Questions from the topic of 'Boats and Streams' are special type of ‘Time & distance’ questions. Questions from ‘Boats and Streams’ have been asked in different competitive examinations.
Questions will be based on still water, down stream and upstream conditions. You will be asked to calculate the speed of boat/current swimmer, time in crossing and distance between two places.
Ensure that you have understood the concept of downstream and upstream and also got expertise in solving questions from different ‘formulae’ and ‘rules’.
If the speed of certain boat in still water is v km/h and the speed of stream is u km/h.,then
Rule  Description 

1  If the speed of a boat/boat/ship in the direction of stream (downstream) is x km/h and in the opposite direction of stream (upstream) is y km/h, then,

2  Let the speed of boat is x km/h and speed ofstream is y km/h. To travel d_{1} km downstream and d_{2} km upstream, the time taken is ‘t’ hours, then time will be \[t=\frac{d_1}{x+y}+\frac{d_2}{xy}\] 
3  Let the speed of stream be y km/h and speed of boat be x km/h. A boat travels equal distance d upstream as well as down stream in ‘t’ hours, then the distance will be \[d=\frac{t\left(x^2y^2\right)}{2x}\] 
4  If a boat takes time t_{1} to travel distance d_{1} downstream and time t_{2} to travel distance d_{2} upstream, then,

5  A boat travels a certain distance d upstream in t_{1} hours, while it takes t_{2} hours to travel same distance downstream, then, \[\frac{Speed \ of \ boat}{Speed \ of \ stream}=\frac{t_1+t_2}{t_1t_2}\] 
6  If a boat takes same time t to travel d_{1} km downstream and d_{2} km upstream, then, \[\frac{Speed \ of \ boat}{Speed \ of \ stream}=\frac{d_1+d_2}{d_1d_2}\] 
7  If a man or a boat covers x km distance in t_{1} hours downstream and covers the same distance in t_{2} hours upstream, then

8  If the speed of a boat in stillwater is a km/hr and river is flowing with a speed of b km/hr, then average speed in going to a certain place and coming back to starting point is given by \[\frac{(a+b)(ab)}{a}\] km/hr 