One might try to set the tilt adjustment of the motor as far forward/down as possible. This would tend to drive the bow downwards. Most motors are designed to adjust the tilt stop outwards, so the thrust of the prop pushes the bow up. This is desirable in getting a planing hull up over the bow wave so that it can plane. Highly undesirable on a displacement hull, forcing the stern to squat. Also, note that the transoms of small planing hulls where these small outboards are typically mounted are often angled aft slightly. Now you can understand why the tilt angle favors tilting the prop up and out.
With a displacement hull, once you hit theoretical hull speed, mostly dependent on waterline length, as you add more power, you can't increase the wavelength between the bow and stern wave anymore (It's fixed by the waterline length.) All additional power applied to the boat will increase speed slightly, as TSBB 2 notes, but will also serve just to increase the AMPLITUDE of the waves. Energy gotta go somewhere, and it can't go faster, because the speed of a wave is dependent on it's wavelength. Longer wave=faster. Longer waterline=faster. (Except for planing hulls.) Your theoretical hull speed is only 5.84 knots.
http://www.sailingcourse.com/keelboat/cal__hull_speed.htm Exceeding that serves mainly to make the bow and stern wave taller (amplitude.) I remember as a kid reading my Grandfather's Chapman's that exceeding hull speed too much can increase the wave amplitude enough that the mid section of a ship is not sufficiently supported, and could break the ship!
