Whether it’s a cast net, a landing net or a commercial net, fishing nets in general take a lot of abuse. The thrashing of the fish is compounded by lengthy periods of time spent either in the water or lying wet on a deck or jetty. Moisture eventually damages even supposedly water-resistant and waterproof materials. Because of these factors, owning a fishing net of any kind means inevitably having to fix holes in the netting.
Look closely at the lines around your net for rotted or threadbare sections. Trim these weakened parts of the net away, even if it results in a much larger gap.
Lay the net out on the ground or a table so the hole in the net is flat and exposed. Measure the gaps between lines running across the middle of the hole with a tape measure. Use either the horizontal or the vertical set of lines, but not both. These instructions start with the horizontal cords.
Cut replacement lines for that middle gap with a pair of scissors, making them about 25 percent longer than your measurements. This gives you a little extra line for tying knots.
Tie your replacement lines onto the loose ends of netting with Sheet Bend knots, starting on the left side of the net (also sometimes called a Beckett Bend or Beckett Knot). Lay the two lines alongside each other; make a bend in the loose line from the net and drawing your replacement cord through that bend. Loop the replacement cord completely around the bend before drawing it back under the replacement line and pulling it into a tight knot.
Repeat Step 4 until all the loose ends on the left side of the hole in the net have a replacement line tied onto them with a Sheet Bend knot.
Measure and cut replacement lines for the vertical axis of the gap in the netting, just as you did in Steps 2 and 3, but this time increase the measurement by 50 percent. You will be tying more knots on this set of lines, so they should be longer to compensate.
Tie on the vertical set of replacement cords to the loose ends on the top of the gap in the net using Sheet Bends, just as you did in Steps 4 and 5.
Lay the horizontal and vertical replacement lines across each other, forming a mesh of netting. Working diagonally, down and to the right, tie the vertical lines to the horizontal lines wherever these intersect. Use ordinary Square knots.
Tie the horizontal lines to the loose ends of net line on the right side of the gap with Sheet Bends. Then tie off the vertical lines to the loose ends on the bottom of the gap with the same knot. Cut away the extra leftover line if there is any.