Diagonal Lashing

Not every pole joint starts with the two pieces already touching - bracing a frame's diagonal support, for instance, often means starting with a visible gap between poles that a plain square lashing has no way to close, since a square lashing's wraps assume the poles are already in contact. The diagonal lashing solves that specific problem by opening with a timber hitch anchored across the gap, then using the tension of the diagonal wraps themselves to actively pull the poles together before the frapping turns lock everything tight.

The technique alternates diagonal wraps in both directions across the crossing - three turns pulling one way, then three more pulling the opposite way - which is what closes the gap and squares the poles against each other, followed by the same kind of frapping turns a square lashing uses to cinch the whole assembly rigid.

Getting the initial timber hitch anchor genuinely tight and gripping matters more here than in a square lashing, since that anchor is doing real structural work in this lashing - holding against the pull of the first diagonal wraps while they draw the poles together - rather than simply marking a starting point the way it does elsewhere.

Diagonal lashing shows up most often bracing frame corners, X-braces, and diagonal supports in shelter and structure building, anywhere the joint's geometry doesn't offer the poles already touching cleanly at a right angle the way a square lashing assumes - a genuinely common situation in improvised camp or survival construction where poles rarely arrive pre-cut to fit perfectly.

Scouting and pioneering programs typically teach diagonal lashing right alongside square lashing as a pair, precisely because real camp construction projects almost always need both - a raft or bridge frame, for instance, usually has some joints where poles already touch cleanly and others bracing diagonally across a gap, and knowing only one of the two lashings leaves a genuine gap in what a builder can actually construct.

There is a small question of which diagonal to wrap first. Common practice is to start on the opposite diagonal from the timber hitch, though some pioneers deliberately take the first wraps along the same diagonal instead. We have found nothing that settles it, and it reads as a preference rather than a rule.

The diagonal lashing exists for spars that cross without touching, or that spring apart when you try to bring them together. No measured gap defines it - the test is whether the timber hitch can draw the spars into contact when you pull it tight. If the gap is genuinely large, the more reliable fix is trimming or shimming the poles so they meet closer to flush before lashing, since asking the timber hitch and diagonal wraps to close an oversized gap puts far more strain on the anchor than the technique is really designed to handle, and a lashing built that way is measurably more prone to slipping once loaded.