On big water, 10- to 12-weight rods are ideal because you will be casting large flies for long periods — sometimes in high wind — and there are big fish in big water. You want to land that fish safely. With a 10- to 12-weight rod, you have plenty of backbone to control larger fish and land them in a safe amount of time.
If you are fishing water six feet or deeper, there is no need for intermediate lines. Using sinking lines/heads will make casting all day much easier. I like to match a 400-grain line with a 10-weight rod and 450- to 550-grain line with a 12-weight rod. For a leader, I use about 18 inches of 50- to 60-pound test fluorocarbon or monofilament from the fly line tied to about 15 inches of 40-pound test flexible wire. I don’t like to use fluorocarbon tied directly to the fly because of the risk of bite-offs, but if you insist on using fluorocarbon I highly suggest using 100-pound test or heavier.
Next let’s talk about fly selection. Movement and color are two highly-important characteristics of flies. If I had to pick one that is probably more important I would it is fly movement over color. Since current is less of a factor in lakes, the fly’s design has to be on point.
I prefer a fly that glides back and forth with each strip (similar to a glide bait). That’s not to say a fly that rides straight or dives up or down won’t have its day; it’s just that I think flies that glide get more action from