Which force makes a rolling ball stop?

Name the type of the friction in the following figure:

Sita sails a boat with a force of $800 \mathrm{N}$ along an opposite direction of the stream as shown in the figure. If the force applied by the stream is $500 \mathrm{N}$, calculate the resultant force acting downstream (i.e. the direction of river and the boat is the same).

Sita sails a boat with a force of $800 \mathrm{N}$ along an opposite direction of the stream as shown in the figure. If the force applied by the stream is $500 \mathrm{N}$, calculate the resultant force acting upstream (i.e. the direction of the boat is opposite to the direction of the river).