Willis Knot (Leadcore Line)

Some novice Great Lakes trollers don’t know what leadcore line is, or have never used it! Well, it is simply a braided nylon line that has lead in the center.  It’s most commonly available in#18, #27, #36 pound tests,  however you can get it in many other strengths as well, like: 12, 15, 20, 25, 40, 45, 50, 60 and 63  pound tests.  The weight of the line does not seem to affect the sinking rate,  but it is wise to use one weight class and stick with it to reduce confusion.  The line changes color in ten yard increments to be able to see exactly how much line you have out. A full spool of 100 yards long core is commonly called a “full core”. So, a core and a half  is 15 colors or 150 yards and a half core is 5 colors or 50 yards.  The real sinking rate depends entirely on the size, weight and type of the lure being trolled. Trolling speed is also a determining  factor! A normal speed will bring the lure down from 4-6 feet on average. A full core should bring a lure down about 50-60  feet in most cases. This is a  recommended knot to connect core to both backing and the leader:

Make a loop in the leadcore, about 4 inches from the tag end.

willis 1

Next step is to slide back the outer coating (Sheath) on the leadcore line, approximately 3 inches.
Cut the lead off, then slide the out coating (Sheath) back out until it’s snug.


Ensure that the end of the monfilament you are going to insert into the dacron sheathing is cut at a slight angle or flat. You don’t want it “Flattened” like when you bite it off ;} .
Insert your monofilament leader, so that it butts up with the lead inside, then work the knot down towards the tag end (Keep the monofilament butted up against the lead inside as you work the knot down).
 willis 3

Pull the knot tight, holding the dacron on each side of the knot, then snug it up tightly, holding the monfilament/leadcore to really cinch it down.
willis 4.

The knot works by using the friction between the line from the leader and the Nylon/Dacron sheath from the Leadcore. The tighter the knot gets the more friction is added. The only weak spot is where the lead and the leader meet in the sheath. You add more knots…you add more friction…the less likely the leader line will pull out of the sheath. I tested that by using the Willis to attach the Leadcore to Fireline backing and one knot would not hold…but I added a second knot and it held. Now I add three knots if I tie to Slippery braids and two knots to mono lines and I have never had a failure. If you really want to secure the knot, some people use a drop of superglue or elmer’s glue on the knot and let it dry.

1) Leadcore most commonly comes in 18#, 27#, and 45# test, but #45 test is not heavier weight-wise than #18 test. The difference in weight sizes is the strength of the dacron sheathing por of the line and it’s relative strength.
2) All three weights of Leadcore (#18, #27, and #45) have the same depth scale. ~Roughly 4′-6′ per color.
3) Several manufacturers of leadcore line suggest that after 25 feet of depth, thermocline affects the sink rate (The water density increases). They suggest 3 colors is ~15′ down, 5 colors ~25′, 8 colors 30′, and 9 colors 35′.