When you go after really big fish, you want Cortland’s C16 backing on your fly reel.

For routine applications, most any decent backing will do. Bluegills and brookies just don’t have the horsepower to really test your tackle. But that’s not true for all species, with tarpon and permit being obvious examples. For demands of that sort, there are alternatives to be considered.

Generally speaking, the most popular backings are made of Dacron, which features two essential attributes. It has little stretch, meaning it’s unlikely to compress and warp your reel spool, and it resists rot. Dacron is also affordable. You can buy 100 yards of 20-pound Cortland Micron, which has set the standard for quality for more than 50 years, for only $11.95.

Dacron’s limitation is that it is old technology, and newer lines offer the better strength-to-diameter ratio that trophy anglers want. The material used for making those lines is high molecular weight polyethylene, or HMWPE.

Is HMWPE significantly stronger?

Let’s compare Micron to Cortland Gelspun, which is made of HMWPE. Twenty-pound Micron has a diameter of 0.017 inches, which is excellent for a Dacron line. But it’s not even close when compared to the Gelspun. At 0.016 inches, the Gelspun has a breaking strength of 65 pounds.

That’s a huge difference.

The Gelspun and its kin are not without their limitations. Like all HMWPE lines, these lines are very slick, much slicker than Dacron, and that means you should be meticulous with your knots. The pronounced strength of HMWPE, however, helps in that even a 50 percent knot would still be darn good when you’re using a 65-pound line.

(A corollary to the issue of knot slippage is that HMWPE lines will also slip on your reel arbor under pressure if you don’t take precautions. One solution is to wrap the arbor with a three or four wraps of Teflon plumber’s tape before spooling up the backing. You can also use masking tape, but that will leave a residue on your spool. Some anglers prefer to put down a base of Dacron or monofilament, but I recommend against the mono because of the compression issue.)

What if you can’t afford knot failure?

Let’s begin by accepting that some level of weakness is inherent in most any knot. You can sort of get around the problem by using a Bimini twist, which is as much braid as knot. But Biminis are bulky, and they can begin unraveling when passing through your rod guides.

What if you could eliminate the knot? You can do that with C16.

Most HMWPE lines are “solid” braids, meaning they are woven together like a girl’s pigtail, with no space between the braids.

C16 is different in that the strands are woven together like a straw, with an open core surrounded by an outer wall. This “hollow” braid can be spliced, eliminating the need for knots.

What do I mean by splicing?

An obvious splice is the blind splice loop, which lets you loop the backing to your fly line. Here’s a video link showing how it’s done:

Note that the fellow in that video uses a piece of wire in place of a splicing needle, and wire works well with heavier lines. I’ve even used a loop of stiff nylon monofilament when wire wasn’t available. But when you’re working with small-diameter lines, specifically designed splicing needles are helpful. I have a set of Daho needles, with seven threading needles rated from 50-pound to 200-pound; small, medium and large loop splicing needles; and a medium reverse-latch needle. That gives me the ability to splice everything I’ve attempted so far.

Splicing will also allow you to rig a fly line directly into your hollow C16 backing. Here’s a video link:

This splice definitely looks cool; it is also incredibly strong. Most important in my view is the fact that it’s perfectly smooth, so you never have to worry about knots bumping through your rod guides when fighting a really hot fish.

Now, some will complain that a fly line-to-backing splice is awkward should you ever break off and have to rig up on the water. I don’t really see the problem, because carrying the necessary needle in your gear shouldn’t be that difficult, but let’s not argue the point. You can always do an emergency rig using standard knots.

A third technique is the in-line splice, which lets you connect two hollow braids without knots. Check out this video:

When would you use an in-line splice?

Imagine your reel needs 300 yards of backing, but you only have two spools of 150 yards each. If you’re using solid braids, you can knot the lines together, except now you have the same problems you always get with knots. With C16, splicing creates a perfectly smooth connection with full strength. In short, you’ve eliminated wasted line without having to rely on knots.

Being able to splice remnant spools is of special interest to retailers or anyone else who buys bulk spools. If a 3,500-yard spool gets down to 175 yards, for example, it’s no longer necessary to throw that remnant away. Just splice it to the next spool.

Another way of using an in-line splice is to add a warning strip to your backing. Go back to my example of putting 300 yards of backing on your reel. Start with 150 yards of chartreuse C16, and finish with 150 yards of blue. Now, when your hot fish makes its run and you see chartreuse line going through your rod guides, the visual cue tells you it’s time to fire up the outboard and chase that fish.

Does C16 offer any other advantages?

Absolutely.

Another way of comparing the various braids is by counting the carriers, or strands; HMWPE solid braids typically have four to 12 carriers. The number of carriers tells you much about a line’s diameter, strength and abrasion resistance. Cortland’s 5-pound-test Master Braid, for example, has four carriers, with a diameter of only 0.004 inches. That’s finer than 1-pound-test nylon monofilament, making for incredible finesse. But you would want to be very careful about using four-carrier braid in a high-abrasion environment. Severing a single strand would cut your strength and abrasion resistance by 25 percent. If a second strand fails, you’re down to 50 percent.

C16 features 16 carriers, so if one strand fails, you still have 15 more. No other fly reel backing can beat that.

HMWPE lines are also notorious for cutting, whether knots or fingers. To be fair, any braided line can cut, and this is especially true with low carrier counts. But the 16 carriers make C16 silky smooth to the touch. The 40-pound C16, which has a diameter of only 0.011 inches, is even softer to the touch than 20-pound Dacron, which feels downright abrasive by comparison.

Is C16 the best choice for every angler?

For run-of-the-mill applications, 20- or 30-pound Micron is all you need, and the price makes Micron very attractive. But when you go for big, powerful trophy fish, you want the best backing you can get.

You want C16.

C16 POUND TEST: 40, 60 and 80.

SPOOL SIZES: 600; 1,500; and 3,500 yards.

C16 COLORS: Chartreuse, blue and white.