VIEW VIDEO: How to Tie a Shear Lashing
DEFINITION: ambiguous |amˈbigyoōəs|adjective(of language) open to more than one interpretation; having a double meaning; unclear or inexact
One Thing is NOT Ambiguous! The shear lashing’s USE is quite clear. References to the lashing in John Thurman’s Pioneering books, in John Sweet’s Scout Pioneering, and the Lashing section in the Pioneering Merit Badge Pamphlets by Pioneering Legend Adolph Peschke all describe its fundamental use exactly the same way. Putting it neat like John Sweet: Use a sheer lashing “when two spars are to be opened out like scissors to make a pair of sheerlegs,” or right to the point like John Thurman in Pioneering Projects, the sheer lashing is “used for lashing together two parallel spars which will be opened out of the parallel to form sheer legs.”
What are sheer legs? Simply put: sheer legs are two upright spars lashed together at the tips with the butt ends splayed apart to support some kind of weight. Most always, in Scout Pioneering we use sheer legs to form an A-Frame.
Ambiguous? Yes. Let’s start with ambiguous spelling! Most modern references to the lashing spell it s-h-e-a-r. Yet, the much respected and revered John Thurman was emphatic that the correct spelling was s-h-e-e-r!
Terminology. In John Sweet’s book, sheer lashing has two different forms each with the same name. When two spars are lashed together for strength, or lap-jointed to extend their length a sheer lashing is used BUT with the clove hitches tied around both spars and without any frapping turns. He still calls it a sheer lashing, but of course this is commonly known as a round lashing! John Thurman refers to a true round lashing as the Sheer Lashing Mark II and the lashing used to make sheer legs as the Sheer Lashing Mark I.
Let’s take this opportunity to further clarify two lashing designations that keep popping up. A SHEAR Lashing is used to make shear legs. A ROUND Lashing is used to attach one pole to another in the same direction as in extending the overall length of shorter poles. (It can also be used to bind more than one pole together to make a stronger pole.) SHEAR Lashings incorporate frapping turns. ROUND Lashings do not! Along these lines, the West Country Shear Lashing should be called the West Country Round Lashing, and rightfully so!
Nowhere is this stated more clearly than in Gerald Finley’s book, Rope Works: “West Country Round Lashing is also called West Country Shear Lashing, but this name contributes to the confusion caused by lumping shear and round lashings together. West Country Round Lashing is used to form a rigid joint between two parallel poles; it does not form the flexible joint of a shear lashing and it has no frapping turns.”
Two-Spar Shear Lashing. To add to the possible confusion, Adolph Peschke calls what John Thurman refers to as the Sheer Lashing Mark I (which is in actuality THE shear lashing) the Two-Spar Shear Lashing. This name can also be related to the tying of a Tripod Lashing With Plain Turns, wherein the procedure is exactly like the Two-Spar Shear Lashing but with three spars. It follows that it’s easy to dub this tried and true form of tripod lashing (just like the Two-Spar Shear Lashing) the THREE-Spar Shear Lashing. The Two-Spar Shear Lashing is used to make an A-Frame, and the Three- Spar Shear Lashing is used to make a simple tripod.
Ambiguity in Tying the Lashing. Though the formation is the same: clove hitch around one spar, six to eight wraps, two fraps, finish with clove hitch around one spar, there are varied approaches to actually tying the shear lashing. These discrepancies all hinge on… the hinge. (Pun intended.) The spars have to pivot in order to spread out the desired distance. How can this be accomplished so the lashing is tight but not so tight that when spreading the legs into position, the legs and lashing rope resist the strain to the point that something breaks? The tighter the wraps, and the more wrapping turns you take, the stiffer the lashing will be.
- One view is to make the wraps and fraps on the loose side, concluding they’ll tighten when the legs are spread.
- Another view is to place a small block of wood between the spars to yield adequate room for the frapping turns.
- Another view is to make the wraps moderately tight and then before frapping, spread the legs a bit to allow room for the frapping turns, being careful not to close the spars on the lasher’s fingers!
- Finally, another view is to complete the wraps, then spread the legs to the desired width, and then take tight frapping turns.
Whatever works well will also depend on the diameter of the spars, how straight they are, and indeed on the structure itself.
SCOUT PIONEERING 
After messing around with the figure of eight approach as depicted in the 2008 printing of the Pioneering Merit Badge Pamphlet, I conclude this is most conceivably the result of another innocent error in interpretation on the part of the illustrator, author, or both. Applying the wraps in that manner yields a rickety result at the top of the shear legs because after frapping there’s just too much of a gap to make the structure tight. In other words, in my book, this figure of eight method just ain’t no good when ya only got two poles.
Personally, for an A-frame, I don’t really like a Diagonal Lashing up there either. It might be okay, but seems to provide a looser joint. At this point, I’ll stick with a nice shear lashing, and if we want it really tight, a Square Lashing tied at 90º and then squeezed into position for lashing on the bottom ledger appears to eliminate any possibility of racking. HOWEVER, don’t make the Square TOO tight! We don’t want that excellent creaking sound to change suddenly into a crunch or a loud snap because too much strain is applied when forcing the legs into position!