Independent guide: Swaging is done with specialist machinery. The information here is for understanding and inspection, not DIY swaging of structural rigging.
Quick answer
Swaging permanently presses a stainless terminal onto the end of a wire. A machine squeezes the terminal barrel until it grips the wire strands. It is the most common way to terminate standing rigging and lifelines on production yachts because it is quick, compact and strong when done correctly. Swages are inspected for cracks along the barrel, bending, rust weeping and broken strands at the neck.
How swaging works
- Rotary swaging hammers the barrel between rotating dies in many small blows, producing a smooth, round, slightly lengthened barrel.
- Hydraulic or roll swaging squeezes the barrel in a press or between rollers. Results depend heavily on the machine, the dies and the operator's process.
Either way, the terminal must match the wire diameter and construction, and the finished diameter should be checked with a gauge.
Common terminal types
- stud (threaded) terminals for turnbuckles
- fork (jaw) terminals
- eye terminals
- T-ball terminals for mast tangs
- stemball terminals for masthead and spreader fittings
What a good swage looks like
- straight, not banana-shaped
- smooth barrel without seams or flats
- finished diameter within tolerance
- wire entering squarely, with no birdcaging or kinks at the neck
Where swages fail
| Problem | Usual cause |
|---|---|
| Longitudinal crack in the barrel | Stress-corrosion cracking, over-swaging, fatigue |
| Rust weeping from the neck | Water trapped inside, crevice corrosion of the wire |
| Broken strands at the neck | Fatigue, poor articulation, a missing toggle |
| Bent swage | Side loading, the stay not free to align with the load |
A single crack is enough to condemn the stay. See how to tell if rigging needs replacing.
Swaged or mechanical?
| Swaged | Mechanical | |
|---|---|---|
| Fitted | In a workshop with a machine | With hand tools, anywhere |
| Re-usable | No | Yes, with new cone or wedge |
| Internal inspection | No | Yes, can be disassembled |
| Cost per terminal | Lower | Higher |
| Typical user | Production and coastal boats | Bluewater and remote cruisers |
See how to decide: swaged or mechanical.
By boat type
- Lifelines: most are swaged; failures at the swage are common on older sets.
- Trailer sailers: stays bent repeatedly during mast raising; lower swages need frequent checks.
- Bluewater yachts: carry spare mechanical terminals and wire for emergency repairs.
- Tropical boats: heat and humidity accelerate crevice corrosion inside swages.
Frequently asked questions
What does a cracked swage look like?
A cracked swage usually shows as a fine hairline running lengthways along the barrel of the terminal, often starting at the neck where the wire enters. Rust weeping from the neck, a banana-shaped bend in the swage, or broken wire strands at the entry point are also warning signs. Any of these means the stay should be replaced.
Can a swaged terminal be re-used?
No. A swage is permanently pressed onto the wire. When a stay is replaced the swage is cut off with it. Mechanical terminals such as Sta-Lok or Hi-Mod can be re-used with new internal parts.
Are swaged terminals safe for offshore sailing?
Properly made swaged terminals are used on a very large number of offshore yachts. Some bluewater sailors prefer mechanical terminals because they can be inspected internally and assembled at sea with hand tools, which simplifies a repair far from a rigging shop.