There are two ways to fish for crab. One way is to use a baited, wire cage called a crab pot. The crab is just smart enough to enter the cage, but not smart enough to get out. The other method uses a trot line, which is a section of rope on the sea floor. Bait (often chicken necks) is tied to the rope with strings called "snoods" every foot or so. Crabs grab the bait and refuse to let go, so when the trot line is pulled up the crabs come with it. After they break the surface the crabs usually fall into a hand-held net.
Cut a roll of parachute cord into 8-inch lengths with scissors. Use the parachute cord sections for snoods. Tie the parachute cord snoods to a 100-foot length of 5/32-inch polyester rope. Tie the snoods with any knot you know, so the snoots are arranged every one to two feet along the whole length of the rope.
Tie a 3-foot long piece of one-inch link, galvanised steel chain to each end of the 5/32-inch polyester rope.
Tie a 25 foot long piece of 3/8-inch nylon rope to the untied end of each chain using any knot. Nylon is more elastic than polyester and more likely to float. Tie a buoy or float to the unchained end of each 25 foot long piece of 3/8-inch nylon rope.
Tie a second 25 foot long section of 3/8-inch nylon rope to each buoy. Tie a concrete block to the opposite end of each of these ropes.
Tie chicken necks or other bait to all the snoots. Lay, or "trot," the line from a slow moving boat.
Throw one breeze block into the water as the boat moves and let the line play out. Throw the other breeze block in the water when the line is fully extended. Locate the line using the buoys.
Trot the line parallel to the shore.