Fishing wet flies downstream and across is a traditional and effective technique for catching trout and grayling on UK rivers.
The method involves casting a wet fly across the river, or diagonally downstream, and allowing the current to carry it across the flow under controlled tension.
This movement is known as the wet fly swing.
As the fly moves across the current, it can suggest an aquatic insect swimming, drifting or emerging towards the surface.
Unlike upstream wet fly fishing, where the angler generally attempts to follow the natural drift, downstream and across fishing deliberately uses the current to create movement.
The key to successful downstream wet fly fishing is controlling the speed of the swing rather than simply allowing the current to pull the fly across the river.
How to Fish a Wet Fly Downstream and Across
The basic technique is straightforward.
- Position yourself where you can cover likely feeding water without disturbing the fish.
- Cast the wet fly across the river or diagonally downstream.
- Allow the fly to sink briefly if necessary.
- Maintain contact as the current begins to carry the fly across the river.
- Control the line so the fly swings through the water at a suitable speed.
- Allow the fly to complete its swing before retrieving and casting again.
The current provides most of the movement.
There is usually no need to retrieve the fly continuously.
However, small adjustments to the fly line and rod position can make a considerable difference to the presentation.
Understanding the Wet Fly Swing
When a wet fly is cast across a river, the current acts on both the fly and the fly line.
As the line comes under tension, the fly begins to move across the current towards the angler's bank.
The precise path depends on the casting angle, current speed, line position and amount of tension.
At the beginning of the swing, the fly may travel downstream while gradually moving across the current.
As the line tightens, the fly can accelerate and begin to rise through the water.
Towards the end of the swing, the artificial may hang almost directly downstream.
Trout and grayling can take at any point during this movement.
The angler should therefore remain attentive throughout the entire presentation.
Why Does the Swing Work?
Aquatic insects do not always drift passively downstream.
Some insects swim, struggle or move towards the surface during emergence.
A wet fly moving across the current can suggest this behaviour.
The movement may also encourage a fish to intercept the artificial as it passes through its feeding area.
However, a wet fly swinging rapidly across the river may move much faster than the natural insects.
This can reduce the likelihood of a take, particularly when fish are feeding selectively.
The objective is to create controlled, believable movement.
Choosing the Right Casting Angle
Casting angle has a major influence on how the wet fly behaves.
Casting Directly Across the River
A cast made approximately 90 degrees to the current often creates a relatively pronounced swing.
The current catches the line and begins moving the fly across the flow.
This can be useful when covering water, but the angler may need to control the line to prevent the artificial accelerating too quickly.
Casting Diagonally Downstream
Casting at approximately 45 degrees downstream generally creates a more controlled presentation with less immediate sideways movement.
This is a useful starting point for anglers learning the technique.
The fly can be allowed to travel through the current before completing its swing downstream.
Casting More Directly Downstream
A cast directed farther downstream creates a different presentation.
The fly may travel under tension with relatively little sideways movement.
This can be useful when fishing a particular current seam or narrow channel.
However, the fly may remain under tension throughout much of the presentation, so careful control is important.
Small changes in casting angle can significantly affect the speed, depth and movement of a wet fly.
How to Control the Speed of the Swing
One of the most common mistakes in downstream wet fly fishing is allowing the fly to swing too quickly.
This often happens when the fly line lies across a faster current than the water containing the artificial.
The faster water pulls on the line, causing the fly to accelerate.
There are several ways to control this.
Change the Casting Angle
A more downstream casting angle may reduce the speed at which the fly moves across the current.
Experiment with different angles until the presentation suits the water.
Mend the Fly Line
A mend involves repositioning part of the fly line after casting.
An upstream mend can reduce or delay the pull of faster water on the line, helping the fly drift farther downstream before swinging.
A downstream mend can increase tension or encourage the fly to swing sooner.
The effect depends on the arrangement of currents.
The important thing is to understand how the line influences the artificial.
Adjust the Rod Position
Moving the rod tip can alter the tension and direction of the fly line.
Raising the rod may reduce the amount of line resting on the water.
Moving the rod sideways can influence the angle of the swing.
These movements should be controlled rather than exaggerated.
Control the Amount of Line
Long casts can make downstream wet fly fishing more difficult, especially on rivers with several different currents.
Fishing at a manageable distance usually provides better control.
A shorter line can also make it easier to detect takes and maintain the correct presentation.
Should You Mend the Line When Fishing Wet Flies?
Yes, when necessary.
