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How Specific Gravity Affects Your Casting and Retrieves

by Yoshinori Mitani
How Specific Gravity Affects Your Casting and Retrieves

Choosing the proper fishing line for a specific technique or species can be a daunting task. With several different line types to choose from, understanding whether you should use monofilament, fluorocarbon, or braided line can often times leave anglers scratching their heads. This article breaks down specific differences between nylon, fluorocarbon and braid.

One determining factor in choosing the right line relates to what is known as "Specific Gravity or Relative Density". Specific Gravity or Relative Density refers to the ratio of the density (mass of a unit volume) of a substance to the density of a given measure of the density of a substance in comparison to the density of water. In layman's terms, it simply means the density of a substance, in this case fishing line, in comparison to the density of water.

Keeping this scientific definition in mind we can make a few assumptions about which lines you should choose for a given technique. With the specific gravity of water checking in at 1 gram per cubic centimeter, determining the specific gravity of nylon(often called monofilament in the U.S.), fluorocarbon, and braided lines will allow us to make an educated choice about the proper fishing line to use.

The specific gravity of these lines is as follows.

Nylon: 1.11-1.14

Fluorocarbon: 1.78

Braid: 0.97

Water: 1

These measurements of specific gravity reveal a few important characteristics about each type of line as it relates to the specific gravity of water. Anything with a specific gravity less than 1 will float, so braided line will be the most buoyant, nylon the second most, and fluorocarbon being the densest and the least buoyant of the three-line types.

Those techniques which require your bait to sink, or that you want to keep down in the water column are best served by using fluorocarbon. Techniques such as jigs, deep cranking or jerkbaits can be aided by using fluorocarbon line.

Specific Gravity

Techniques like shallow cranking might be better fitted for nylon if you are trying to keep the bait higher in the water column or trying to get it to float up after deflecting off a piece of cover.

While the floating or sinking properties of a line are a very important product of specific gravity, it can also affect castability. For instance, the sinking nature of fluorocarbon reduces line bow on long casts, and can also aid in better hooksets, as well as increasing sensitivity. This video shows each of the three-line types being cast and compares how it varies between the three types.

So, what does all this scientific jargon mean for you as an angler you might ask? Techniques that require your bait to remain on or near the surface will be best served by using braided line or nylon/monofilament as the specific gravity is the closest to water. The graphic below shows a comparison between nylon and fluorocarbon tied to a topwater.

As you can see the floating properties of nylon can be advantageous when used with a topwater.

See all three lines in the water in this video.

Keeping specific gravity in mind the next time you purchase Sunline will certainly give you a leg up on your competition and allow you to make the proper choice for a given technique. Follow the science of Sunline and catch more fish!