Most of the better trolled add either 1 or 2oz snap on sinker 20ft behind crank then more line till get your desired depth.The total line out from crank to board on dive chart is depth of lure,then add 4ft/1oz to that to get depth of lure.That is a good starting point on depth.Another consideration,especially during this early spring is when trolling very slow,the weight pulls the crank even deeper.Had dive chart of 1.0,1.5 and 2.0mph and you get a lot deeper at that 1.0mph speed.A lot of variables on where your lures are running.That is why you want to cover the water column initially with your lines before you find depth fish are active.