A boat moves with velocity `vecV_(B)` in still water [Fig(a)]. Velocity measured by observer on ground will be `vecV_(B)` but if water flows at a certain rate it will make the bota move faster or slower depending on whether The boat moves along the steam or opposite to te strem. the velocity measured by an observer on the shore is the vector sum of the velocity of the boat `vecV_(B)` and the current velocity `vecV_(C)`.