There are five primary trolling techniques: Flatline, weighted, weighted line, diving planer and downrigger. With the exception of flatline trolling, each technique involves the use of a specific type of equipment or accessory designed to place the lure at the correct depth, with the desired action, and at the proper distance from the boat.
Flatlining is the simplest, most basic and popular trolling method. It involves pulling a lure or baited hook(s) with conventional, unweighted fishing line (usually monofilament or braided nylon) with no additional terminal tackle between the main line, leader and lure. The only equipment necessary to flatline troll is a rod, reel, line and lure, making it accessible to any angler with access to a boat and salt water.
When flatline trolling, the depth the lure or bait can reach is entirely dependent upon its weight, shape and design, as well as the speed at which the boat is traveling. Due to these factors, trolled lures or bait may only reach a maximum of 30 feet deep, often much less. Yet flatlining is often used in very deep water to present lures at or just below the surface, where deeper dwelling game fish will come up to investigate. Due to its effectiveness in shallow depths, flatlining is also popular for inshore trolling.
Flatline trolling frequently requires a long line to reach areas that are revisited by fish after the boat passes. It may often be necessary to troll 200 to 300 feet of line or more behind the boat. In addition, because many of fish will be at each side of the boat, maneuvering in an s-shaped pattern may improve the odds of putting the lure within the strike zone of the fish.
Perhaps the most challenging aspect of flatline trolling is ensuring that the bait or lure runs at the proper depth. Because there is no added weight to the line, lure or bait, each is more susceptible to wind, current or wave action. These factors can all affect lure depth, speed and performance. Knowing what depth the lure will attain at various boat speeds, line length, current and wind strengths is fundamental to trolling success. Much of this knowledge comes from experience and practice.
Keeping a lure or baited hook(s) at the proper depth often requires attaching some sort of weight to the line, which allows a lure to sink faster and travel deeper than it could go with unweighted, flatline trolling. Weights and sinkers come in many shapes and sizes egg, drail, split shot, keel, bell, barrel, bead chain, walking sinker and others and most are made from lead or other heavy metal.
While the use of weights on a line definitely takes the lure or bait deeper, actual trolling depth is still influenced by boat speed, current and wind. Trolling with a weight attached to the line differs little from flatlining because there is a limit to how heavy a weight can actually be attached to a line and still have the line be manageable. This can limit the depth to which the line can be dropped and also hinder lure action. To troll in depths of 30 feet or more, most anglers employ weighted lines, diving planers or downriggers.
Trolling with weighted fishing line is similar to flatline trolling or trolling with weights attached, but depth control is achieved through weight that is built directly into the line, causing the line itself to sink. Lead-core line, which consists of lead filament encased in a nylon shell, is one example. Wire line, either a single strand of metal wire or a combination of strands braided into one, is another popular weighted line. In both cases, depth can be controlled by how much line is let out.
The primary benefit of weighted line over line with weight attached is that the weight distribution is more even and the behavior of the line is more predictable. Also, many weighted lines are color-coded or marked at various lengths to indicate how much line is out, which helps the angler estimate the depth at which the bait or lure is running.
There are, however, some drawbacks to weighted lines. Despite their sinking ability, they too are susceptible to drag, wind, current and boat speed. They also demand heavier tackle than conventional fishing line. Wire line can develop kinks that may compromise line strength and manageability. And because of their density and lack of stretch, weighted lines can diminish the fight when a fish is hooked.
Diving planers allow anglers to troll deep water without attaching excessive weight or using weighted line. These disk-shaped devices can be attached directly to conventional fishing line, and their unique shape produces resistance when pulled through the water, causing a diving action that pulls the lure or bait behind it. Similar to using weighted lines, the depth that the lure will run behind the planer is determined by how much line is let out.
When a fish strikes a lure trolled behind a planer, the line will disengage from the planer, allowing line to pass through with little or no resistance. However, the planer remains attached to the line, which can hinder fish-fighting ability.
Most planers (often referred to as planer boards) can be adjusted to swim to the side of the boat, and many anglers employ multiple planers to cover different depths and distances from the boat. Moderately heavy tackle and line are required to handle the strong resistance produced by planers, even if the bait or lure is relatively light.
A downrigger is the most effective tool for precise, controlled-depth trolling at virtually any depth. A downrigger set-up consists of a strong base mounted to the boat transom (or other location near the back of a boat), onto which a spool of heavy cable is attached. The cable is placed through the downrigger arm with a pulley system and descends straight down into the water below the boat. Heavy weights, often called cannon balls, are frequently attached to the cable to anchor it at a precise depth, determined by how much cable is released from the spool. Some downriggers can accommodate up to six individual lines, which gives anglers the ability to spread lures over a variety of depths, angles and distances.
To troll with a downrigger, the fishing line and lure are attached to the downrigger cable via a small clip (or release). Once attached to the cable, the line and lure are taken down to the desired depth for trolling. Once a fish strikes the lure, the line is jarred free from the clip, allowing the angler to fight the fish directly.
Most saltwater trollers consider sonar to be essential equipment when downrigging. Sonar helps determine the depth at which the lure should be presented by identifying the depth at which fish are located. Some also attach temperature or speed gauges to the downrigger cable to monitor these important factors to fishing success.