Of the different types of sinking line the very slow sinker is the most versatile. It can be used to over come a cross wind prblem, or to fish a nymph or lure in the upper layers of water, or over weedbeds and underwater snags.
To locate the depth of water trout are feeding use the countdown proccess. Cast out and count 10 seconds. Then 15 seconds. Then 20 seconds and so on untill trout are located then continue to fish that depth.
Although the very slow sinking line is versaitile it would not be practical to use exclusively, as it would take far to long to sink to fish who are lying well down in extremely deep water. When searching for fish in these places use a fast or very fast sinking line.
When retrieving a lure, especially quickly, it is important to hold the rod correctly in relation to the line. Some trout will take a lure in a very savage manner. It is therefore best to hold the rod at an angle to the line, in order to cushion the shock of a taking trout.