Generally, sinking lines are more difficult to cast than floating lines. That’s not a big surprise now when we know they must be heavy upfront to sink, and they can kick like a mule.

Why are the Sinking lines difficult to cast?

Remember they are not designed to be cast easily – they are designed to sink and cast big heavy flies – to catch fish floating lines can’t reach.

These lines kick because the leader can’t bleed away the surplus energy in the fly line’s end see this blog.

So, the real issue is the transition from the line tip to the leader. It is difficult to impossible to match the mass of the leader’s butt to the mass of the line tip. The line tip may be very small but quite heavy due to its density – remember it’s designed to sink. To match the masses the leader´s butt would have to be considerably thicker than the fly line’s end.

Correctly designed lines will have a mass profile that doesn’t change when going from the floating to the fast-sinking sections of a sink tip line. The floating part is huge, the sinking part is small, but the mass/inch is the same. Badly designed sinking tips lines will in addition have the clunky uneven mass transition.


Two errors

Usually, fly slingers make two errors when they cast and rig sinking lines.

The line. The first error relates to the cast. Understandably, casters try to cast the sinking line as they would cast a floating line, and that does not work very well. Cast a line like that straight back it will stop and bounce and create slack. Because of the kick, with each cast, control of the line is lost, and it compounds (remedy below). Remember the big and heavy fly usually used in tandem with a sinker is waiting for its opportunity to strike the back of the caster’s skull – ears are a good target too. So, false casting should be minimized and can be downright dangerous. 

The leader. The second error relates to the leader. The butt of the leader anglers use is frequently way too thin, so the transfer of energy will not be optimal creating more bounce. To use a suboptimal leader is an unforced error. Sometimes your casting abilities are evolving but the effort of tying on a suboptimal leader is the same as tying on an optimal one. So, pay attention to your damn leader’s butt.

Since the issue with sinking lines is at the transition to the leaders only, there isn’t a need for long leaders, at least not to cure casting ills. The leaders need to be long enough to temper the kick somewhat, but no longer. When the line kicks so does the leader, of course. The part of the leader’s butt forward from the fly line, helps to temper that kick, usually 2-3 ft. of butt is enough. There are diminishing returns going longer than that. Then add a taper and tippet and a total leader length of 4-6 ft. works well for casting, and the short leader also gets the fly down quicker than a longer leader would do. 

Here is a useful blog on the same

https://www.demystifly.com/post/2017/04/20/tips-to-help-you-cast-and-turn-over-big-flies


How to cast a sinking line

The solution. Forget nice sharp loops these lines can’t be controlled casting that way. Open your loop to minimize the kick. Make one back cast and then briefly lay the line down in front of you. Pick that line up and make another back cast, shooting line to get the line’s head out of the tip-top, then shoot the front cast. No false casting is required. Lay down every fore-cast once the head is out of the tip-top and shoot the next fore-cast. This is much safer and easier to do than trying to false cast a with a dense head and a big heavy fly. A Belgian or an oval cast works very well, especially with an on-shoulder wind. As you retrieve your line and get ready for the next cast, the line is now in the water, not on the water as the floater is. It is not possible to go into a backcast with the line sunken like that. You might even break your rod if you tried. The solution is to make a roll cast or two and get the line to the surface. Once there we can make our usual pick-up. Remember to pinch down the barb for your own sake if not for the fish’s, just in case.

Here is a video of the Belgian cast.

https://www.thecampflyfishingschool.com/pages/belgium-cast

Line management of a sinker. Fishing in water the stripped sinking line will sink if not managed. Obviously, the line does not come as easily from the water as a floating line comes off the water. The stripped line can be coiled and held in the stripping hand, or a stripping basket can be used.

Rod. Casting sinking lines isn’t about short distance and accuracy, it’s all about distance and covering a lot of water. Therefore, soft rods (noodles) aren’t appropriate. In the right hands they can work, of course, but why fight a slow rod when a faster one would work better? Beginners and intermediate casters would be well advised to use fast rods for casting sinkers.


This picture has nothing to do with sinkers but just begged to be posted.

