knot used to join two lines.
zeppelin bend (Wikipedia)
A zeppelin bend (also known as the Rosendahl Bend) is an end-to-end joining knot formed by two symmetrically interlinked overhand knots. It is stable, secure, and highly resistant to jamming. It is also resistant to the effects of slack shaking and cyclic loading.
Front view
Back view
Loosening / untying
| Zeppelin bend | |
|---|---|
 | |
| Names | Zeppelin bend, Rosendahl bend, Rosendahl's knot |
| Category | Bend |
| Related | Zeppelin loop, Hunter's bend, Ashley's bend, Alpine butterfly bend |
| Releasing | Non-jamming |
| Typical use | Joining two ropes of similar size |
| Instructions | [1] |