Mending is an important part of controlling wet fly presentation.
For example, imagine casting across a river where the water between you and the fly is moving faster than the water containing the fish.
Without adjustment, the faster current may pull the line downstream and drag the wet fly across the feeding area too quickly.
An upstream mend can help delay this movement.
This gives the fly more time to travel through the intended area before the line tightens.
However, excessive mending can disturb the water or move the fly unnaturally.
It is generally better to make a controlled adjustment early in the presentation rather than repeatedly moving the line.
Not every cast requires a mend.
If the fly is travelling at an appropriate speed, leave it alone.
How Deep Should the Wet Fly Fish?
The depth of the artificial is influenced by the current, casting angle and amount of tension.
A wet fly that is immediately pulled across the river may remain relatively shallow.
Allowing the fly to sink briefly before the line tightens can help it reach a greater depth.
An upstream mend may also provide additional sinking time by delaying the swing.
However, traditional lightly dressed wet flies are generally most suited to fishing the upper and middle layers of the water.
If trout or grayling are feeding close to the riverbed in deep or fast water, weighted nymphs may be a more effective choice.
The aim is to present the wet fly at a depth where feeding fish are likely to encounter it.
Where Should You Fish Wet Flies Downstream and Across?
The technique is particularly useful where the current can carry the artificial through several likely feeding positions.
Riffles and Runs
Riffles and runs often contain large quantities of drifting aquatic insects.
Trout and grayling may hold behind submerged stones or in slightly slower water, intercepting food carried by the current.
A controlled wet fly swing can be effective through these areas.
Avoid allowing the fly to race across faster water.
Current Seams
A current seam is the boundary between water moving at different speeds.
These areas can concentrate drifting food and provide convenient feeding positions.
Fish may hold on the slower side of the seam while intercepting insects passing through the faster current.
Try to arrange the cast so the wet fly passes through the seam without being pulled away too quickly.
Pool Heads
The head of a pool is where incoming water begins to deepen and spread.
Food is frequently carried into these areas by the main current.
A wet fly can be presented across the incoming flow and allowed to swing through likely feeding positions.
Pool Tails
Pool tails can be productive because the current narrows and accelerates as water leaves the pool.
Fish may hold in the deeper water immediately above the shallower outflow.
Wet flies can be swung through these areas, although careful presentation is important in clear or shallow conditions.
Water Beside Rocks and Boulders
Rocks create areas of slower current where trout and grayling may hold while feeding.
A wet fly passing along the edge of these sheltered positions can be effective.
However, it is important to control the swing so the artificial travels through the feeding area rather than being pulled rapidly away from it.
How to Cover a River Systematically
Downstream wet fly fishing is particularly useful for searching water when fish are not visibly rising.
Rather than casting repeatedly to the same position, work through the available water in an organised way.
Begin with a manageable cast across or diagonally downstream.
Allow the fly to complete its swing.
On the next cast, extend slightly farther across the river or alter the casting angle to cover a different line of water.
Once you have covered the water within reach, take a few steps downstream and repeat the process.
This allows you to work through a run or pool without repeatedly fishing the same area.
Avoid Walking Into Unfished Water
One of the disadvantages of downstream fishing is that the angler is moving in the same direction as the current.
Fish holding downstream may be disturbed if you wade too quickly or approach too closely.
Before stepping forward, consider whether fish might be lying immediately below your position.
Keep movements slow and deliberate.
Whenever possible, fish the nearer water before attempting longer casts.
There is little benefit in casting to the far bank if doing so disturbs fish that could have been caught closer to you.
Why Do Trout Take at the End of the Swing?
The end of the swing can be particularly productive.
As the fly approaches a position directly downstream, its sideways movement slows.
Depending on the current and line tension, the artificial may rise or hang beneath the surface.
This change in movement can suggest an insect approaching the surface during emergence.
Trout sometimes intercept the fly at this point.
For this reason, avoid lifting the fly immediately after it finishes swinging across the river.
Allow it to remain in the current briefly before retrieving.
A gentle lift or short retrieve may sometimes encourage a take.
However, avoid repeatedly pulling the fly sharply towards the surface without a reason.
How Do You Detect Takes?
One advantage of downstream and across wet fly fishing is that the line is often under tension.
This means takes can be easier to feel than when fishing upstream with a relatively slack line.
A take may feel like:
- A sudden pull.
- A sharp tap.
- A gradual tightening of the line.
- A heavy resistance.
- A series of small knocks.
