Trolling Depth & Line Length

Use Your Boat’s Wake to Judge Trolling Distance

In a trolling spread, you will likely have between 4 and 8 lines out of various lengths and depths. The idea behind a trolling spread is to create a group of lures and baits to imitate of school of baitfish. Each line can have a single lure, or something like a spreader or daisy chain of lures. Anglers new to trolling are often unsure of how far back the lure pattern should be. A good rule of thumb is to keep lures close enough to stay in the boat’s wake, but not so close that the turbulent water prevents the lure from working properly. You’ll have more success if you keep the spread between 50 and 200 ft of the boat because the wake creates an attractive commotion. In this article, you’ll learn how to estimate the best distance and depth for different types of lures and baits.

Several lines are out when trolling to maximize the coverage of the area. Some lines are shorter, and some are longer. Some are deeper and some are shallower. While these lines are out, the boat captain is driving the boat in S curves near structure to entice fish to strike.  Imagine what longer lines would do during a turn. They could very easily collapse into each other and get tangled. It takes a very skilled captain to prevent long lines from tangling.

As the boat is making its S curve patterns, the speed of the lures also change. The speed of a lure on a long line on the outside of the curve will go significantly faster than a lure on the inside of the turn with a short line. This can unintentionally change the action of your lures to a point where it’s no longer working properly.

When trying to find the right amount of line to let out, consider the captain’s input. If its overly difficult for the captain to maintain the spread while turning back and forth, it may be time to reel in some of the line. Tangled lines have the potential to ruin a day of trolling. Shorter lines are far less likely to run into each other during turns.

On the flip side, if you’re too close to the boat, you risk placing your lure in a spot that’ll spook the fish. There is a sweet spot where the wake attracts them and the boat doesn’t scare them and that sweet spot varies by boat and speed. To see if you’re too close to the boat, look at your lures and see if they're behaving properly.

If you know you’re traveling at the right speed for your lure, but the skirted lure with a concave head is staying submerged instead of bubbling up to the surface periodically, it’s probably drowning in the prop wash. Trolling too close to the boat could also prevent a diving lure from swimming straight.

How to Repeat a Successful Trolling Setup

Once you find the appropriate range of distance behind your boat, likely between 25 feet and 175 feet, you’ll want to be able to replicate it. When you hook into a fish and reel it in, someone will be reeling in the other lines to clear them and you’ll want to put them all back out and repeat the successful set up after the fish is retrieved. There are several options to help replicate the distance. One is a line counter which is a very precise method, and another is timing.

For line counters, you can either buy a reel with a line counter on it, or buy a line counter and mount it to your rod. You can find conventional reels with line counters, like the Abu Garcia Ambassadeur Line Counter Reels. Electric conventional reels, like the Hooker Electric Penn International has a built in line counters, level wind and electric retrieve. This can be tremendously useful when trolling or bottom fishing very deep waters.

Line counters are not used very often. The reels with them attached are often not the best reels or they’re too heavy for most trolling applications. It's far more common for fishermen count or use a stopwatch to measure how long the lure was leaving the spool. Long lines are usually let out in freespool for about 30 seconds and short lines will be let out for about 10-15 seconds. Of course, this can vary with the speed of the boat and the type of lure. A diving lure will be traveling diagonally, out and down, whereas a flatline will just be traveling out. You’ll need to consider this when setting up your spread.

Test Your Tackle to Estimate Trolling Depth

Trolling is a difficult technique to master for several reasons. It can feel like you’re putting so many lines out to figure out what will work. And then once you get bit, replicating it is difficult because so many variables must be recreated the same way. The boat speed, the sharpness of the turns, the depth of the lure or bait, and the distance behind the boat. Boat speed is relatively easy to duplicate, but how can you possibly know how deep you were trolling?

Anglers can take an experimental approach by tracking the depth in which a lure, bait, or planer, hits bottom at various speeds. Another method is using the information supplied with the lure to estimate the depth. Hands-on experience is often what gives anglers a gut feel for trolling depth.

Keep reading to learn about the different methods of lowering lures and baits to depth, and how to estimate the depths.

Achieve Depth with Downriggers, Planers, Crankbaits & Leads

There are a variety of ways to get bait and lures deeper when trolling. Planers, trolling leads, downriggers, and crankbaits are frequently used. Downriggers are typically required to reach depths of 50 feet or more. Downriggers are mounted to the boat transom. A trolling weight is attached to the downrigger with a strong cable and connected to the fishing line with a release clip. The downrigger can descend to the target depth and easily releases the fishing line when a fish strikes.

