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Best Intermediate Fly Fishing Line – for Slow Sinking and Better Reeling

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Top Choice
RIO: Tropical Saltwater II, WF8I/I
Airflo Sixth Sense Fast Intermediate Fly Line
Scientific Anglers Sonar Titan Full Intermediate Fly Line Wf8I
RIO Products Fly Line Tropical Saltwater Ii Wf10I/I, Clear-Tip-Trans-Green
Scientific Anglers Sonar Sink 30 Clear Tip, 200 Grain/6-7 wt Intermediate Sink - Yellow / Clear
Our Rating
4.9
4.7
4.5
4.1
3.9
Price
$89.99
Price not available
$79.95
$89.99
$89.95
Colour
Trans Green
Trans Olive, Trans Tan, Trans Green
Clear
Trans Green
Clear
Length
100 ft
105 ft
105 ft
100 ft
100 ft
Weight
WF7, WF8, WF9, WF10
WF5/6 -8/9
WF6 -WF12
WF10I/I
WF5/6 -WF10/13
Sink Rate
1.5 - 2IPS
0.5 - 1.5IPS
1.25IPS
1.5 - 2IPS
1.25IPS
Top Choice
RIO: Tropical Saltwater II, WF8I/I
Our Rating
4.9
Price
$89.99
Colour
Trans Green
Length
100 ft
Weight
WF7, WF8, WF9, WF10
Sink Rate
1.5 - 2IPS
More Information
Airflo Sixth Sense Fast Intermediate Fly Line
Our Rating
4.7
Price
Price not available
Colour
Trans Olive, Trans Tan, Trans Green
Length
105 ft
Weight
WF5/6 -8/9
Sink Rate
0.5 - 1.5IPS
More Information
Scientific Anglers Sonar Titan Full Intermediate Fly Line Wf8I
Our Rating
4.5
Price
$79.95
Colour
Clear
Length
105 ft
Weight
WF6 -WF12
Sink Rate
1.25IPS
More Information
RIO Products Fly Line Tropical Saltwater Ii Wf10I/I, Clear-Tip-Trans-Green
Our Rating
4.1
Price
$89.99
Colour
Trans Green
Length
100 ft
Weight
WF10I/I
Sink Rate
1.5 - 2IPS
More Information
Scientific Anglers Sonar Sink 30 Clear Tip, 200 Grain/6-7 wt Intermediate Sink - Yellow / Clear
Our Rating
3.9
Price
$89.95
Colour
Clear
Length
100 ft
Weight
WF5/6 -WF10/13
Sink Rate
1.25IPS
More Information

There are certain approaches to fly fishing where intermediate fly line is just unbeatable.  Intermediate fly lines are basically a sinking fly line that sinks very slowly.  

For shallow water fly fishing or fishing with a really slow retrieve, you won’t find a more helpful tool than your intermediate fly line.  

Below we offer our top intermediate fly line picks.

But which type of intermediate fly line will perform the best for your fishing needs?

Fly Fishing Atlas brings you our take on the best intermediate fly lines.

Which type of intermediate fly line will perform for your needs will depend on what type of water and which species of fish you are after.  

We offer a our top choices and explore their strengths and weaknesses.

Intermediate lines are commonly used to fish saltwater flats for bonefish.  But that’s not the only popular application.  

Intermediate lines are also super effective for fishing beaches and river outlets for striped bass and bluefish.  Nothing keeps the fly just sub-surface like a good intermediate line.

Last but not least, intermediate lines are also amazing for still water fishing.  

Regardless of whether you are after trout, salmon, or a multitude of other species, intermediate line presents your fly perfectly for fish cruising near the surface.

Before you select an intermediate line you need to know what conditions you will be expecting once you hit the water.  

Intermediate fly lines are made for freshwater, or saltwater.  

It is also very important that you select an intermediate line manufactured specifically for the range of temperatures you expect.

Intermediate lines are usually designed for warm tropical water or colder temperate water.  

You don’t want to fish with a conventional 8 weight striped bass line in very tropical water for bonefish.  

You’ll quickly find that your fly line becomes very limp and overly flexible.  The coating can even become damaged due to the softening effects of the warm water.

For top performance and the best chance of success, it is super important that you use an intermediate fly line for the correct application. 

Rio General Purpose Tropical Intermediate Fly Line

The Rio General Purpose Tropical Intermediate Fly Line is a warm water fishing line that has a hard, tropical coating. 

This makes it extremely tough which is good news when you are fishing around sharp coral and rocks. 

This line is slightly heavier than its rating, which makes it ideal for working with large saltwater flies. 

It also provides you with the fast loading that you appreciate when you’re out on the saltwater.

The Rio General Purpose Tropical Intermediate Fly lines comes in a three lines series to cover all of your saltwater bases. 

You can choose between a full floating line, a floating line with a 10-foot clear intermediate sink tip or a full intermediate sinking line with a 10 foot clear tip.

Airflo Sixth Sense Fast Intermediate Fly Line

The Airflo Sixth Sense Fast Intermediate Fly Line makes use of Airflo’s patented Delta Taper design. It delivers an extra long front taper. 

The performance result is dramatic; you will be able to cast longer with less effort, placing it just where you want in the water, without disturbing the stillness of the surface. 

