This is the boss. No calculator, and every value is pinned so it fits in your head. One ferry, one river, and every answer feeds the next: the speed over the ground, then the heading of the track, then the crossing time, then the drift — and finally the verdict the pilot actually cares about, which is where the boat touches the far bank. Write each line down as you go; one early slip floats all the way downstream.

Two things worth carrying in: every track here is a 3-4-5 triangle in disguise, so its length is Pythagoras done in your head. And that triangle's own angles are $36.9^\circ$ and $53.1^\circ$ — the pair every Grade 12 student should recognise on sight, the way you recognise $\sqrt{2} \approx 1.414$. One of them will be waiting for you. Nothing else in here needs a keypad.

Everything from the chapter rides along. 5★ under par is the chapter crown. Cast off.