How do you keep the lures at the depth you want them to be w...

How do you keep the lures at the depth you want them to be with deep water fishing? I was aiming for about 8 feet down, and it seems to me that my lure kept on staying in shallow water.

Read the “Troller’s Bible”. There you can find out how far does your rod has to be from your lure to get a certain depth.It has to do with the lure's size and manufacturer.

Try this... http://www.acousticluretracking.com/

Hi.
Probably the best way,even though expensive to initially set up which a Charter Operator,& others I know,is a Downrigger,& Depth Sounder where you can adjust to troll at any depth you require,also they watch the setup on the Sounder,& adjusts the depth of the lures to where the Fish are.
I found when I had my boat,a 12ft Tinny,I didn't have a Sounder or a Downigger,they were just appearing on the scene,the depth depended on such things as type of Lure as some are designed to swim at different depths,speed of the boat,the Line weight was also important because lighter Line will allow the Lure to go deeper,as well as how much line was out,I still caught plenty of fish .
So you can experiment try all these things & you will also catch fish.
Good Luck as Trolling is an exciting way to fish.