Knowing depth without downriggers

[BearLakeFishGuy]

here is a chart using 12 lb line at 1.2 mph which is a good speed for this time of year .    

This is going to be dependent on the lure you are trolling too.  If you're using a 1/2 oz crankbait with a big lip, you can add another 20-30' to the depth of the lure.  Same thing with a flatfish versus a rapala.  I think these are more designed for spoons or dodgers with a squid.  Still helpful though.