Complete Guide to Sinking Fly Lines

When the fish are down, the fish are down, and oftentimes, there’s only one way to consistently produce bites–a sinking fly line. While weighted flies and longer leaders will get your fly down into the column, there are countless scenarios in which a sinking line is the only tool for the job. When it comes to punching through swift stream current or tidal flow, reaching the depths in still water fisheries, or simply dredging the bottom and staying there, you’ll want a few sinking setups in your quiver. Our guide to sinking fly lines will help you to determine which type of intermediate, sink tip, or full sinking line to wield and when, as well as some on the water tactics and general food for thought on the topic.

Sinking Fly Line Overview: What, Where, When

While fish may rise for a dry fly or hit a popper, a majority of fish live and feed deep in the water column. I’ve experienced countless days of fishing where the difference between a few taps and getting consistently crushed has simply been a matter of fishing the fly a foot or two deeper. Alternatively, sometimes all of the action is far deeper than you can reach with a floating line, so there’s just no way to find the bite without a sinking setup. Whether you’re trying to keep your streamer a few feet into the column for the duration of your retrieve or need to drop your fly into the depths, there’s a sinking setup for the job.  

What:

The main characteristic of a sinking fly line, when compared to a floating fly line, is its density. Sinking lines are built with materials that are heavier/denser than water, enabling them to sink into the column rather than ride on top. The coating on sinking fly lines is also designed to cut through the water rather than create buoyancy–similar to how fluorocarbon sinks more rapidly/willingly than monofilament. There are weight-forward tapered sinking lines and level-sink rate sinking lines without any taper, so this characteristic varies depending on what type of sinking setup you go with. Higher surface area also hampers the ability of a line to sink, so sinking lines are narrower than floating lines. The rate at which a fly line sinks is typically measured in inches per second or IPS. 

Where:

Where exactly are sinking fly lines best/most effectively utilized? Simply put, wherever there are fish that you can’t reach with a floating line. Sinking setups are the ticket for fish that are glued to the bottom, holding on deep structure. They’re also pivotal for punching through fast currents when the fish are deeper, and a floating line just doesn’t have the oomph to get you down there–even if “there” is just a few feet deep. A sinking or intermediate line can also be your best friend in open-water saltwater fisheries where you want your fly to stay beneath the wave chop. Stillwater fishing a pond or lake may also call for a sinking line if your target species is known to cruise and/or feed somewhere deeper in the water column.

When:

There can certainly be some seasonality surrounding sinking lines. It’s important to think about fish behavior, bait presence/absence, stream flows, water clarity, and much more throughout any given fishing season.

In many trout fisheries, for example, fall streamer fishing can be red hot. When the fish are keyed in on baitfish rather than hatching bugs or the lower flows encourage them to hold in deeper features of the stream, the best way to deliver your fly into the juiciest zones will almost undoubtedly be a sinking line. 

On the tidal flats of my native Cape Cod, there are often several day or week periods of the summer when the sand eel presence is prolific, and the striped bass focus their feeding efforts on sucking them off of the bottom substrate. I’m sure to equip a sinking line when I notice an abundance of sand eels, green crabs, glass shrimp, or other bait species that dwell on the bottom.

Sometimes, day-to-day conditions can determine whether or not you need a sinking line. For example, when shore fishing against a strong headwind, the added weight and loading power of an intermediate or slow sinking line can be helpful in punching through the wind for longer distance casting. The narrower line is also inherently more aerodynamic, so it slices through wind resistance better than floating lines with wide-diameter bellies. Fishing larger streamer patterns on sinking lines can also be a great go-to tactic after heavy rainfall in the event stream or lake conditions become turbid, and the fish are less inclined to seek out smaller bugs in the lower visibility. 

Different Types of Sinking Fly Lines:

Sinking fly lines range from intermediate to full sink and are available in several other configurations depending on the scenario you are fishing. Determining what line is right for the scenario you are fishing will maximize your time on the water and draw more strikes.