Sometimes the fish takes the fly and turns away, creating a distinct pull through the rod.
At other times, particularly when fish are feeding gently, the take may be much more subtle.
Remain attentive throughout the swing, including the final moments when the fly is hanging downstream.
Should You Strike When a Fish Takes?
A common mistake is to strike aggressively when a trout takes a wet fly under tension.
Because the fly line is already relatively tight, a forceful strike can pull the hook away from the fish or break the tippet.
In many situations, the fish will hook itself against the tension of the line.
When you feel a take, allow the rod to absorb the initial movement.
A controlled lift or gentle tightening is usually sufficient to establish contact.
If the fish is already pulling strongly, avoid adding unnecessary force.
This is particularly important when fishing with small hooks or fine tippet.
Why Are You Getting Takes Without Hooking Fish?
Missing takes is a common frustration when fishing wet flies downstream.
There are several possible causes.
Striking Too Quickly
A sharp strike against an already tight line may pull the fly away before the fish is properly hooked.
Try maintaining contact and allowing the rod to absorb the take.
Excessive Line Tension
If the fly is moving rapidly across the current, trout may make brief or unsuccessful attempts to intercept it.
Slowing the swing can sometimes improve the number of fish hooked.
Blunt or Damaged Hooks
Check the hook point regularly, particularly after snagging the riverbed or striking a rock.
Fish Taking the Fly Tentatively
Sometimes trout investigate or nip at an artificial without taking it properly.
Changing the presentation, fly size or pattern may improve the response.
Not every pull or tap represents a fish taking the fly securely.
Fishing One Wet Fly or a Team
Downstream and across fishing can be practised with a single wet fly or a team of two or three.
A single fly is easier to control and is a good starting point for beginners.
Fishing a team allows several patterns to be presented simultaneously.
However, a team creates additional resistance in the water, and the flies may behave differently depending on their position along the leader.
A team also requires more care when casting, particularly in windy conditions or confined spaces.
Start with a simple arrangement and concentrate on controlling the swing.
More flies do not automatically produce a better presentation.
When Is Downstream and Across Fishing Most Effective?
The technique can be useful throughout the trout and grayling fishing seasons, subject to local regulations.
It is particularly effective when:
- Fish are feeding on insects beneath the surface.
- Emerging insects are moving upwards through the water.
- There is sufficient current to create a controlled swing.
- Fish are not visibly rising.
- You want to search a run or pool systematically.
It may be less suitable in extremely shallow, clear water where fish are easily disturbed.
Very fast or deep water can also make traditional lightly dressed wet flies difficult to present at the required depth.
As with any fly fishing method, the conditions should determine the approach.
Common Downstream Wet Fly Fishing Mistakes
The most common problems include:
- Allowing the fly to swing too quickly.
- Casting too far and losing control of the line.
- Failing to adjust the casting angle for different currents.
- Allowing faster water to drag the fly away from the intended feeding area.
- Mending excessively and disturbing the presentation.
- Retrieving the fly before it has completed the swing.
- Striking aggressively when a fish takes under tension.
- Wading downstream too quickly and disturbing fish.
- Repeatedly casting to the same water rather than covering it systematically.
- Concentrating on the middle of the swing while ignoring the beginning and end.
Most of these problems can be corrected by shortening the line, adjusting the casting angle and paying closer attention to the movement of the artificial.
Key Takeaways
- Downstream and across wet fly fishing uses the current to move the artificial across the river.
- The movement is known as the wet fly swing.
- Casting angle influences the speed, direction and depth of the fly.
- A diagonal downstream cast is a useful starting point.
- The fly should move through the water under controlled tension rather than racing across the current.
- Upstream mends can delay the swing and allow the fly more time to sink.
- Current seams, riffles, runs and pool heads are productive areas to explore.
- Fish the near water before extending your casts farther across the river.
- Cover runs and pools systematically by adjusting casts and moving downstream carefully.
- Takes can occur at any point during the swing, including when the fly hangs directly downstream.
- Avoid aggressive strikes when fishing under tension.
- A single wet fly is an excellent starting point before progressing to teams.
Successful downstream wet fly fishing is about controlling the current's influence on the artificial.
By adjusting the casting angle, managing line tension and carefully covering likely feeding areas, you can present traditional wet flies effectively to trout and grayling throughout a wide range of UK river conditions.
In the next article, we'll look at Upstream Wet Fly Fishing, including the traditional North Country spider method, controlling the drift and detecting subtle takes.
