This is a simple and quick way to tie a tripod lashing. The wraps are not woven in and out between the spars. The running end is simply wrapped around all three, snugly but not too tight. In Rope Works Plus, Gerald Findley refers to this lashing as a Tripod Lashing with Plain Turns. Here’s a page right out of the 1967 printing of the BSA Fieldbook:
Notice how the outside legs cross under the middle leg. In that way, the strength of the tripod is not entirely dependent on the strength of the lashing rope, but also on the support given by the wood of the outside legs.
Note: This lashing works very well for most Scout Pioneering applications, but for a heavy tripod, or a large one that will be supporting a lot of weight for a longer period of time, using racking turns (Figure of Eight Tripod Lashing) provides more contact between the rope and the spars.