another method (eye of top hook to top of loop). It could also mean that the same lure could be measured at 8"-10" if measured from the top of the lure (think where the clevis/blade is). You could have 3 guys looking at the exact same pre-tied lure and get three different ways to measure the leader length.
Hope that is enough to get you started for now. I hope that all of this has helped in some way and not just given you way too much to think about. If you have any more questions, feel free to ask.
