Rip charts is one of the better ones but you do have to pay for it!! Fish track is a good source for an sst and is free for other stuff like currents tho you will need to pay!! You should be looking for big breaks in tempreature is a first sign to look for where the cursor is is where I would start to look then if you know any fad marks in the vicinity of these breaks that's where I'd be heading!!! Hope this helps even a little!!