The size the author references in these instructions is ridge-line length. So an 8ft ridgeline is a 10ft hammock. 9ft is 11ft, 10ft is 12ft hammock. The 8ft would be closest to an actual WBBB.
Also, while these instructions are similar in style, most of the dimensions don't match an actual blackbird. I think the author indicates he never saw an actual BB in person before developing this.
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