Sinking Line Setup For Deep-Water Smallmouth

As the season progresses and warm weather settles in, big smallmouths often move to deep water to find cooler temperatures and different food sources. This is when the topwater bite fades and a floating line just won't cut it. To consistently catch fish during these periods, you need to get your fly down into their world. That means understanding what sinking line setup works best for deep-water smallmouth.
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Why is a Sinking Fly Line Essential for Smallmouth Bass Fishing?

During the post-spawn period of early summer and the hot days of late summer, smallmouth bass in larger rivers often retreat to depths of 10 to 20 feet or more. They hang out in deep pools, along submerged ledges, and at the bottom of channels where the water is cooler.

Here’s why a sinking line is a better tool for the job:

1. Maintains Depth: A sinking line gets your fly down and keeps it in the strike zone throughout the retrieve.
2. Better Connection: It creates a more direct line between your fly rod and the fly, allowing for better strike detection and hook sets.
3. Casting Big Flies: Sinking lines are built with aggressive tapers designed for throwing big flies and making long casts, which is often necessary in bigger rivers.

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Floating Line vs. Sink Tip Fly Line

A floating line is best for much of the smallmouth season, especially when fishing in the spring season, when fish are in shallow water. It’s perfect for poppers and for fishing streamers in depths less than six feet.

But once the fish go deep, a floating line struggles. Even with weighted flies, the buoyant line pulls the fly up in the water column during the retrieve. This means your fly spends less time where the fish are.

The result? You’ll catch the same fish in the upper water column, but you’ll miss the big ones holding deep. A sinking line solves this problem by keeping your fly at the desired depth.

The Main Types of Sinking Lines for Smallmouth Bass

When it comes to getting a fly down, you have a few options. Each has its own strengths depending on the situation.

1. Full Sink Lines

A full sinking line setup for smallmouth bass does exactly what its name implies: the entire length of the line sinks. These lines are categorized by their sink rate, typically measured in inches per second (ips).

For smallmouth bass fishing, a line with a sink rate of 3-6 ips is a great all-around choice.
1. When to Use It: Full sink lines are ideal for fishing deep waters or the deepest pools in big rivers from a boat. They excel when you need to make long casts and let your fly get down deep before starting your retrieve.
2. Advantages: They provide the most direct connection to your fly at depth, making it easier to feel a subtle bite. They are also the best tool for consistently keeping a fly at a specific depth in the water column over a long distance.
3.Considerations: Mending is impossible with a full sink line. Casting can also be a bit more challenging, as you have to lift the entire sunken line out of the water to recast.

What is the Best Fishing Line for Smallmouth Bass

2. Sink Tip Line

A sink tip line is a hybrid, featuring a floating running line and a sinking section at the front (the "tip"). The tip length of the rod can vary from just a few feet to 30 feet or more. For smallmouth rivers, a 10- to 24-foot sink tip is a versatile choice. It allows you to mend the floating portion of the line to control your fly's drift, which is crucial for presenting a fly naturally in moving water.

The ability to mend the floating line gives you more control over your presentation. It’s easier to cast than a full sink line because you’re not lifting as much sunken line from the water. Heavy sink tips can create a "hinge" effect during casting if your timing is off. The floating portion can also get pulled down in very fast or deep currents.
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3. Intermediate Line

An intermediate line is technically a sinking line, but it has a very slow sink rate, usually around 1-2 ips. It’s designed to sink just below the surface.

An intermediate line is perfect for fishing just under the surface in water on windy days or for retrieving streamers in the top few feet of the water column in a river. It helps get your fly below surface chop and keeps spooky fish from seeing your fly line.

It's great for a slow, controlled retrieve with a lighter fly when fish are suspended. It’s not a tool to get into deep water. It’s a specialty line for specific situations.

What About Poly Leaders?

Poly leaders (or sinking leaders) are a budget-friendly way to turn your floating line into a sink tip. These are tapered leaders with a coated core that allows them to sink at various rates. You attach one to the end of your floating fly line, then add a short tippet.

Poly leaders are a fine option if you only occasionally need to fish deep. But, they are not a true substitute for a dedicated sink tip fly line. They can be clunky to cast, and they don’t have the power to turn over big flies as effectively as an integrated sink tip line.
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Choosing the Right Fly Fishing Gear

For most smallmouth bass fishing with a sinking line, a 7- or 8-weight fly rod is the sweet spot. This gives you the power to cast big flies and heavy sink tips, and it has the backbone to fight a big river smallmouth in heavy current.

Pair your rod with a quality reel that has a smooth drag. While you don’t need a high-end trout reel, a good drag is important when a big bass makes a strong run. Here are some other fly fishing gears you will need.
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What is the Best Rig for Smallmouth Bass

Final Thoughts

So, what sinking line setup is best? For an angler fishing smallmouth rivers from a boat, a versatile sink tip line with a 15- to 24-foot tip and a sink rate of 3-5 ips is tough to beat. It offers the perfect blend of depth control and line management for river currents.

Being able to switch from a floating line to a sink tip on the water can be the difference between a slow day and good fishing. The next time the summer heat pushes those smallmouths deep, you’ll be ready to follow them.
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What Sinking Line Setup Works Best for Deep-Water Smallmouth?