Intermediate Lines 

Benefits:

• Significantly more pleasant to cast than sink tip and full sink setups
• Not such an aggressive sink rate that you can still fish a buoyant popper, slider, or floating pattern if the bite unexpectedly turns topwater

Drawbacks: 

• Will not fall nearly as deep into the water column as more aggressive sink rate lines

Intermediate lines cast and behave similarly to floating lines while also offering a bit of sink (typically 1-2 IPS) in order to get your fly deeper into the water column. They are the most versatile sinking line because you can both fish streamers close to the surface if quickly retrieved or unweighted and decently sub-surface if you give your fly line some time to sink. If you’re struggling to deliver your fly just a few feet (or even inches) deep due to current, choppy surface conditions or wave wash, perk your ears here. Particularly buoyant flies like bulky deer hair patterns, for example, can also be fished just subsurface if that’s the zone you want to stay in rather than stripping the fly top-water.

As an avid striped bass angler here on my native Cape Cod, I find myself gravitating towards an intermediate line for most days of fishing. An intermediate setup allows me to keep my unweighted and/or stubbornly buoyant streamer patterns just beneath the chop for better presentations while also allowing me to count down weighted flies fairly deep into the column (tidal current permitting). While casting for false albacore, stripping the fly FAST is essential – an intermediate line allows me to vigorously double-hand strip patterns right on the surface without pulling the streamer out of the water. 

Sink Tips

Benefits:

• Typically more pleasant to cast than full sinking setups – especially when a tapered shooting head is employed.
• Running line will not sink into the water, making for easier line pick-up and casting without use of a stripping basket.
• Can manipulate your floating running line in order to make mends and alter fly direction and sinking duration.

Drawbacks: 

• Won’t deliver the fly as deep into the column as full sink lines in most scenarios
• Will create more vertical scope or hinge effect in your retrieve due to the floating running line, which may or may not be desired. Keep in mind this effect also dampens your connection to your fly.

Sink tips consist of a floating running line and a sinking tip section that’s usually all of or most of the shooting head. The sinking tip section varies in length depending on the fly line but typically measures around 10 feet. There are shorter and longer options that are purpose-built for certain tactics/applications. Some options have nice tapered shooting heads, while some simply consist of a level sink rate. By utilizing a floating running line (and sometimes part of the shooting head as well), sink tips offer better casting and mending control than full sinking lines and even some intermediate options. 

Sink tips are oftentimes the best tool for the job in scenarios in which you need to get the fly down quickly but not necessarily terribly deep. For example, targeting holding trout in the bottom of a deep pool or tucked up under a cut bank with swift current will require an aggressive sink rate–but if the stream is only six or seven feet deep, a 10-foot sink tip with a fast sink rate will likely get you down there just as well as a full sinking line. 

Here’s where the advantage really lies when utilizing a sink tip vs. a full sink option–better line control and management. Sink tips are usually more accurate and pleasant to cast due to them mostly consisting of a floating line, so if you want the best balance between easy and accurate casting and the ability to fish deep, this is the go-to. Also, keep in mind that the line you have stripped out to cast won’t sink into the water down to your feet. Even a longer 15-foot sink tip section should be off of the water with just one false cast so you can avoid the frustrating challenge of pulling your line out of the water while casting. This is especially handy when fishing streams and moving water conditions.

Another advantage of sink tips is the ability to mend your (floating) running line when compared to full sinking options. You can throw a big upstream mend or shake out some line in front of you to keep your line from swinging so soon, giving your sinking tip a bit more time to get deeper into the column. The ability to employ this tactic may very well prove to actually get you deeper into swift currents than a full sinking line can due to the increased line control. 

Full Sinking Lines

Benefits:

• A full sinking line with an aggressive sink rate is typically the best way to fish as deep into the water column as possible. Level sink rate lines will punch deeper than varying sink rate lines.
• Better feel and more direct connection to your fly than sink tips due to decreased hinge effect in your retrieve path.

