Steel wire is the most traditional and the absolute worst way to fish deep for Lake Trout. You need a tuna rod, steel wire and a huge bait-casting reel or one of those reels that looks like your grandmother's clothes-line wheel. Steel Wire fishing is responsible for Lake Trout not being a popular fish because this method is not enjoyable and has many disadvantages. Getting soar arms and a soar back from yanking the wire all day is not enjoyable. Having no idea how deep you thus rarely catching fish also makes this method very un-enjoyable. Most people try it once and never fish for Lake Trout again but some people love it and still fish this way.
Dipsy Divers are small and fit in your tack box. They get your line down deep and when the fish hits your lure, the clips release so you are bringing in the fish free-line and can feel the fish fighting. The downfall of Dipsy Divers is it's hard to know how deep you are so they are only effective in late spring when the Lake Trout are in a transitional period and found all over at multiple depths. With Dipsy Divers there is so much drag on your line while you are trolling, you have to use heavier line and a heavier fishing rod. With Dipsy Divers, when the diver hits bottom, so does your lure thus you lose more lures on snags. The Diver itself can scare fish away. It's much better than steel wire and more fun to use than downriggers and you can troll in rough weather but it's not the best way.
In larger boats that can't troll slowly you have to use downriggers. Downriggers are great at quickly getting you down to the exact depth, which is important because Lake Trout are all located in a narrow band of 53 degree water in the summer. You can also use any lure you want. They also have the advantage that if you do get a fish on there is no weight on the line. Downriggers are also a great way to fish deep in rough weather. There are disadvantages:
1) You can't feel the Lake Trout bite and you can't set the hook normally, which is half the fun. The fish either stays on the line or it does not stay on. You miss a lot of fish that strike because you can't set the hook right away.
2) You have a big steel ball screaming through the water and the Lake Trout tend to swim off to the side and away from the path of the lure.
3) In a big boat with multiple lines you can't stop the boat so you just horse the trout in and don't feel the fight or strength of the fish.
4) If you do have downriggers on a small boat you can stop the boat and enjoy the full fight of the fish but you have to reel up all the steel balls and lines so that the Lake Trout does not get all tangled. Then you have to put all the balls and lines down again.
5) Downriggers are expensive, not easily mobile and you have to drill holes in your boat to mount them. If you are flying into remote northern lakes you can't bring downriggers with you.
Bait Walkers work. They fit in your tackle box and you can troll as deep as 70 feet with a 2 oz. They are inexpensive and in small lakes you can troll right along the bottom and quickly reel in or lower you line deeper. A big downfall is your lure is only a couple of inches above the sinker so you tend to get a lot more snags. You also have a big weight between the lure and your fishing rod. As a result, there is a lot more stress on the line between the lure and the sinker and the line can break from setting the hook or fighting the fish, especially if the Lake Trout starts rolling. The weight also takes away some of the fight, which is especially true with smaller tout. This is an effective way of Lake Trout fishing but not the best way.
If you know the lake well and know where the trout are located then jigging is a very effective method. Lake Trout do not like scented rubbers but they do like salted rubbers. The twister tails you would use for Walleye are not effective. You should try to find rubbers shaped like minnows, leeches or Crayfish (Crawdads). Jigs with rubbers do not work nearly as well as the feathered Marabou Jigs. The feathered Marabou Jigs, depending on the color, can closely mimic natural insects. Adding a tiny piece of worm, minnow or salt-cured minnow works great. If you do not know the lake well and don't know of any areas where there is a dense congregation of Lake Trout; it's best to troll around and find them before you try jigging.
3-Way Swivel Trolling Rig
If you are in a small boat with a 25hp motor or smaller or you are in a big boat with a small kicker motor or electric motor then the very best way to fish deep for Lake Trout is with a 3-way swivel rig. The only disadvantage to the 3-way swivel rig is it's hard to fish in rough weather because boat-speed is a very important factor. Generally Lake Trout don't feed as well in rough weather anyways.
All you need is your Walleye or Pike fishing rod with 6 or 8-pound test line. With a 2-oz. weight you can easily troll 50 to 70 feet deep. You will need 3-way swivels, a 2-oz. weight, some regular swivels and a light flutter lure like a MooseLook Spoon, William's Wabbler, Nasty Boyz Spoon or something thin and light. The very best Lake Trout lure is the Sutton Silver Spoon but they are very hard to find. You will need to get your local bait store to order them if they can find someone who has them. There are many light weight flutter spoons on the market.
Get two 2.5-foot pieces of line and tie a normal clip-swivel to the end of each line. Then tie the other ends to different eyes on the 3-way swivel. Then clip a 2-oz. weight on one end and clip a light flutter lure to the other. Then have a clip-swivel on the line that's attached to your fishing rod so you can take the rig off-&-on easily.