Boat and Stream Concept — Formula, Tricks and Solved Examples

Q1. What is boat and stream concept?

Boat and stream problems involve a boat moving in a river where the water is flowing. The speed of the boat is affected by the direction of water current. When the boat moves in the same direction as water it is called downstream and when it moves against the water it is called upstream. This topic is based on relative speed concept from time speed and distance and is asked in CAT, SSC CGL, Bank PO and Railway exams.

Q2. What is downstream speed formula?

When a boat moves in the same direction as the water current it is called downstream. In downstream the water current helps the boat so downstream speed = Speed of Boat plus Speed of Water = B + W. Downstream speed is always greater than the speed of boat in still water.

Q3. What is upstream speed formula?

When a boat moves against the direction of water current it is called upstream. In upstream the water current opposes the boat so upstream speed = Speed of Boat minus Speed of Water = B minus W. Upstream speed is always less than the speed of boat in still water.

Q4. How to find speed of boat in still water?

Speed of boat in still water = (Downstream speed + Upstream speed) divided by 2. If downstream speed is D and upstream speed is U then B = (D + U) / 2. This formula is derived from the downstream and upstream formulas and is one of the most important formulas in boat and stream problems asked in competitive exams.

Q5. How to find speed of stream?

Speed of stream = (Downstream speed minus Upstream speed) divided by 2. If downstream speed is D and upstream speed is U then W = (D minus U) / 2. This formula directly gives the speed of water current. Speed of stream is always less than speed of boat in still water otherwise the boat cannot move upstream.

Q6. What is the relative speed when two boats move towards each other?

When two boats move towards each other in a river the speed of water cancels out and has no contribution to relative speed. Relative speed of two boats moving towards each other = B1 + B2 where B1 and B2 are their individual speeds in still water. Similarly when two boats move in the same direction relative speed = B1 minus B2.

Q7. Which competitive exams cover boat and stream questions?

Boat and stream is asked in almost every competitive exam including CAT, SSC CGL, SSC CHSL, Bank PO, Bank Clerk, Railway RRB, CSAT and all state level competitive exams. It is closely related to Time Speed and Distance so mastering both topics together is highly recommended.

Q8. Where can I practice boat and stream questions?

After understanding the concept you can practice on our Boat and Stream Exercise page which contains a large number of solved practice questions covering all types of problems asked in competitive exams. You can also check our Time Speed and Distance Concept page for related topics.