Drawbacks:

• Significantly more strenuous and technical to cast than intermediate lines and most sink tips.
• Sinking running line means you very well may need a stripping basket in order to effectively pull your line off the water and up into your cast.
• More aggressive sink rates will not allow you to fish on or near the surface if you need to change your program in a pinch

Full sinking lines have no floating line segments anywhere in the taper or running line, so the entire fly line sinks. There are full sinking lines that consist of a single, level sink rate, and there are options that offer a varying sink rate with several different sink rates from the shooting head to the running line. In most contexts, anglers trying to present the fly as deep into the water column as possible will want to employ a full sinking line option.

Single or level sink rate lines will give you the most aggressive sink rate, dropping your fly into the zone quickly and keeping it there the longest. If you’re trying to fish DEEP, a level full sinking line with an aggressive sink rate is your best option (think type 6 and 7). These style full sinking lines also keep your fly at the desired depth for the longest retrieve duration when compared to varying full sink lines. This detail makes this style of full sinking line great for fishing difficult to punch through fast-moving currents like you’ll encounter on big rivers.

Varying sink rate lines are a bit more friendly to cast because they employ several different sink rates and are usually tapered like traditional floating lines. In this regard, they offer better line control than level sink rate options. These lines have the most aggressive sink rate at the tip of the shooting head and then transition to a slightly slower sink rate towards the middle/back of the head, and then oftentimes transition to an even slower sink rate at the running line. A full sinking line that goes from 6 IPS at the front of the head to 4 IPS at the rear of the head and then down to 2 IPS at the running line offers much more control than a level full sinking line.

This varying sink rate also creates a straighter diagonal line path to your fly when compared to single/level rate sinking lines, therefore offering a more intimate feel and connection to the fly. I’ve found that full sinking options that employ a varying sink rate are particularly stellar for still water applications because they offer a better connection to the fly while also descending just fine when unimpeded by current.

Polyleaders

Benefits:

• Super quick and easy way to turn any fly line into a sink tip of your desired sink rate.
• Pack as compact as a store-bought leader, so you can stash a whole array of polyleaders in your pocket!
• Priced much more affordably than a new fly line.

Drawbacks:

• Even if designed with a nice taper, many polyleaders will have an undesired hinge effect at the connection to your fly line while casting.
• Will create more vertical scope or hinge effect in your retrieve (depending on your fly line)
• Oftentimes have lower long term integrity than fly lines.

Polyleaders are an entire topic of their own we could really get into. A polyleader is, as the name implies, a leader system that you can attach to the end of your fly line with a simple loop-to-loop connection. Like fly lines, polyleaders are offered in floating, intermediate, and sinking options. They can be a wonderfully quick and easy way to add some sink into the equation that enables you to utilize a floating line if that’s what you’re rigged up with. Similar to sink tips, polyleaders vary in length for different fishing applications, typically 5-15 feet long. They can also be designed with a taper in order to make the polyleader feel more like an extension of the forward taper of your fly line.

I utilize a 7-foot intermediate polyleader setup (by Airflo) paired with a floating fly line while fishing the tropics, and I absolutely love the way it fishes. The 1.5 IPS polyleader sinks at about the same rate as my fluorocarbon leader material, so I think of it as more of a user-friendly leader extension than a tool for getting my fly down. I simply attach 3 to 6 or so feet of fluoro to the end of the polyleader with a loop-to-loop connection, and I’m ready to fish. I burn through way less butt section leader material when utilizing this setup, and I love the stiffness and abrasion resistance of the line coating. I was at first skeptical about the casting dynamics and leader presentation due to the loop-to-loop connection in the middle of my leader setup, but I’ve found it doesn’t hamper my loops while casting nor negatively affect my connection to the fly. That being said, I have fished with polyleaders that have a dreadful hinge effect and are, therefore, not very pleasant to cast. The greater the difference in sink rate between your fly line and your polyleader, the greater the potential hinge effect will be. 

