A cast net closes by pulling a single rope, called a handline or lanyard, that draws the weighted bottom edge of the net together like a purse. When you throw the net, it spreads into a flat circle and sinks. When you pull the rope, the bottom cinches shut, trapping everything inside. The exact way this happens depends on the net’s design, but the core principle is the same: gravity opens it, and you close it.
What Happens When the Net Hits the Water
A cast net is a circular piece of mesh attached at its center to a long handline. The outer edge is lined with lead weights spaced at regular intervals. When you throw the net, it fans out into a wide disc and lands flat on the water’s surface. The lead weights immediately start pulling the edges straight down, and the net sinks over whatever fish are below.
The speed at which the net sinks matters. Heavier weights close the trap faster, giving fish less time to dart out from under the falling edge. A well-weighted net carries between 1 and 1.5 pounds of lead per foot of net radius, so a 6-foot net weighs roughly 6 to 9 pounds total. Deeper water calls for heavier weights because the net has farther to sink and fish have more time to react. Mesh size also plays a role: smaller mesh creates more water resistance, which slows the sink slightly but prevents small baitfish from slipping through.
How Pulling the Line Closes the Net
The handline runs from your wrist, through the center of the net (called the horn), and connects to a series of smaller lines called brails or lead lines that fan out to the weighted bottom edge. Think of it like an upside-down umbrella: the brail lines are the ribs, and the handline is the handle.
When you pull the handline upward, those brail lines pull the weighted perimeter inward and upward toward the center. The bottom of the net gathers together, sealing off any escape route. The net transforms from an open disc into a closed bag with the fish trapped inside. You then continue hauling the net up hand over hand until you can grab it and dump the catch.
Drawstring vs. Pocket Designs
Not all cast nets close the same way. The two main designs handle the bottom closure differently.
A drawstring cast net works exactly as described above. When you pull the handline, the entire bottom edge draws together into one large pouch beneath the fish. This design is simple and effective, especially for larger baitfish that can’t slip through the gathered mesh.
A pocket cast net takes a different approach. Instead of relying entirely on the drawstring action, it has small built-in pockets sewn along the bottom edge where the lead weights hang. These pockets are created by extra folds of mesh that form little traps around the perimeter. As the net sinks and then gets pulled upward, fish that try to escape along the bottom edge swim directly into these pockets and get stuck. Even if the main body of the net doesn’t cinch perfectly, the pockets act as backup traps. This design is popular for catching smaller, faster baitfish that might otherwise find gaps in a drawstring net.
Why a Cast Net Sometimes Fails to Close
The closing mechanism is straightforward, but several things can go wrong. The most common problem is a tangled brail line. If one or more of the lines running from the handline to the lead edge get twisted or knotted, that section of the net won’t pull inward evenly. The result is a gap along the bottom where fish escape. Kinks in the lines cause the same issue on a smaller scale, preventing the net from gathering smoothly.
Uneven weight distribution is another culprit. If lead weights break off or shift position, part of the net sinks slower than the rest. This creates a lopsided closure where one side seals while the other stays open. Regularly checking that all weights are intact and evenly spaced prevents this.
A poor throw also undermines the closing action. If the net doesn’t open into a full circle when it hits the water, it covers less area and may land with folds or bunches in the mesh. Those folds can prevent the brail lines from pulling the edge together cleanly. The net needs to land flat and round for the geometry of the closure to work as designed.
The Role of Weight and Mesh Size
How quickly and completely a cast net closes is largely a function of its lead weight and mesh size working together. Heavier weights per foot mean the perimeter sinks faster, reducing the window fish have to escape before you start pulling. But heavier nets are also harder to throw, so there’s a practical limit.
Mesh size determines what stays inside once the net closes. A quarter-inch mesh traps tiny baitfish that would swim right through a one-inch mesh. But smaller mesh also creates more drag in the water, which slows both the sink and the retrieval. For most inshore baitfish applications, a mesh between a quarter inch and three-eighths of an inch balances catch retention with sink speed. Larger mesh works better for bigger targets in deeper water where you need the net to drop fast.