Snæfellsjökull
Snæfellsjökull

All fly casters have experienced a fly line “kick.” So, what is this kick? The fly line kicks when the tip part suddenly accelerates at the end of a cast and careens about (like a whip does). The reason behind the kick is that there is undissipated energy left in the loop when it straightens. That energy must go somewhere and the end of the fly line kicks thus dissipating energy. When casting floating lines, the kick is mostly a casting error (too much power), but it can also be used to the caster’s advantage (more later). Lines, where the mass of its head is pushed forward, are prone to kicking whether it is a sinking tip or a floating tip. The mass upfront is the issue, not the line’s density per se. When casting a line with a heavy sinking tip it will kick to a varying degree. Let’s break it down into various components.

The leader

Any line, cast without a leader, will kick no matter how gentle the cast. Just go ahead and try for yourself. There should be, by necessity, a little bit of energy left in the fly line to turn over the leader and the fly. (Now it is also obvious why you need more force to turn over a fly as it gets heavier). The leader is designed to dissipate the rest of the energy and still have enough to turn over the fly. Now you immediately realize that the leader must be constructed in such a way as to be able to do this. Imagine a scenario where you put a 6X 3.7lbs tippet on a 15# flyline (Diameter 0.005’’, 0.13mm). You intuitively realize that’s never going to work. Mass moves mass is the mantra (see blogs below). And the reason is that the mass of the leader’s butt is just too small to accept the excess energy. The mass of the leader’s butt is predicated by the diameter of the butt (not the break strength).

https://everyjonahhasawhale.com/blog/your-butt-is-too-small/

The caster

When I cast a floating line, I like to spend just enough energy to turn the ensemble over and lay it out straight in front of me. However, I can make any line kick by just using more force. Now, this is a casting flaw unless you want the line to curve at the cast’s end. There are two named casts where we use excessive force to curve the line. First, we have the Tuck cast where we cast in the vertical plane and overpower the cast, and the line and leader tuck down, and we can make the fly land first on the surface. This is used for instance when you want the fly to sink fast as in nymphing.

https://troutbitten.com/2019/04/16/fly-fishing-strategies-the-tuck-cast/

https://www.sexyloops.com/flycast/tuck-cast/

The other is the Curve cast where we cast in the horizontal plane and curve the line around an obstacle for instance a stone in the water. This is possible to do when casting in the horizontal plane. The trick is to overpower the cast and the line curves either to the right with a horizontal left-sided cast or left using a horizontal right-sided cast.

https://flyfishingthesierra.com/curve.htm

https://www.sexyloops.com/flycast/overpowered-curve-cast/

It is the same principle and the same cast. The tuck cast is in the vertical plane and the curve cast is in the horizontal plane.

The line’s design

Line with mass pushed forward
Line with mass pushed forward

Now undissipated energy can be there because of the line’s construction. All lines where the mass is pushed forward will certainly kick more than most other line designs. Sinking tips will kick more because of their mass (not density), but floating lines like the one above will also kick. But that’s OK, these lines are designed to cast bigger flies AND for the sinkers, the tip must sink fast so there is lots of mass in the front. But we don’t care, we’re not throwing dry flies. Good for big/heavy flies. If the tip casts smoothly it does not sink well and thus fishes badly. If the tip sinks well and fishes well it is harder to cast. You must pick your poison!

Sinking lines and sink tips are made by incorporating small pieces of tungsten (from Swedish – literally heavy stone) into the PVC coating. This increases the density of that part of the line. The tips are furthermore thinner than the floating head part and that fact is responsible for the decreased drag and the speed-up of a line thus constructed.

https://everyjonahhasawhale.com/blog/sinking-lines/

For the savants

The line kick can be much more subtle. One of my friends when rigging a new 2-3 wt. line cuts off the factory welded loop and attaches the leader with a 2-turn needle knot. He feels the welded loop “kick” just a bit and doesn’t like that. Line/leader attachments often result in a little lump of mass right where we don’t want it. But with the right leader butt and attachment method, the transition from line to leader can be made very smooth.

Technical consultant: Bruce Richards