Setting Up a Sink Tip Rod/Reel Setup

Now that we know the differences between the various types of sinking lines, we can start to spin our wheels on building the ideal sinking setup. The most relevant and practical questions to ask yourself while getting geared up with a new sinking setup are, in my opinion, as follows. How deep do I want to present the fly? How much of a factor is stream current/tidal flow in the fishery I’m targeting? What sort of prey item(s) am I attempting to imitate, and how does it naturally behave? What are my line management needs/preferences while actively casting? The best sinking line setup will be the one that satisfies the most criteria for your specific angling contexts, so make a checklist and go with the line option with the most check marks.

First and foremost, keep in mind that sinking fly lines are much more of a chore to cast than floating lines–especially when you get into high IPS options with sinking running lines. That being said, carefully consider just how aggressive of a sinking setup the fishery you’re targeting really requires. 

Also, remember that swift currents will impede intermediate and low IPS rate sinking lines from properly descending into the column–so consider this detail perhaps above all others. Trying to reach that large and in charge trout holding at the bottom of a deep and fast pool? You’ll want an aggressive sinking setup. Struggling to get your big and bulky deceiver or deer hair patterns deep into the surf and/or tidal flow? You guessed it–a high IPS, no-nonsense sinking line.

If the fish are substantially down in the column but you’re casting into still water, you might not necessarily need to go with a heavy-handed high IPS option. Even slower-rate sinking lines at 2 or 3 IPS will get down deep into the zone as long as your fly line isn’t scoped or swung by the current. Simply “count down” to your desired depth before starting your retrieve. A lot of anglers get turned off of sinking lines because of how tricky and strenuous they can be to cast, especially in contexts where you’re blind casting all day and putting your wrist and casting arm through a lot of strain. If the conditions allow your fly line to descend unbothered by current – do yourself a favor and go with a less aggressive, full sinking option, it’ll get down there with a little patience. 

You might be used to over-weighting your floating lines on certain rod setups in order to create more loading power. As we’ve discussed, these fly lines are far heavier than traditional weight-forward floating lines, so we suggest fighting the urge to over-weight your sinking setup. In fact, I’ve found that some full sinking lines I’ve fished have already felt a bit overweighted after purchasing for my exact rod weight, so be mindful of this. Many full sinking lines are offered in different grain weights rather than corresponding to rod weights, so be sure to carefully consult the recommended rod pairing for each option, and don’t push the limits of your rod too far. Faster action rods will usually handle the upper end of the spectrum better, so if for example you’re thinking about buying a 350-grain option that’s recommended for 9/10 weight rods, a stiff 9wt or any action 10wt will likely pair better with that line than a softer 9wt. 

Certainly not to be overlooked – remember certain action and model fly rods make for better streamer rods and sinking setups than others. Typically, a medium or fast action rod will be your friend for delivering heavy flies and fly lines, so if you own exclusively soft rods, you’re probably going to want to get yourself a new stick with some proper backbone. This factor goes double when you get into higher weight rods and bigger, bulkier flies. 

Your reel option is probably the least important factor to consider when building out a new sinking setup. The one detail that may be worth thinking about is that sinking lines have narrower diameters than floating lines with wider shooting heads. This narrower line diameter might give you a bit of extra room for a higher backing capacity, so if you’re purchasing a new spool for an existing trusty reel, perhaps you can hold more backing than you’re used to.

Unfortunately, there is likely not one sinking line that’s going to hit all the bases required for your target fishery or species. This means that experimenting with a few different sink rates and types of sinking lines is worth your time and fishing funds in order to determine which sort of setup(s) will be best for the different contexts in which you fish.

Final Thoughts 

Sinking fly lines are a valuable tool for anglers looking to extend their fishing opportunities into new areas and seasons. Just like floating fly lines, different lines work better for different scenarios. As the first piece of a two-part series, this guide to sinking fly lines gives you the tools needed to find the right sinking line for your desired fishery, as well as the tools needed to properly get everything prepared for the water. Stay tuned as part 2 dives into how to properly fish the appropriate sinking lines for a variety of fisheries.

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