Heavy monofilament and fluorocarbon leaders used for marlin and big tuna are too thick to tie reliable knots. Instead, offshore anglers use crimps: small metal sleeves compressed around the leader to form loops for hooks, swivels, and lures. A good crimp is very strong. A bad one slips at the worst possible moment.
What you need
- Crimp sleeves sized for your leader diameter. Manufacturers list which sleeve matches which leader pound test.
- A quality crimping tool with dies matched to your sleeves.
- Chafe gear such as clear tubing or a spring to protect the loop.
- Leader material and a sharp cutter.
Match the sleeve to the leader
This is the most important step. A sleeve that is too big will not grip; one that is too small cannot fit two passes of leader. Always use the sleeve size recommended for your leader's diameter, and the matching die on your tool.
Step by step
- Slide the sleeve onto the leader.
- Add chafe tubing if using it, then pass the leader through the hook eye or swivel.
- Bring the tag end back through the sleeve to form a loop, leaving a short tag.
- Position the sleeve so the loop is the size you want and the chafe gear covers the contact point.
- Crimp the sleeve with the correct die. Many anglers crimp double sleeves in two spots, not right at the ends, to avoid cutting the leader.
- Trim the tag and lightly smooth any sharp edge.
Test every crimp
Pull hard on every crimped connection before you fish it. Some crews use a scale to load-test. If it slips at all, cut it off and redo it.
Common mistakes
- Using the wrong sleeve or die size
- Crimping too close to the sleeve end, which can nick the leader
- Over-crimping and crushing the leader
- Skipping chafe gear on big-game rigs
Inspect regularly
Check crimps after each fish for cracks, sliding, or corrosion. Replace any that look questionable. See when to replace trolling leaders.
For loop protection, read our guide to chafe gear and springs, or skip the work with pre-rigged trolling lures.
