We get lead line data from the 1920's.
We send the data to a factory in italy.
A worker on minimum wage who has probably never seen a boat transposes said data into a puter.
We pay 300 quid+ for the data so don't like to consider its provenance.
We then load it into a chart plotter that lets us see the whole thing in 3D.
Look I can SEE the boat fits between those rocks.........