In the past rigs were made with dropper knots. While this was an effective way of attaching a hooklength to a rig body it meant that a number of different knots had to be used in the construction of the rig, and there was limited ability for the rig to adapt to twists and tangles caused by tides and baits rolling around the seabed.
Using a modern trapped swivel method creates a stronger rig, which is much less likely to tangle or end up with twisted, weakened line. As the diagram above shows the trapped swivel gets its name as the swivel is trapped between two beads using crimps, but power gum could also be used. This creates the point where the hooklength is attached to the main rig body. This is better than using the dropper knot for the following reasons:
- Less knots are used. The dropper knot weakens the whole rig and is a fairly complicated and bulky knot.
- The tide can cause rigs to move around in the tide. Because a trapped swivel can rotate through 360 degrees it can always flow with the tide and not tangle in any way.
- The incorporation of the swivel means that the baited hook can roll around the seabed and twists will be eliminated before reaching the rig body. Obviously a rig made with dropper knots has no way of eliminating this twist. Reeling in a fish can also cause line to twist (especially species such as conger eel), another reason to use trapped swivel rigs.
Making trapped swivel rigs is easy enough. The crimps, beads and swivel are threaded onto the line in the correct order (see diagram above). The components should not be bunched up too tight as the swivel needs to be able to spin around. Once the components are in place the crimps should be gently but firmly pressed in place with specialist crimping pliers. There is still a place for dropper knots in sea fishing – anglers fishing rock marks who are likely to lose a great deal of rigs still use old-style dropper knots to save money on rig components, but in the vast majority of angling situations the trapped swivel method is used due to the advantages this method provides.