For most frequently asked questions, by far we receive the most regarding knots. In this article we are going to focus strictly on trolling fly, swivel and leader connections highlighting differences in line material.
To get the basics out of the way, it is important to understand subtle differences between fishing line (standard mono), fluorocarbon line (mono with a fluorocarbon coating) and fluorocarbon leader (100% fluorocarbon material).
Standard monofilament lines are the least expensive of the bunch, and the most forgiving. Mono's have the best overall internal knot strength, but...mono's absorb water, break down in UV light and stretch. And....standard mono has very poor abrasion resistance and poor clarity. Once fully extended, saturated, chafed and chalky looking from UV breakdown...you are living on the edge from a strength perspective. Tying knots with standard mono is pretty basic, with just about any knot of preference working well. Little to no friction is built up, and generally knot strength in mono is close to the breaking strength of the line itself (rated on the packaging).
We are going to skip analyses of fluorocarbon coated mono for purposes of this article, other than to say knot tying is very similar to that of straight mono. Lots of forgiveness, medium heat friction build up, similar stretch and generally a good barrier to UV and water absorption. Knot strength is again close to rated breaking strength. Medium abrasion resistance, medium clarity.
Fluorocarbon leader material, in particular true leader material such as what we use for trolling fly leaders, diver leaders and copper leaders are a different animal. Different manufacturers utilize different fluorocarbon resins to attribute different characteristics in their leader materials. Some add stretch, some add abrasion resistance, some use lower quality resins just to offer a lower priced product. In each situation, it is important to know what you are dealing with from a material perspective before you run off and start tying knots. Tie the wrong knot in the wrong material and you are asking for potential trouble when you least need it. Superior abrasion resistance, zero water absorption, excellent clarity, medium to poor knot strength.
The knock amongst all fluorocarbon leader material is lower knot strength compared to mono. On average, most fluorocarbon leader material using standard knots fall somewhere in the 60-70% range of rated breaking strength. This means your 20lb fluorocarbon leader material is 30-40% weaker than 20lbs..inside the knot. Blood Run Fluorocarbon Leader material, by virtue of the resins used, land in the 70-80% of rated breaking strength category. No other manufacturer is higher than 80% strength inside the knot. That is just a limitation of the material in general.
The advantages of the material itself far outweigh the disadvantage of weak knot strength...as long as you are tying the right knot. You generally cannot just run off and tie any old knot, or your favorite mono knot, with fluorocarbon leader material and expect the same results.
Generally speaking, Blood Run Fluorocarbon Leader Material is on the stiffer and harder end of the equation, using higher quality resins to stand up to its specific intent for which it was designed. There is no doubt that the "whip" factor of trolling flies and meat rigs significantly adds to the attraction of those presentations, and a stiffer leader material is the perfect leader for this application. Because of the "hard" feel to the line, which results in outstanding abrasion resistance, careful consideration must be taken when tying knots to ensure the highest knot strength that you can get.
Remember, a hard fluorocarbon leader material when cinched down, will create friction. Friction weakens the leader, and will cause eventual failure. Over 90% of fluorocarbon leader failures occur within the knot. It is very important to "slightly" lube the material as you cinch down your knots. Over lubing will cause the knot to "slip" when put under stress...leaving you with the proverbial "pigtail" in your hand after you lose your last fish in a tournament. Under lubing your knot will create too much heat and friction which will cause the knot to fail sooner than expected.
The knot you decide to use also plays a large role in the ultimate strength of the leader. Different knots are used in different applications, and for the majority of us fishing salmon, we are looking at leader in the 20lb to 50lb test range. Realistically, anything larger would require a crimp rather than a knot.
As testing has concluded, probably the most durable knot when considering high knot strength ( not rated line breaking strength on the packaging) would be the San Diego Jam Knot. It is a knot rarely mentioned, but used frequently in saltwater. Closely examining the construction of the knot, we can see that it is a "low friction" knot which would respond well to lubrication while still allowing for a tight cinch. We have not spent alot of time using this knot in our application for salmon, mostly because we feel we have an equally strong and simple knot that works in all situations.
There is also another knot, very similar to the knot we recommend below, called the Miller Knot. It is a highly rated strength knot for fluorocarbon leader material. It is a compression knot which by it's design reduces friction and maintains higher breaking strength inside the knot.
Our favorite fluorocarbon knot is the modified clinch knot. Again, using a series of "wraps" and a tag end running through a loop, it responds well to lubrication and allows for a higher rated knot strength compared to other favored knots such as Palomars, etc.
In addition, there is a unique feature to this knot that most are unaware of, but plays a HUGE role in fishing with trolling flies, and that is the double loop. The double loop on the eye of the hook, allows the hook to "hang straight" in most trolling situations, and is less likely to become cocked off to one side or another by side swipes from a fish. Why is that important? Try and catch a fish on a trolling fly with your hook offset and see how many fish you will catch....zero! If the hook does become offset after landing a fish, it is a simple swing back to center and you are back in business with a straight hanging hook. Single loop knots, like the San Diego jam, will allow the hook to wander inside of the loop and slip rather easily and become offset. This is the same for all other knots with a single loop through the eye of the hook.
What does this mean? When you keep getting knock offs on your flies, it means fish are swiping at it and not getting the hooks jammed into their jaws because the hook is offset. Or, it means you are just flat out not getting bit because the action of your fly is wrong because of the offset hook. One more time..your hooks MUST hang straight on trolling flies and meat rigs in order to have the proper action, and best hook setting performance. Period.