Diagonal lashing is a type of lashing used to bind spars or poles together, to prevent racking. It is usually applied to cross-bracing where the poles do not initially touch, but may by used on any poles that cross each other at a 45° to 90° angle. Large, semipermanent structures may be built with a combination of square lashing, which is stronger, and diagonal lashing.
Bailing twine has sufficient strength for some lashing applications but rope should be used for joining larger poles and where supporting people sized weights.
Diagonal lashing steps (see image at right);
- Begin with a timber hitch around the juncture of the two poles.
- Make three turns in each direction - tightening steadily as you go.
- Make two frapping turns, tightening the joint as much a possible.
- To end, make two half hitches
- Cinch the half hitches into a clove hitch
A lashing stick can be used to safely tighten the joint. Strength will be improved if the first turn is 90° to the timber hitch and if care is taken to lay the rope turns parallel with no crossings.