Planers are bulky and heavy, but very effective at gaining depth. They are connected to the fishing line with a snap that gets released when its reeled in close to the boat. When planers are “set”, they dive and hold the line down. When a strike occurs, the planer “trips” and releases pressure allowing you to reel it in as you fight the fish. The planer is cleared from the line once it reaches the boat.

Planers require lots of rigging with the bridle, wind on leader, and snap swivels. Some anglers prefer not to use planers for this reason. Crankbaits are the simplest way to gain depth, although they can be susceptible to damage. The crankbait is connected to the topshot or leader and the lure dives in the water. There is no extra hardware to release or remove while a fish is brought to the boat.

Crankbaits can be used in high speed trolling applications, but they must be in great condition to work properly. Any imperfection in the diving lip, or chip in the body, or misaligned eyelet will affect how the lure actions and how deep it dives. When using crankbaits, always inspect them before use.

Professionals will take the time to document how deep their diving lures go at different speeds. You can do this on a special trip in shallower waters (30 feet or less). Set out your lures, record the boat speed and record the depth when the crankbait hits bottom. Do this for all of your lures at a variety of speeds and you'll know exactly what lure to put out the next time you see fish about 15 feet down when trolling.

Trolling leads can also be used for depth. These are rigged inline with a leader and lure following it. The downside of a trolling lead is that you cannot clear it from your line. You will likely keep your leader short because you’ll have to stop the retrieve when the lead gets to the rod.

When planer trolling with a trolling rod, you’ll likely trolling at about 5-6 knots and using a size 3 planer or smaller. Larger planers put so much pressure that they require the use of a dedicated trolling rod or rigging up to a cleat on your boat. I wrote an article about trolling rod and reel combos, check it out here.

Planers run at about a 45 degree angle which means for every 10 feet of line you have out, you’ll get about 5 feet of depth. The planers can reach a point where the water pressure at depth prevents it from going any deeper.

The table below shows comparable options for getting approximate trolling depths.

Desired Depth (ft)	Lure	Planer
< 10 ft	DTX Minnow 145 Shallow	Clarkspoon # 1
10-15 ft	X-Rap Magnum (4-3/4” body)	Clarkspoon # 2
15-30 ft	DTX Minnow 140 FLT	Clarkspoon # 3

Your fishing line can also affect the depth achieved. Braid has a small diameter and can slice through water easier than mono of the same line strength. However, usually when braid is  used as the mainline, its used with a long monofilament topshot. If your topshot is so long that the braid doesn’t get in the water, you’re effectively trolling with monofilament from a depth perspective. Read more about Trolling Topshots and Leaders in my article, here.

When you find fish and they’re deeper than your spread, you can try different techniques to raise the fish to your lures. Fishermen will often chum the waters, or toss out some live baits to gain the interest of the fish below.

Each Lane in Your Spread Needs Different Amounts of Line

The amount of line let out from the reel for a troll depends on the distance behind the boat and the depth of the bait or lure. Much more line is required to get to 50 feet of depth with a downrigger, than to get a surface lure just behind the prop wash. Trolling spreads have several lines at various depths and distances from the boat. Because of this, the amount of line anglers should let out for a troll varies greatly. A surface lure in the center of the spread is likely close to the boat and only requires about 25-30 feet of line let out. A spoon lowered with a downrigger for a long bottom line may require hundreds of feet. Read more below to learn how to estimate how much line to let out for a troll.

Each part of your trolling spread will require a different amount of line to be let out. As an example, let’s say you have 5 lines out, we’ll call them line A, B, C, D, and E. Lines A and E are on the outsides and are long lines, say 75 yards back, with suspending crankbaits targeting a depth of about 15 feet. Lines B and D are teasers with bait strips on downriggers at a depth of 30 feet and a distance of about 50 yards. Line C is a surface trolling lure just beyond the prop wash, about 25 feet away from the boat.

Using this example, you can see how each “lane” in your trolling spread requires a different amount of line to be let out. Most anglers don’t carry a line counter to measure the distance, so they’ll estimate by counting. If a deeper depth or a further distance from the boat is desired, you’ll need to let out more line. A good starting point is letting out about 15 seconds worth of line. From there, you can adjust a little more or a little less.

The amount of line needed for trolling is commonly thought about when choosing a trolling reel size. It can be hard for an angler new to offshore trolling to imagine the need for 1000 yards of line on a size 50 reel. The amount of line on your reel must account for the line you let out for the troll and plenty of spare line for a running fish. Wahoo are known to run for a couple hundred yards before anglers can really start fighting them.

Now you should have a better idea about lure and bait depth and placement in a trolling spread. Before you leave, read my article on the Best Tuna Lures (and Bait!) for Trolling, Casting, and Jigging. Tight Lines, y’all!