The longer length of this line allows you to fish over long and medium distances. 

In addition, the rear taper is marked to provide you with a visual clue to identify the best haul zone when you’re casting.

The Airflo Sixth Sense Fast Intermediate Fly Line comes in a range of options from 5 wt to 9 wt. 

They all make use of Airflo’s PowerCore technology for positive hooksets and minimal memory.

Scientific Angler Sonar Titan Full Intermediate Fly Line

The Scientific Angler Sonar Titan Full Intermediate Fly Line is a heavy duty line that is designed to work with your biggest fishing flies. 

The intermediate density of this line allows you to keep your heaviest lines just under the surface of the water. 

The short, powerful head of this line provides you with excellent turnover.

The slow sink rate of the Scientific Angler Sonar Titan Full Intermediate Fly Line allows you to fish your flies just below the surface of the water. 

This line is ideal for temperate climates. It has a sink rate of 1.25 inches per second. 

It provides you with a braided monofilament core to provide the strength that you need when grappling with those big fish.

Rio Products Fly Line

The Rio Products Mainstream series is designed to meet the needs of the average fly fisherman. 

These lines are made to optimize the performance of your fishing rod with slightly heavier and shorter head lengths. This is an 80 foot line. 

The head length is 30 inches long with a 7 inch front taper. From there, a 25 inch body transitions into a 6 inch back taper and 42 inches of running line.

The Rio Products Mainstream series is a clear fishing line. It provides you with a sink rate of 1.5-2.0 inches per second. The 30 foot heads weighs in at 133 gr. (8.6 gm).

Scientific Angler Sonar Sink 30 Clear Tip Fly Line

The Scientific Angler Sonar Sink 30 Clear Tip Fly Line delivers a superior casting experience that is similar to the Sonar Sink 30 taper line. 

However, this line substitutes in a 30 foot slow sinking head. The clear head will ensure that you don’t spook the fish – because it won’t even see the line. 

Not only does the low viz sinking head provide you with superior casting and control ability, it also allows you to creep up on your water borne prey.

This intermediate running line is coated with an ST+ slickness additive. 

This makes that part of the line more supple so that it is more controllable, allowing you to keep that fly exactly where it needs to be to hook that fish.

The Scientific Angler Sonar Sink 30 Clear Tip Fly Line is a high durability product that has been built to be tangle free. 

It provides you with an intermediate sink rate of 1.25 inches per second. The core of this fly line is monofilament.

The Scientific Angler Sonar Sink 30 Clear Tip Fly is 100 feet in length. The running line makes up the first 70 feet of the line. 

The sink belly makes up the final 30 inches. The running line is aqua colored, while the sink belly is clear.

Available lines weights for the Scientific Angler Sonar Sink 30 Clear Tip Fly range from 200 to 400 GR, with grins rates for the first 30 feet of from 13.0g to 25.9g. 

This line is ideal for use with streamers in medium/hot weather conditions.

FAQ

Sonar Fly Line

What is an intermediate fly line?

An intermediate fly line is a line that is designed to allow you to fish just under the surface of the water. 

To allow for this, it sinks very slowly. An intermediate fly line sits in between a floating fly line and a medium sinking fly line.

Unlike most other types of fly lines, the manufacturers of intermediate fly lines often do not list the sink rate of the line. 

However, as a general guide, most intermediate fly lines will sink at a rate between one and two inches per second (IPS).

Intermediate fly lines can be differentiated into slow intermediate and fast intermediate lines. 

A slow intermediate line will have a sink rate of 0.5 to 1 foot per second. A fast rate intermediate line, will speed the sink rate up to 1.5 to 2.5 feet per second.

You can also get what is referred to as a neutral density line, which is designed to sit on the top of the water.

How and when to use it?

Intermediate lines are best used in conjunction with a fishing lure. 

They will work well single lures, weighted and unweighted lures. You can also use an intermediate line with buzzers and nymph feeders in deep waters.

There are two basic divisions of intermediate line:

  •   An intermediate line with a monofilament core
  •   An intermediate line with a braided core

Monofilament intermediate lines are thicker and are almost impossible to see when they are underwater. 

Braided core intermediate lines are usually translucent and solid in color. These two different types of intermediate line will perform differently when you are casting. 

In both cases, however, you will get a superior cast if you dip the reel in the water prior to casting.

The monofilament core will tend to get slimy when it is wet. This makes it less visible to the fish. 

However, monofilament cores tend to have more coil memory than braided cores, which can be  a problem. 

A braided core will give you better bite detection than a mono core.

How fast do intermediate line sink?

Fishing Line

The speed with which an intermediate line will sink can vary. This speed of sinking is referred to as sink rate. 

You should check the manufacturer’s specs before purchasing. 

This is not always shown on the packaging, so you might have to go to the manufacturer’s website to obtain this information.

Intermediate lines are divided into slow intermediate and fast intermediate. 

A slow intermediate line will sink at a rate of between half an inch and one inch per second. 

A fast intermediate line will sink at a rate of between one and a half and two and a half inches per second.

Conclusion

Anglers who are just dabbling in the sport of fly fishing need entry level gear. 

Even the most experienced fly anglers usually start with inexpensive fishing gear and upgrade as needed. 

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