The incident likely has little to do with the length/beam/displacement of the lifted vessel and more to do with the straps selected, how they were used, and perhaps whether either set of straps could cope if burdened with a major part of the load. Passing of time means the finer details escape me now, but my involvement with a case of a failed strap during the lift of a substantial steel sailboat revealed the ways the straps must be used, especially how the ends are attached(the method chosen can greatly affect SWL), the need for vigilant strap inspections,the need to return straps to the manufacturer for any repair, and of course the use of straps adequate to the lift. Straps are in constant daily use on wheeled travel-lifts worldwide, they are an adequate system if used properly.
I am very sorry for the owner of the dropped vessel and hope it turns out as well as possible.
