Please check out our new for 2017, XD camera housing technology and “Live Strike” trolling system for greater trolling capabilities.
http://help.aquavu.com/knowledge-base/xd-camera-housing/
For older systems, trolling effectively depends on depth and also on the length of cable you have out which determines water resistance or “drag.” The deeper you go, with more cable out, the more drag there will be. That requires slower travel for good viewing. Generally, for optimal viewing, we recommend going less than 2 miles per hour. Remember, the slower you go, the more detail you will see. Also, the faster the bottom depth changes, the more rapidly you will need to manipulate the Aqua-Vu cable.