Not all sinking fly lines sink at the same speed.
Some are designed to fish just beneath the surface, while others are capable of reaching significant depths.
The speed at which a fly line sinks is known as its **sink rate**.
Choosing the correct sink rate helps present your fly at the depth where fish are feeding. A line that sinks too slowly may never reach the fish, while one that sinks too quickly can end up fishing below them or dragging the bottom.
## How are Sink Rates Measured?
Most manufacturers describe sink rates using either **inches per second (IPS)** or a simple designation such as:
* Hover - approximately **0.5 to 1 inch per second**.
* Intermediate - approximately **1 to 2 inches per second**.
* **S3** - approximately **3 inches per second**.
* **S5** - approximately **5 inches per second**.
* **S7** - approximately **7 inches per second**.
Although exact sink rates can vary slightly between manufacturers, these designations provide a useful guide to how quickly a fly line sinks through the water.
## Hover and Intermediate Lines
Hover and intermediate lines fish just below the surface.
A hover line sinks extremely slowly, often remaining only inches beneath the surface film, while an intermediate line sinks at around **1 to 2 inches per second**.
These lines are ideal when fish are feeding just below the surface or when surface drift makes a floating line difficult to control.
They are widely used for stillwater trout, saltwater fly fishing and some salmon fishing situations.
## S3 Fly Lines
An **S3** line sinks at approximately **3 inches per second**.
It is designed to fish the upper to middle layers of the water column and is a popular choice when fish are feeding a few feet below the surface.
Many stillwater anglers find an S3 one of the most useful sinking lines for general reservoir fishing.
## S5 Fly Lines
An **S5** line sinks at approximately **5 inches per second**.
It reaches greater depths more quickly than an S3 while still allowing good control during the retrieve.
S5 lines are commonly used when trout are holding deeper during warmer weather or when fishing larger reservoirs.
## S7 Fly Lines
An **S7** line sinks at approximately **7 inches per second**.
These fast sinking lines are intended for deep water or strong currents, allowing the fly to reach fish that would otherwise be difficult to target.
They are commonly used for deep stillwater trout fishing, salmon fishing and some saltwater applications.
## Boat Fishing vs Bank Fishing
The fly lines you need will often depend on whether you fish from a boat or the bank.
Boat anglers usually have access to deeper water and can position themselves directly over fish holding well below the surface. This allows them to make full use of faster sinking lines such as S5 and S7 when conditions demand.
Bank anglers are more often fishing the shallower margins of a reservoir, where a very fast sinking line may reach the bottom too quickly or continually pick up weed and debris. As a result, many bank anglers rely more heavily on floating, hover, intermediate and S3 lines for much of their fishing.
There are, of course, exceptions. Some reservoirs have steep shelving banks where faster sinking lines can still be extremely effective from the shore.
When choosing a sink rate, think about the depth you're fishing rather than simply selecting the fastest sinking line available.
## Is Faster Always Better?
No.
One of the biggest misconceptions is that a faster sinking line will catch more fish.
In reality, the best fly line is the one that keeps your fly at the depth where the fish are feeding.
A line that sinks too quickly may spend much of the retrieve below the fish or continually snag the bottom.
Fishing at the correct depth is far more important than simply fishing as deep as possible.
## Sink Rate Depends on More Than the Fly Line
The fly line is only one part of the system.
The final fishing depth is also influenced by:
* Water depth.
* Current speed.
* Retrieve speed.
* Fly weight.
* Leader length.
* The amount of time allowed for the line to sink.
Two anglers using the same fly line can therefore fish at very different depths.
## Full Sinking Lines or Sink Tips?
Many modern fly anglers no longer rely solely on full sinking fly lines.
Salmon anglers frequently use interchangeable sink tips to alter the fishing depth without changing the entire fly line.
River trout anglers often use sinking polyleaders or VersiLeaders on floating lines to achieve a similar result.
Stillwater anglers may use either approach depending on the fishing situation.
Each system has its advantages, and the best choice depends on the type of fishing being undertaken.
## Which Sink Rate Should I Buy?
If you're new to sinking fly lines, there's rarely a need to buy the fastest model available.
Choose the sink rate that matches the depth you expect to fish most often.
Many experienced anglers gradually build a selection of different densities, allowing them to cover changing conditions throughout the season.
## Related Articles
* Floating vs Intermediate vs Sinking Fly Lines.
* Integrated Fly Lines vs Shooting Heads.
* Choosing a Fly Line.
* Salmon Fly Lines.
* Stillwater Fly Lines.
## Peaks Fly Fishing Tips
* Think about the depth the fish are feeding before choosing your sink rate.
* An S3 sinks at around 3 inches per second, an S5 at around 5 inches per second and an S7 at around 7 inches per second.
* Faster sinking lines are not automatically better.
* Boat anglers often benefit from carrying faster sinking lines than bank anglers because they can access deeper water.
* Building a small selection of line densities will cover far more situations than relying on a single sinking line.
