[wmoser]

Ok, I glanced at the article and as another engineer, yes it looks sketchy and probably isn’t safe (applying the rule from rigging of: if something doesn’t look right it probably isn’t). I felt the need to address the other issues you brought up about being impossible to calculate because it’s wood. Wood is the original composite material and has been used to safety build bridges, buildings, ships etc. For the most part your calculations won’t be as exact as with metal or other engineered material but there has been lots of research into this. The US Department of Agriculture/ US Forest Service even publish a free book about it. [1] The lumber looks like it was bought from a home center and so likely has minimum strength expectations [6-3 of afore mentioned book].

I just felt the need to dispel this rumor that is quite dangerous that I see all the time at work where people use 1/4 wire rope slings with unrated hardware as part of rigging instead of 1/2 inch Manila rope because “That rope doesn’t have any rating, it’s natural”. (It does, about 1/2 the wire rope, but needs knots or splices to attach it to thing being lifted, not the unrated hardware that comes with the wire-rope.) Like someone posting further down, I’m more immediately concerned that there is no brace to prevent racking or the use of ratchet straps as a lifting device.

[1] https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr11...