James Malone of Shrewsbury, New Jersey, wants the best connection between fly line and leader:

What is the best way to connect a fly line to the butt section of your leader? I am rather new at saltwater fly fishing, and several people have told me different methods.

Q What is the best way to connect a fly line to the butt section of your leader? I am rather new at saltwater fly fishing, and several people have told me different methods.

The two most popular methods of connecting the fly line to the leader are a nail knot or a whipped loop. Some anglers will use an Albright, but this leaves a stub in the knot that catches in the guides. Others use a loop knot secured with two nail knots - but the line end is usually a stub.

The conventional nail knot can be made with a tube or a needle (called a speedy nail knot). It works pretty well in all lines except the newer clear, monofilament-based lines. These are usually constructed with a nylon core and clear coating (although some are extruded, without a core). If you attach your leader to this line with a nail knot, there's a good chance the pull of a strong fish could strip this coating away from the core.

Still, even with conventional lines, I prefer not to use a nail knot, simply because that method means you have permanently attached the leader to the fly line.
My favorite method - and one I have used since the late 1950s - is the whipped loop. It is made using stout fly-tying thread and a bobbin. See Practical Fly Fishing Knots, Lyons Press, for instructions on constructing this loop. Done correctly, this loop is stronger than the fly line and will last for years of hard use. The advantages of a whipped loop are many. You can change leaders easily. Because the end is rounded, it never catches in the guides. By installing a whipped loop on both ends, you can quickly switch lines on the reel. The whipped loop works in any fly line, including the monofilament types.