About this lab

Steer a boat across a river with a current. See the resultant velocity, the drift and the crossing time, and find the heading that lands you straight across.

Ideas covered: relative velocity, vector addition, heading.

Common questions

How do you cross a river to land directly opposite?

Aim upstream so the boat’s upstream velocity component cancels the current: sin θ = current speed ÷ boat speed. It is only possible when the boat is faster than the current.