Aboat weighing 9.0 × 102 newtons requires a horizontal force of 6.0 × 102 newtons to move it across the water at 1.5 × 101 meters per second. the boat’s engine must provide energy at the rate of

-- The boat's engine is providing 600 newtons of force.

-- Every second, the force pushes on the boat for 15 meters.

-- So during that second, the engine does (15 x 600) = 9,000 J of work.

-- The rate at which the engine provides energy to move the boat is

                 9,000 joules per second  =  9,000 watts.

-- (The energy comes from chemical energy
stored in the gas that the engine burns.)

This is kenetic energy.