You guys who use trolling weights or even line counter reels... I have a question.

Here's my situation. I am using 2 oz weights to troll crankbaits. I become confused as where I start counting the line I have out to be at fish level. If I want to fish at 15 ft do I (a) include only the amount of line under water (b) include all line past the reel (c) only the line between the weight and surface the surface. This question is driving me absolutely nuts trying to do it correctly. I am catching fish but it might be by accident