You will need a good fish finder, and some way to spot lock or anchor.
On days with no or little wind or current, you can drift. But those days are typically reserved for early morning and you don't get too many of them out in laker territory.
A helix 7 will do the job, but the bigger, the better. The reason for this is that every single pixel on a find fisher matters when hunting lakers. You need to read their every move. If they sneeze, you want to know immediately. Because once you see them start to run, you want to start reeling up and away from them.
I use a helix 12, and that seems just about perfect. At the front of my boat, I have a helix 10, and that seems a bit small and much harder to read than the 12. If I had no fish finders and had to buy them all over again, I'd go as big as possible for lakers because every data point matters.
Here's my video on showing you how to set up a Helix Humminbird Fish Finder. You should get an idea from this. This is on a Helix 12.
https://youtu.be/b8O5UoM4o0sIf I had a Helix 7 and no spot lock, I'd certainly get a trolling motor with spot lock before looking to upgrade my Helix 7. You can work with the Helix 7 because you can have it focus in on the 40 feet off the bottom, the part that matters. If you are in 120 feet of water, set your upper range to 70 or 80, and your lower range to 130. Yes, you want your lower range deeper than the max depth because you want to be able to see every pixel on that bottom. You do not want the bottom to ever go off the bottom of the screen. This is critical.
If you have any questions, let me know. If you are interested in whitefish and lakers, be sure to subscribe to my channel as I'll be putting out a lot of great content that's going to help you for next spring/summer. I'm fishing them literally every day possible during the soft water season.