A boat, an island and a helicopter

A boat at \(A\) is 80 km from island \(C\). A helicopter \(H\) hovers 15 km directly above \(C\).

1. Find \(\angle CAH\).
2. At 20:35, the boat sails at 64 km/h towards \(C\). Find its arrival time.
3. At point \(B\), the angle of elevation \(\angle CBH\) is \(68^\circ\). Find distance \(AB\). Give non-exact lengths, areas and other numerical values to 3 significant figures, and angles to 1 decimal place, unless otherwise stated.