I found the chart on page 14 interesting. Wigley is an apt name. The wiggle in the line that is Best Fit, suggests to that accurate slow speed hull testing may not be so much difficult and difficult to understand. Might there be something in that squiggle?

It's interesting that the review of the literature reveals that the formulas used in hull design are largely empirical.
Then they do their 'research' using a computer program based on the best available theories.

I don't know enough to dispute their results, but if their formulas are based on empirical results it seems reasonable that further physical testing would yield better results -- or discover something new.

With CNG being so widely available it's feasible to test a variety of hulls, radical ideas, lengths.
We've never even come close to the Fish solution. Propulsion being integrated with hull length.