Most high-end flylines these days come with a loop already formed at the terminal ends of the line. There are people who believe that you should fashion your own loops – if you’re one of those people then you probably already have a favorite method.
For those that either have no experience with the procedure or come across an older line with no welded loops, here is the technique that I use most often. Thanks to the guys at InTheRiffle.com for posting that up for all of us. In a slight but important difference, I'll use Dacron for the wraps, which forms a flatter knot for a more streamlined finish. I dap the Dacron with just a bit of a super glue, and slick over the entire connection with something like Loon's UV Knot Sense or Aleene's Fabric Fusion. Be careful to not over-saturate the connection with the super glue, as it can crack your fly line. Other options include the commonly used and functional nail-knot connection, but I generally avoid this technique in favor of the welded loop.
Capt. Bruce Chard and Deneki Outdoors has put up a video that closely parallels the technique that I use to create whipped loops. 'Slinging' the bobbin around the flyline allows for a quick weld; with practice, you'll be able to fully weld and finish a loop in less than 5 minutes.
Assuming that you have a loop in your flyline, you then need to put a loop in the terminal end of your backing. For various reasons I will discuss later, I use gel-spun braid backing. This can cause concerns when a big fish is putting a lot of pressure on the backing-flyline connection – the braid could literally cut straight through the flyline. To help alleviate this issue, on my big-game reels I use a multi-loop system, as beautifully illustrated here by Cam Sigler.
Based on a Bimini Twist, this knot allows for the pressure from the backing to be spread over a larger surface area on the loop and eliminate the chance that it will cut through your flyline.It's a little tricky, but worth the practice.
Now, once your flyline is wound on and you’re ready to set a leader up, you’re going to have to ask yourself a couple questions. First of all, where are you fishing? So far I have described rigging for my big game equipment, so we’ll assume a suitable location. The jetties, surf, or a boat somewhere nearshore all come to mind. The critters that lurk out there are often big, and often toothy. I don’t mean ‘scrape you up a little’, toothy – I mean slice you to the bone if you’re careless. So that obviously presents a bit of a dilemma in how you construct your leader.
In general, I have more confidence in fluorocarbon leaders. Being extra careful with settling your knots and making sure that everything is secure is more important than with monofilament, but the resulting leader hides from the fish more effectively. For most of my big game applications I rely on fluro, but there are times when mono is more effective especially when fishing small topwaters like gurglers in very shallow water. In skinny conditions, the tendency of mono to float helps keep your fly on top where it belongs.
The opposite can be true too – when sightfishing with crab flies, it can be helpful to have a mono tippet to help keep the line out of the grass.
Jetty leaders I tend to construct in a 50-30-20 progression. This setup works well when targeting species such as Spanish mackerel, ladyfish and redfish. The extra-heavy butt section helps turn over the big flies you may be throwing, especially if fishing topwaters. However, there are situations when I’ll just go with a straight 30lb leader. This is a very useful tactic when I break off a leader on a rock (or fish), and need to quickly get back into fishing, or I am fishing a shooting-head system and need the leader to be thinner diameter so that it sinks well. If tarpon are the target species or if I just think I have a good chance of hooking one incidentally, I will put 10-12” of 50lb fluro on as a bite tippet. This can come in handy for Spanish macks as well – keeps them from slicing through your tippet as easily.
You might be tempted to say, well what the heck, why shouldn't I just go with a straight 50lb leader and cut to the chase!
There is another reason I will go with the 30lb leader – when it comes time to break off a fly which refuses to budge from the clutches of rocks, that 30lb is going to pop before your fly line does. When you’re losing 6-8 flies to the rocks in a day, that makes a big difference.
Bust a leader, save a flyline.