So I fish a lake thats 30 feet deep for crappie and I am using a Lowrance Elite 4x for ice fishing, has a LCD screen and does a good job of detecting even small fish down to 30 feet bottom. But it wont detect my crappie jig any lower than 10 feet and its hard to tell at what depth my jig is sitting at and I waste a lot of time trying to get my jig at the right depth in the water column.  Is a Vexlar or Marcum sensitive enough to solve this issue?