G
~ I have never used a depth finder....one just tries a variety of baits at different depths and keep on paddling around (trolling) until you catch one...this has worked for me for over 30 years ~Do you use a debt finder? The guys I went to Quetico with did and it was a big help in them finding the fish in a new lake.
Me, I don't use one and never did catch a lake trout there.
I caught a huge smallmouth though, but they said it's a long ride from the east coast to Quetico to catch smallmouth....