Note: I just repeated the speed experiment and got pretty much 0 error, my bearing wasn't on 11.3° so maybe this isnt such an issue as I thought
I was going to repeat because using % as an error before non-linear equations isn't really fair.
https://ibb.co/9vtJRm6
I also did a quick test in the tutorial
Speed measured using map = 6.08 knots
Speed calculation with 1 boat length = 6.17 knots, error 0.09
Speed calculation with 2 boat lengths and rounding = 6.014 knots, error 0.066
Maybe no significant gains here either!