We used the smart troll system for these findings using
shallow diving lure
50’ of 15# leader
18# leadcore
20# backer line
2.5mph down speed
3oz snap weight
before we always hooked our snap weights to our backer line right where the leadcore connection was and found it would take us about 37’ down
when we hooked the same setup with the snap weight at the leader/leadcore connection we would be about 43’ down.
if we hooked the snap weight at the second color of lead(on the leadcore itself) it would be about 50’ down
numbers are close to what I remember but may be slightly off